Amber Book - PDD

Question 1

Why would you fill a hollow CMU?

Answer 1

Grout: easy-flowing cementitious material poured into a CMU wall from the cavity openings in the top every four feet as the wall goes up. Used for compressive strength, horizontal rebar and vertical rebar added for tensile strength. Used for load-bearing walls (including those that resist seismic). See here to learn more.

Hollow: CMU cells with air are better insulators than grout-filled, but obviously weaker than grout-filled reinforced block.

Vermiculite-filled: loose granular mineral stuff poured into the cavities for increased thermal resistance, increased sound transmission loss, and improved fire rating (performs better than air in all three). In older construction, vermiculite may contain asbestos.

Perlite- filled: loose granular stuff poured into the cavities; looks like small packing peanuts, if small packing peanuts were made from stone. The process for making perlite: volcanic glass is mined, then heated until it pops like popcorn, so it has tiny air pockets each of which is a good insulator. Used for increased thermal resistance (slightly better than vermiculite and meaningfully better than air).

Polystyrene bead insulation: Styrofoam beads poured into the top of a CMU wall. Used as insulation.

Injection-foam-filled: increased thermal resistance (insulation). Can be injected from either the inside or the outside and doesn’t need to be poured in from the top so it can be used in renovations where the top of the wall is not accessible. Vermiculite, perlite, and polystyrene beads pour out of the wall like sand if you need to cut into the blocks for any reason after they’ve been filled. Injection-foam-filled CMU doesn’t have this problem. Plus with vermiculite, perlite and polystyrene beads, you don’t really know if the granules have made it down to all the cavities below (what if there was a clump or obstruction and some of the cells went unfilled?). Here, foam is injected into multiple holes in the wall, so you know each cavity is filled. These closed-cell foams also serve as an air barrier.

Question 2

Duct and pipe bracing detailing

Answer 2

To prevent sway in an earthquake

Question 3

Materials with high embodied energy

Manufactured with high heat:

Ceramics

Glass

Stainless or galvanized steel

Concrete (but, because of its weight, can look on tables like it has low embodied energy when measured on a per-kilogram basis)

Manufactured with intense chemical processes and petrochemical use:

Epoxies/Resins/Formaldehyde/many adhesives

Paints and stains

Foam insulation (polystyrene, spray-foams, polyisocyanurate)

Plastics/Vinyl/PVC/melamine/polycarbonate

Engineered wood products (MDF, Glue-lam)

Manufactured with intense mining processes:

Copper

Aluminum

Stone

Answer 3

Materials with low embodied energy

Cellulose and glass fiber insulation

Wood (depends on what powers the kiln and whether you include the loss of the carbon-removal capabilities of the tree that was cut down)

Gypsum board and plaster

Rammed earth

*note that a given manufacturer can easily greenwash here by measuring embodied energy per weight (concrete looks better because it is heavy), per square foot (vinyl looks better because it is thin), or per volume (foam insulations look better because they’re big). The most legit data I’ve found is from the University of Bath and can be accessed at https://drive.google.com/file/d/1_R9HEBppxEy5tJOUN3nFCSstM2p9NR8c/view.

Question 4

What type of rubber should your gasket be made of?

Answer 4

Natural Rubber: Strong but breaks down quickly in sunlight

Styrene-Butadiene rubber (SBR): less expensive but not as strong nor resilient over prolonged pressure

EPDM: most water resistant (also used as roofing membranes), resistant to abrasions and tears, stands up to weathering and breakdown from sunlight exposure, and maintains resilience over prolonged pressure.

Silicone: Also resists breakdown from sunlight exposure and maintains resilience over prolonged pressure. Has a longer lifespan than EPDM, more stretchy, and much better in locations where it might get hot (EPDM can fail at 130 degrees).

Each rubber breaks down when it gets too hot and each becomes brittle when it gets too cold.

Question 5

What is the difference between a curtain wall and storefront?

Answer 5

Curtain wall: glazing system hangs like a curtain to create the exterior skin of a building, outboard of the floor slabs. Often multiple stories tall (multi-span); higher design wind pressures. More expensive

Storefront: aluminum and glass framing system that sits inboard of floor slabs. One story (single span) max, often for the first floor only in commercial construction. Less expensive.

Crews erect and glaze both on site; curtain wall can be unitized in the shop and field-erected. Either one can be reinforced with steel In the framing cavity if loads are excessive.

Question 6

Mullion detail

Answer 6

Gaskets provide the thermal break; glass-to-aluminum clearance provides the spacing needed for seismic shifting.

Question 7

How do we reinforce storefront window frames?

Answer 7

With steel enclosed in the aluminum, when structurally necessary.

Question 8

Draw a window section detail for a masonry wall

Answer 8

For masonry wall

Question 9

Draw a window section detail for a stick-built wall

Answer 9

For stick-built wall

Question 10

Draw a vertical shaft wall detail in stick-built wall construction

Answer 10

Vertical shafts are required for ducts, pipes, conduits, etc. traveling from floor-to-floor; and for elevators and stairwells. Because if compromised they could easily spread fire and smoke from one floor to the floors above, they require a significant fire rating, necessitating construction of concrete, concrete block, or as many as five layers of especially-fire-resistant gypsum board in plan (“type X” gypsum board or “type C” gypsum board”). Penetrations, are minimized, and detailed to maintain the required fire rating (often two- three- our four-hour rated). Mechanical shafts are often non-load-bearing. The plan detail is below.

Because the fire protection must be maintained continually up the shaft, and builders may have difficulty screwing gypsum board to the inside face of the shaft wall when building from the room outside the cavity, we’ve developed techniques to affix fire-rated “gypsum liner” panels on the inside of the cavity wall from outside of the shaft. See this video.

See this video too if you’re still not sure how this works.

Question 11

Expansion joint detail vs a control joint detail

Answer 11

A control joint is a shallow groove in concrete to control cracks from shrinkage.

Cutting a control joint with a saw (scoring one, really):

Control joint video

Relish the drawing of necessary control joints, because if you don’t lay them out, someone else will do that task poorly. Note that this curb cut control joint almost–but not quite–aligns with the 16-square brick pattern.

Question 12

Expansion joint detail vs a control joint detail

Answer 12

An expansion joint extends the full depth of the building assembly, creating two independent structural elements. When part of the building expands, it won’t push on the other. The gaps between the elements are filled by a squishy material (bitumen, fiberboard).

*Important for CE exam as well.

Question 13

ADA-compliant room name signs: what height above the floor?

Answer 13

An ADA sign might denote that there is an exam room just on the other side of a door. Installation height: Max 60” to top line of tactile text; Min 48” to bottom line of tactile text; anywhere in between is okay.

Question 14

ADA-compliant room name signs: location

Answer 14

Location: Latch side of single door; inactive leaf of a double door with an inactive leaf; to the right of the right-hand door of a double door with two active leaves; if there is not enough room next to the door, you may place the sign on the nearest adjacent wall.

See this video.

Question 15

What is a “collector” in seismic design?

Answer 15

The floors and roof of a building form diaphragms, horizontal-resistance membranes important in seismic design that transfer lateral earthquake forces. Collectors (also called drag struts or ties) “drag” diaphragm shear forces from diaphragms to vertical resisting elements. In practice the collectors themselves look like sheet metal brackets or pneumatic shock absorbers that attach the floor of one part of a building to the wall of another.

The component parts of irregularly-shaped buildings (i.e. both wings of an L-shaped building) sway in an earthquake out of phase with one another. Detailing each building part as its own structure, and connecting the parts with ductile metal, employs a “bend but don’t break” strategy, making the joint between the parts less brittle.

Question 16

What is a “collector” in seismic design look like?

Answer 16

The floors and roof of a building form diaphragms, horizontal-resistance membranes important in seismic design that transfer lateral earthquake forces. Collectors (also called drag struts or ties) “drag” diaphragm shear forces from diaphragms to vertical resisting elements. In practice the collectors themselves look like sheet metal brackets or pneumatic shock absorbers that attach the floor of one part of a building to the wall of another.

***These are also called “drag struts” or “drag trusses” (remember that)

Question 17

How do you separate floors with different occupancies in mixed use buildings?

IBC Section 508 addresses mixed uses and occupancies. Sometimes different occupancies within a building are considered by the code to be “separated” and sometimes they are considered to be “non-separated.” We achieve separation with a fire-rated wall or floor-ceiling assembly. See the table. The “S” column is used for sprinklered buildings and the “NS” column is for buildings without a sprinkler.

Answer 17

Sometimes there is no fire-rated barrier required by the code to separate different occupancies. This is indicated by an “N” in the cell that aligns with the two different occupancies under consideration. For instance, looking across the first row of the table, there surprisingly appears to be no fire rated separation requirement for a theater (group A-1 “assembly” occupancy) that shares a wall with foundry (group F-2 “factory industrial low-hazard” occupancy), provided that the building is sprinklered. If the building is not sprinklered, there would be a requirement for a one-hour-rated wall. There are of course other, acoustic, reasons why these two spaces shouldn’t share a wall.

Some adjacencies are not permitted no matter how fire-resistant the wall or floor-ceiling assembly is constructed. These have an “NP” in the cell. This is the case with a parking garage (group S-2 occupancy) below a drug detox medical facility (group I-2 occupancy) in a building without a sprinkler system.

Question 18

What is the difference between internal and external metal roof flashing?

Answer 18

External roof flashing is laid on top of shingles in valleys and along peaks. Internal flashing is installed under the roof shingles. Counterflashing (or cap flashing) is the first line of defense when shedding water off a parapet. It attaches to parapet wall with sealant (to prevent water from penetrating behind the flashing) and laps the step flashing. In high wind applications, use flashing with clips so it doesn’t rip off the wall.

Question 19

Flashing and sealing where the parapet meets the roof

Answer 19

Flashing and sealing where the parapet meets the roof. The counterflashing allows the roof membrane to be replaced more easily.

Question 20

Delayed egress locking systems

Answer 20

In retail, these delayed door panic hardware systems prevent shoplifters from running out of the emergency exit because an alarm sounds and the door doesn’t let the perp out of the building for 15 seconds after they lean on the hardware bar (30 seconds when an exception is granted). Delayed egress locking systems can also be used for other security-sensitive applications such as airports, warehouses wary of employee theft, and nursing homes fearful of wandering dementia patients. They are only permitted in buildings outfitted with sprinkler systems or automatic smoke or heat detection. That way, when the automatic sprinkler system, smoke detection system, or heat detection system is activated, the delay in the system that prevents fleeing occupants from immediately exiting is deactivated automatically and occupants can easily leave without waiting in a real emergency. The delay also can be deactivated by a loss of building power or manually by the fire command center. Delayed egress systems are not permitted in occupancy groups

A (assembly): we don’t want the first occupants out of a burning theater to be crushed against a door that won’t open by the panicked pushing of those fleeing behind them.

E (K-12 education): I don’t know if this is school-shooting-related, or, like the assembly exception, related to the potential for crushing and trampling.

H (high hazard): You need to be able to get out of the gunpowder factory without ever waiting 15 seconds.

In each exception, the possible security benefit of the delay is outweighed by the life-safety benefit of easy exit.

In I-2 (detox facilities, psych hospitals) and I-3 (prisons) a second (but not a third) delayed egress door is permitted as part of the egress path.

To see an demonstration video, go here.

Question 21

Unit cost vs unit-in-place cost

Answer 21

Both these terms, unit cost and unit-in-place cost, mean (just about) the same thing. The “unit cost” usually refers to construction cost estimating during design and bidding and “unit-in-place” is a term usually reserved for appraisers estimating the worth of a building someone is looking to purchase, refinance, insure, or account for in an audit.

The unit cost method estimates building budgets or construction costs by breaking down the project into smaller parts, estimating the cost of each of those parts, then multiplying that unit cost by the number of parts (units) in the project. In early design, the “units” may be square feet of finished space. One might make an estimate by taking a $600 per square foot guess (unit cost) and multiplying that by the 10,000 square feet in the project to reach a budget of $6,000,000. Later in the design process (PDD world) the estimate is based on more detailed information: the linear feet of pipe multiplied by the approximate installed cost per linear feet of pipe, plus the number of faucets times the average price of an installed faucet, plus. . . . and so forth for the rest of the project. These spreadsheets may swell in length.

Unit-in-place cost method does the same thing–separate all the components of a building, estimate the cost of each unit (in cubic feet of concrete, square feet of paint, linear feet of foundation, number of theaters in the multiplex, number of roofs on the campus, or number of exterior doors on the warehouse) and multiply that unit cost by the number of units on the property. . . , then add everything up to reach a total value for a property appraisal.

Question 22

Door signage locations

Answer 22

Watch this online video here

Question 23

Name the lock type: door that never locks, like when you need to maintain egress

Answer 23

Passage Latch: The latchbolt is retracted by the lever or knob from either side, always (lever meets accessibility and knob doesn’t, but the knob is drawn here for clarity)

Question 24

Name the lock type:

• Outside is locked by an inside thumbturn
• Turning the inside lever or closing the door automatically unlocks the outside lever
• If you are locked out, an emergency specialized key can get you back in.

Answer 24

Bath/Bedroom Privacy Lock

Question 25

Name the lock type:

• A key outside, or inside thumbturn locks/unlocks the outside lever
• The inside lever automatically retracts the latchbolt for egress.

Answer 25

Office and Inner Entry Lock

Question 26

Name the lock type:

• A key locks/unlocks the room from the outside
• The inside lever automatically retracts the latchbolt for egress.

Answer 26

Classroom Lock

Question 27

Name the lock type:

• A key locks/unlocks the room from the outside and the key also locks/unlocks the room from the inside
• The inside lever automatically retracts the latchbolt for egress.

Answer 27

Classroom Security Lock

Question 28

Name the lock type:

• The door is unlocked by a key outside
• The outside lever is continuously locked by 24 volt AC or DC current
• An electrical switch or power failure unlocks the door remotely
• The inside lever automatically retracts the latchbolt for egress.

Answer 28

Electrically Locked (Fail Safe)

Question 29

Name the lock type:

• The door is unlocked by a key outside
• The outside lever is continuously locked but can also be unlocked by a 24 volt AC or DC current
• An electrical switch unlocks the door remotely, but in a power failure, the remains locked
• The inside lever automatically retracts the latchbolt for egress.

Answer 29

Electrically Unlocked (Fail Secure)

Question 30

Name the lock type:

• The door is unlocked by a key outside
• The outside lever is inoperative
• The inside lever automatically retracts the latchbolt for egress.

Answer 30

Storeroom Lock

Question 31

Which type of pipe expands more when hot water flows through it: Metal or Plastic?

Answer 31

Answer: Plastic

Question 32

What does this very-heavy dashed line inside the wall mean?

Answer 32

That wall is fire-rated and is part of a life safety strategy of separation to keep the fire contained, for a while, in just one part of a building.

When a duct passes through that rated wall, a smoke damper, electronically tied to the smoke detectors, is required that will choke off the air (and smoke) passing from one side of the rated wall to the other. Gaps in the wall that arise as part of the expediency present in any construction project will need to be filled with appropriate firestop (a putty often red in color) as will penetrations in the wall for conduit, pipe, and ductwork. And the wall itself will either be constructed of a fire-resistant material such as concrete or CMU, or is likely to have multiple layers of gypsum board on each side to achieve a required one-, two-, three-, or four-hour rating.

This example, which is also red in the digitally-submitted CD drawing set, depicts a one-hour rated wall because the number “1” sits between the dashes in the long-dashed line. Were it a three-hour rated wall, the pattern would be dash-3-dash-3-dash. . . This particular wall requires a fire rating (as does the ceiling) because the restaurant is classified as an assembly space and apartments populate the rest of the building, both adjacent in plan and above in section. The short-dashed portion of the red line on the top of the plan denotes a “water curtain,” which is just what it sounds like: close together special sprinkler heads that make a wall of water to maintain the fire separation. Available but atypical, it was required here because, to earn the historic tax credit, an existing portion of the glass vestibule had to remain intact, and because the ramp just plan-north of the water curtain is part of the apartment egress, this ramp has to be fire-separated from the restaurant.

Question 33

Describe the difference between the following types of specifications:

Performance

Prescriptive

Proprietary (closed)

Proprietary (open)

Reference

Descriptive

Answer 33

Specs may be written in different formats, but are typically written as a combination of the following:

Performance-based specs describe the way the product will perform without calling out a specific manufacturer, for example, “fasteners must be able to withstand a wind load of 110 mph.”

Prescriptive specs describe the construction means and methods, for example, the composition of the concrete mix.

Closed Proprietary specs name the specific manufacturer, and don’t allow substitutions, for example, “CR Laurence Co Double Seal Spacers, in dark bronze and with a dual seal, catalog number 3455590 shall be used at stairwell windows”

Open Proprietary specs also name one product from one manufacturer as the basis for design, but they allow other products as acceptable substitutions. Substitutions are processed through the General Requirements substitutions procedures in Division 01 of the spec set.

Reference specs demand the product or installation meet the requirements laid out by a trade association, government agency, or other industry reference standard, for instance, “Scaffolding must meet requirements as laid out in ANSI ASC A14.2,” or, “Clay brick conservation treatment must meet requirements as established in the National Research Council Canada National Master Specification, section 04 04 21.19.”

Descriptive specs are a hybrid of performance and prescriptive specs. They describe the way the product will perform without calling out a specific manufacturer, but are likely to also include clauses detailing specific means and methods of construction. For instance, a descriptive specification might both establish the strength of the mortar, and establish the water ratio in a mortar mix to be used.

*Often specs fall into more than one of these categories. For instance calling out a specific products and accepting substitutes that meet a standard and prescribing the mean and methods of installation.

Question 34

What is CSI Masterformat?

Answer 34

Masterformat is a system for organizing construction documents, specs, contracts, and operational manuals. Published by the Construction Specification Institute (CSI), it allows, for instance, a fire sprinkler subcontractor to easily find the relevant sections of a building’s documents so a requirement is less likely to be overlooked when bidding, purchasing a product, or during construction. There are 50 numbered divisions, ranging from Instructions for Procurement (found in Division 01) to Fire Suppression Sprinkler Systems (found in Division 21). Masterformat is especially useful for systematizing spec writing, as specifications may easily reach thousands of pages in length in a medium-sized building project. When using Masterformat—which is typically, though not always, utilized on a medium-sized or large project—know that the table of contents alone is nearly 200 pages! If the drawings are the broad intention of a building, specs act as the fine-print, establishing the scope of the work, the materials and methods of construction to be used, and the quality of the workmanship expected. Spec-writing is important to the project, though tedious. Some firms write their own specs in-house, and others hire a professional architectural spec writer. Once a thriving category of consultancy, human spec writing is now waning, gradually being replaced by digital tools: Google searches or links to product information within a BIM file.

Question 35

What percentage of light that comes out of the fixtures, actually makes it to the desk height in a classroom?

Given:

2 lamps per fixture

2500 lumens per lamp

Light loss factor (LLF)= 0.60

Coefficient of utilization (CU) = 0.65

24 fixtures in the room

Room dimensions: 20’ x 30’

Foot-candles=(lamp lumens) x (lamps per fixture) x (number of fixtures) x (CU) x (LLF)/(area in sq ft)

Answer 35

A: 39%

Note that I’m not looking for the illuminance in foot-candles, and know that there is more information given than you need to calculate the answer.

Coefficient of utilization (CU), which ranges from 0 to 1, is the fraction of light that reaches the desk plane because of losses as the light reflects off surfaces. So a black room with lots of surfaces will have a lower CU value and a space with minimal white surfaces will measure a higher CU value.

Light loss factor (LLF), which also ranges from 0 to 1, is the fraction of light that reaches the desk plane because of losses from dirt inside the fixture and from the lamp dimming over time through lamp “depreciation.” So a room with a regular lamp wiping regimen and lamps that lose very little light over time will have a high LLF value and a dusty room with lamps that depreciate rapidly will have a lower LLF value.

In this case because the CU=0.65 we are only left with 65% of our light after we account for the reflection off the room surfaces on the way down to the desk. . . And because our LLF is 0.60, we then have only 60% of what is left after adjusting for CU when we account for the light lost in the old lamp and the dirty fixture. So we are looking for 60% of 65% of the light reaching the desk . . . 0.60 * 0.65 = 0.39. That’s our answer: only 39% of the light at the top of the room makes it down to the desk! 61% is lost! It is not uncommon for that much of the light energy to be lost before it reaches the desk.

Question 36

Wall A has a sound transmission loss (TL) of 60 in the opaque portion and five percent of the surface of the wall is covered by window (TL of 25).

Wall B has a sound transmission loss of 40 for the whole assembly (there is no window in Wall B)

Which will do a better job keeping passing bus noise out of the apartment, Wall A or Wall B?

Answer 36

Wall A has a sound transmission loss (TL) of 60 in the opaque portion and five percent of the surface of the wall is covered by window (TL of 25).

Wall B has a sound transmission loss of 40 for the whole assembly (there is no window in Wall B)

Which will do a better job keeping passing bus noise out of the apartment, Wall A or Wall B?

Answer: Wall B

To calculate Wall A TL

TL₁-TL₂ = 60-25 = 35, which is the difference between the acoustical performance of the opaque portion of Wall A and the performance of the window portion, given that only five percent of the wall is window.

From nomograph here in red. . .

TL₁-TL_c = 22, which means that the window knocked 22 points off the TL rating of the composite wall. 60-22=38 so the composite wall is 38, which is FAR lower than the 60 we started with on that wall, even though only 5% of the wall surface is window! It’s almost always about the window, not the wall!

The composite TL of Wall A, then, is calculated at 38.

The TL of Wall B is given at 40, and there is no window.

So Wall B, the one without the window, performs (moderately) better than Wall A, even though 95% of Wall A is so much more robust.

Question 37

Circuit A is 240 volts and 4000 watts

Circuit B is 120 volts and 500 watts

Which circuit needs a thicker wire? Given:

W=I*V

Answer 37

Answer: Circuit A

W=I*V

Circuit A

4000w = I * 240V

4000w/240V = I

I=17amps

Circuit B

500w = I * 120V

500w/120V = I

I=4 amps

More current (measured in amps and denoted by “I”) needs thicker “pipes” (thicker wire). If the wire isn’t thick enough, it becomes hot and can start a fire. So Circuit A, because it runs with more current, needs a thicker wire.

As an aside, wire thickness—like many metals used in building– is measured in gauge number. . . And counter-intuitively, a lower gauge number translates to a thicker wire.

Question 38

The pressure in a city water main is 50 psi. The pressure loss through piping, fittings, and the water meter can be ignored for this exercise. What is the height above the water main, above which the water will not flow? Given:

h=2.3 psi

Answer 38

Answer: 115’

h=2.3 P

h=2.3 * 50psi

h=115’

So if you extend a pipe to 116 feet higher than the water main, there will be no water pressure at that altitude in that pipe. You could look down inside that 116-foot-high pipe and see the top of the water column one foot down into the pipe, but the pipe could be uncapped and water wouldn’t flow out of it.

*A similar formula 1 psi = 2.31 feet of water can be found in the exam by clicking on “References” on the top bar and then clicking on the “Plumbing” tab. You can practice on the NCARB demonstration exam, which is found on the right side of your my NCARB page. In 2021, NCARB began minimizing the importance of the reference tabs in the exam and prioritized including relevant reference material and formulas INSIDE the relevant test item question instead.

To watch an Amber Book 40 Minutes of Competence video solving this problem, click here.

Question 39

Non-load-bearing exterior walls may require a fire rating. The type of fire rating (one hour, two hours, etc.) is based on the _______.

Distance between your building and the property line

or

Height of your building

Answer 39

Answer: Distance between your building and the property line

The fire rating of exterior walls is based upon fear that your fire will spread to the adjacent buildings. It is determined on Table 602 “Fire Resistance Rating Requirements for Exterior Walls Based on Fire Separation Distance.” Besides the distance to the property line, the fire rating of the exterior wall is governed by the construction type (non-combustible concrete buildings can sometimes have a lower fire rating in the exterior wall); and further controlled by occupancy type (high- and medium-hazard buildings, factories, and retail (with lots of content to burn) may require more fire-resistant exterior walls). See here (and scroll down to Table 602).

Load-bearing exterior walls must also comply with the fire ratings set forth in Table 601. Those parameters serve a different purpose: not so much to prevent fire from spreading to the neighbors, but rather to make it less likely that your building will collapse once on fire.

Question 40

A bank shares a wall with a courtroom in an unsprinklered building. That wall must be rated to _______ hours. (You may use the internet or the Amber Book Case Study material to answer this question.)

No rating required (0 hours)

A 1-hour fire rating

A 2-hour fire rating

A 4-hour fire rating

Answer 40

Answer: A 2-hour fire rating

You’ll search the case study (seehere for a substitute) for “bank” and “courtroom” and see that the bank has an occupancy classification of Business (B) and a courtroom has an occupancy classification of Assembly (A-3). Then you’ll search for the adjacency table called Required Separation of Occupancies (Hours): Table 508.4. You can gohere for that now, but if you don’t remember a good search word like “separation” while in the testing center, scroll down through the case study until you find it. Confusingly, that table has four classifications, three of which begin with N:

N= No separation requirement

NP=Not permitted (meaning the two adjacencies may not be adjacent!)

NS=No sprinkler system

S=Sprinkler system

1=One-hour fire separation required

2—Two-hour fire separation required, etc.

To watch me solve this problem in an Amber Book : 40 Minutes of Competence video, click here.

Question 41

Which pipes create less friction?

Copper

Plastic

Steel

Answer 41

Plastic

Question 42

So much information! I’m having trouble memorizing all of this. What should I do?

Answer 42

As with any test, memorize what you think you need to, but recognize that you will not be able to recall everything, and be okay with that. This is why it is most important to own the concepts: so that you can answer even the content you didn’t study (or forgot). If you are having trouble remembering, practice putting the content into your own words. Taking notes using my words is not effective for long term recall: it is just glorified highlighting.

And know that this is a long course because it is comprehensive. If you generally understand the content in Amber Book, I don’t think that you need other material to get to a place where you are likely to pass these exams. You don’t need practice tests (beyond NCARB’s Demonstration Exam). If you’ve already taken an exam division, ask yourself: Did I answer a test item incorrectly because I didn’t understand the exam format? Or did I answer a test item incorrectly because I didn’t understand the exam content?

Question 43

A horizontal wind force of 3,840 pounds is acting on a wood shear wall with a uniform gravity load of 1,000 pounds per linear foot on top of the wall. The wall height is 35’ . Calculate the minimum length of the wall so that it will still behave as a shear wall and resist the lateral loads.

Answer 43

Minimum length of 10’

As shear walls shrink in length and get taller, they behave more like columns and less like shear walls–and are unable to resist lateral loads from wind or seismic forces. We need to establish a maximum aspect ratio for tall, thin, shear walls, beyond which the panel action of the wall in resisting horizontal loads can no longer be trusted to stabilize the building.

The gravity load on the top presented in this problem isn’t relevant to this calculation. Prescriptive code requires a maximum shear wall aspect ratio (height:length) of 3.5:1, provided the shear wall is made of something stiff (like structural fiberboard). This maximum drops to 2:1 for a less-stiff wall (like blocked particle board), so if the shear wall were less-stiff, our minimum wall length would be one-half of the 35’ height, or 17.5’. With a stronger wall assembly, we can get the wall thinner: 3.5:1 or 10’ long, which is our answer. When using the prescriptive code, the horizontal force is also redundant.

The above are based on rules-of-thumb. There are at least three different math-based alternatives to calculate the minimum length if the wall has openings for windows/doors, but for a basic un-perforated wood wall, we can simply divide the horizontal wind force of 3840 pounds by 320 pounds/foot to derive a minimum wall length of 12 feet. Where did the 320 number come from? You’d need to look it up in a table (not given in this problem) defining allowable shear forces for different constructions. This is likely beyond what the ARE would ask of you, but I include it here for those who are curious.

In practice, a shear wall in wood construction is almost always built as follows. OSB on one side of the exterior stud wall (that doubles as enclosure sheathing) with horizontal blocking framed so the OSB edges have something to nail into: that way when the wall is pushed horizontally, the free edges of the OSB panels won’t buckle. Framers nail the perimeter of the OSB six inches on-center and the middle of the OSB at 12” O.C.; and they affix hold-down anchors at the ends of each segment so that the wall doesn’t peel off the foundation when exposed to the lateral loads that the wall intends to resist.

Code limits masonry shear wall aspect ratios (height:length) to 2:1, and concrete and CLT have aspect ratios defined by other tables and calculations.

As you may imagine, this is a complex subject– see here if you are curious to learn more (not necessary for your ARE studying).

Question 44

Are fire-rated barriers (walls or floor-ceiling assemblies) required between “nonseparated” occupancies?

Answer 44

No (not usually).

If two occupancies are considered nonseparated, the barriers between them needn’t be rated unless they are dwelling units (apartments), sleeping units (hotels) or similar residential (R) classifications–which do require fire-rated barriers. And as is often the case, prisons (I) and fireworks storage facilities (H) are also exceptions–and also require fire-rated separation.

Question 45

Incidental use vs. accessory use in the code

Answer 45

Incidental use example: An accountant’s office (occupancy class B) includes a boiler room or other space that poses a greater life-safety risk than posed by the office. Provided that the boiler room does not exceed 10% of the story’s floor area, the boiler room can be counted with the office in the less-stringent B-classification. . .but the more dangerous boiler room requires fire separation in the form of fire-rated walls and floor-ceiling assemblies (and/or sprinklers). It is not up to the architect to decide what can be considered incidental use (though it used to be in older code versions). Rather, the code maintains a list of such high-risk-but-small-area rooms it considers “incidental,” such as refrigeration equipment rooms, laboratories, paint shops, and large laundry rooms.

Accessory use example: An accountant’s office (B) includes some storage (usually S, but not considered separate here). If the storage is for the accountant, and not on the list of small-but-risky incidental use spaces, and less than 10% of the floor area of that story, it doesn’t have to be counted as a different occupancy classification. . . and therefore doesn’t require a fire rated wall separating the storage area from the office around it.

Question 46

Define nonseparated occupancy vs separated occupancy in the code

Answer 46

Nonseparated occupancies example: We’ll use the same accountant’s office (occupancy class B), but this time the storage area (S) exceeds 10% of the story’s floor area or the storage area is used not by the accounting office, but rather by the landlord, who has an eBay business and likes to keep his merchandise in the storage room. For either of these reasons, we can’t classify the storage area as an accessory space. We have two options instead. We can deem them “nonseparated” B and S occupancies, or we can deem them “separated” B and S occupancies. The nonseparated flavor often, but not always, allows for a less expensive alternative. You typically wouldn’t have to design fire separation between the B and S areas in nonseparated construction, however when you determine area limits, height limits, and construction type, you would have to treat the whole building as if it were the more restrictive of the two occupancy types. In this case, the whole building’s construction type might have to be designed to a higher S standard, instead of a lower B standard.

Separated occupancies example: Here, again, the storage area exceeds 10% of the floor’s area or someone other than the accountant uses the storage area. We have the option of declaring the B and the S as “separated” occupancies and, as such, we may have to build fire-rated walls and floor-ceilings between them. The B and S areas each comply with the code based on their respective occupancy classification. Construction type here (and area limitations) would be based on the proportions of the building that fall under each type of classification. You can see how this may, or may not, work out to your advantage. In some cases the cost of building fire separation within the building’s different occupancies exceeds the cost of the limitations on whole-building construction type (and you’ll choose to pursue nonseparated occupancy status); in other cases the cost penalty of within-building fire separation pales relative to limitations of whole-building construction type (and you’ll go with separated occupancies instead). In short, either don’t separate the rooms and build the whole building to the more strict standard, or separate the rooms and build each part of the building to its own standard.

If you are still unclear, see this video I made.

Question 47

The top of the municipal water tank sits 115 feet above a fixture. The pressure loss through piping, fittings, and the water meter can be ignored for this exercise. What is the water pressure at the fixture?

Given: 1psi = 2.31 ft of water

Answer 47

50psi

http://flashcards.amber-book.com/wp-content/uploads/2020/06/Plumbing-Pressure-Video.mp4

Question 48

Why do we need shear walls?

Answer 48

See Video

Question 49

What is the cost of heating a building with a natural gas boiler, given . . .

Peak heat loss = 500,000 BTU/hr

2,000 Full-load hours/yr

Fuel heat value of natural gas = 1,000 BTU/cu ft

Fuel cost = $11 per thousand cubic feet of natural gas

Boiler efficiency = 90%

Answer 49

A: $12,222

given . . .

Peak heat loss = 500,000 BTU/hr

2,000 Full-load hours/yr

Fuel heat value of natural gas = 1,000 BTU/cu ft

Fuel cost = $11 per thousand cubic feet of natural gas

Boiler efficiency = 90%

Now to solve. . . .

Question 50

Where is an outdoor transformer located when the power is buried underground? Where is the switchgear located for that same building?

Answer 50

Underground power lines are typically buried in a line 4’ inboard from the street property line. Outdoor transformers for underground power lines are often on the property line that separates your building from your neighbor’s building, 4’ in from the street.

Switchgear is located right at the point where the power enters the building, so inside the wall closest to the transformer.

Question 51

RMC vs IMC vs EMT vs GRC conduit

Answer 51

These are classifications of conduit wall thickness.

Rigid metallic conduit (RMC): Thicker. Normally threaded.

Intermediate Metal Conduit (IMC): Medium thickness. Also threaded.

Electric metallic tube conduit (EMT): Thinner, and sometimes called, “thin wall” in the field. Too thin to be threaded. Used for smaller (branch) circuits and not designed for robust connections to the conduit upstream and downstream. Less expensive.

Galvanized rigid conduit (GRC): Galvanized for corrosion resistance and thick enough to be threaded.

Question 52

Locate and draw the rain control, air control, thermal control, and vapor control on this masonry-facade wall section. You’ll need to add the stone to the drawing too, as the drawing only includes the steel structure. Draw the one that works best for all climates.

Answer 52

https://flashcards.amber-book.com/wp-content/uploads/2020/10/Enclosure.mp4

Question 53

How do you detail a lintel on an exterior load-bearing masonry wall?

Answer 53

1. Lintel can be precast concrete, site-cast reinforced concrete masonry block (lintel block or bond beam block filled with rebar and concrete), stone, or metal. It spans the opening over the door or window, distributing the loads around the opening.
2. Lintel must overlap the jamb by six inches so that it has enough wall on each side to bear on. See here.
3. Lintel should have a membrane and weep holes so that the water that moves behind the cavity wall will be properly redirected out of the cavity wall when it meets the lintel. See here.
4. Don’t design a point load to fall on the flange (thin, non-structural part, seen here between points B and A) of a metal lintel. It will deform it.
5. Lintels are prone to thermal bridging. Design them so that the inside and outside portions are separate elements or have insulation. See here for an example.

This is a great (short) video on the subject if you are confused by the list above or want to learn more.

Question 54

What is panic hardware? Where is it required?

Answer 54

Panic hardware allows throngs of scared people to run into a door. . . and the door opens from the pressure on a bar, without turning a lever. You’ve seen it a million times, and it looks like this.

It is required in assembly, educational, and high-hazard occupancies with an occupant load of more than 50 people.

Question 55

I want to purchase a smaller air conditioner than the one needed for my current building design. How can I reduce peak radiant solar window heat gain by 6,000 btu/hr?
Given: 100sf of west-facing window (no other windows)
Solar heat gain coefficient (SHGC) of glass: 0.80
R-value of glass: 2.3
Infiltration of windows: 0.1 cfm/sq ft
Peak solar radiant heat striking the outside of the glass: 150 btu/sf*hr
Outside summertime design temperature: 92 degrees F

Answer 55

Reduce solar heat gain coefficient (SHGC) to 0.4 or eliminate 50sf of window

Because this question is dialed in on peak radiant gains only, the information given on conductive gains (R-value, outside design temperature) can be ignored. That distractor information deals with molecules dancing through the solid glass.

For the same reason, the givens concerning convective gains (infiltration rates, outside design temperature) can be ignored too. Those distractors concern fast-dancing molecules outside slipping inside through cracks at the seams of the glass.

The problem explains the sun to be 150btu/hr per square foot of glass

Multiplied by 100 sf returns 15,000 btu/hr striking the outside of the glass

Multiplied by 0.80 SHGC suggests 12,000 btu/hr of peak summertime radiant gain inside the rooms currently

Because we need to eliminate 6,000 btu/hr—half of the 12,000 btu/hr current solar gain—we can halve the SHGC to 0.40, which means adding a low-e film to our windows. . . or we can halve the area of windows to 50sf, or plant a tree to shade the window, or add louvers to shade the window.

Want (or need) to do it again? Watch this Amber Book : 40 Minutes of Competence video where I ask and answer a similar question. Be sure to hit pause and answer it yourself before I go over the answer. . . attempting to answer questions yourself is where all the learning and long-term recall happens.

Question 56

What is mastic?

Answer 56

Construction adhesive and sealant

Question 57

Describe everything water touches on it’s way out of a wall cavity, as it moves from the sheathing’s waterproof layer to the outside

Answer 57

1. Waterproof layer on sheathing (could be lapped tar paper, lapped Tyvek, peel-and-stick membrane, or fluid-applied waterproof coating)

2. Mastic (asphalt-based goo that seals the flashing to the sheathing). See here for an example. If the structural wall is constructed of CMU, then the flashing may be tucked between courses instead. See here for an example.

3. Metal or peel-and-stick membrane flashing to redirect the water to the outside of the cavity. See here for an example.

4. Weep holes to air the water to the outside. See here for an example.

Workers installing rain screen panels to hat channel to create a rain screen with a capillary break.

Question 58

Mastic and weep holes in the shower

Answer 58

Mastic and weep holes are also in shower assemblies, which can be confusing, because those terms are used with flashing in cavity walls.

Weep holes are found in shower drains as alternative paths for water to move down the drain. They allow under-floor water that has seeped through the tile grout and joints to find its way back to the drain. See this video.

Tile mastic and thinset are the two most common options for affixing tile. Mastic, originally an organic resin from a Mediterranean plant, is now a catch-all term for sticky stuff that dries quickly (useful for affixing vertical tile so it doesn’t sag while drying). Mastic, as applied to tile laying, is a term that has largely been phased out and replaced with “fast-grabbing tile adhesive,” “no-sag tile adhesive,” or just “tile adhesive.”

Thinset is a cement product. It takes longer to set, which can be a good thing, or a bad thing, depending on whether you want the tile to stay put without having to hold it for a while, or you want the flexibility to reposition the tile later. Thinset can also be used to lay vertical tile, but is always used to set horizontal tile in showers. Unlike mastic, which can get damp and still hold, thinset can remain submerged in water and still perform. So, to get the terms straight. . .

“Thinset” and “mortar” and “thinset mortar” are interchangeable terms. Like the stickier “mastic,” which is interchangeable with “adhesive” they are what hold the tile to the floor, ceiling, wall, or backsplash. Grout is the stuff that fills in the spaces between tiles. Grout, which is also a cement product, but one with a different chemical mixture than thinset mortar, provides additional tile bonding and protects the edges of the tile from chipping. It is used always between the tiles, regardless of whether the tile was affixed with thinset mortar or mastic adhesive.

Question 59

Reinforcement for masonry block in seismic zones

Answer 59

There are two types of masonry block walls with different sets of rules in seismic zones: those that are part of the seismic force-resisting system (load bearing, shear walls) and those not part of that system (partitions, non-load-bearing).

Seismic force-resisting system: The level of reinforcement depends on the seismic design category, which in turn, depends on the risk and is determined by map (see here for the map. . . who knew that coastal South Carolina was so at-risk for a major earthquake?!). Walls should be structurally tied together at corners to add stiffness to the building to prevent this from happening. Reinforcement requirements are very specific to level of risk, and not worth memorizing, but generally fall under the concept. . . .

Low seismic risk: reinforcement extending the full height of the wall, through the foundation to the top of the wall every ten feet vertically and at jambs, reinforcement extending the full width of the wall every ten feet horizontally, and local reinforcement at lintels. Reinforcement around the wall’s perimeter. See this elevation.

High seismic risk: reinforcement extending the full height of the wall, through the foundation to the top of the wall every four feet vertically and at jambs, reinforcement extending the full width of the wall every four feet horizontally, and at lintels. Reinforcement around the wall’s perimeter. See this elevation.

Why all the reinforcement? We’re trying to prevent this from happening (in the third image, the damage to the wall is in the lower-right corner).

What does “reinforcement” mean in the context of block walls? See here for low seismic risk. In high seismic risk, you’ll need bond beams for horizontal reinforcement. See here.

Block walls not part of the seismic-force-resisting system (non-load-bearing partitions): for these random partitions, instead of tying walls together at corners structurally, we want to isolate masonry walls at corners (the opposite of the requirement for load-bearing walls) so swaying in the adjacent wall doesn’t topple our wall where the two walls meet.

Reinforced CMU:

Question 60

Detail this parapet for

Rain control

Air control

Thermal control

And vapor control

Answer 60

http://flashcards.amber-book.com/wp-content/uploads/2020/10/Parapet-Answer-Video.mp4

Question 61

What is the minimum diameter the vertical drain serving a roof?

Given:

100 year hourly rainfall = 3 inches

Total roof area = 4,000 sf

2 roof drains (assume equal catchment areas for each drain)

7.5 gallon = 1 cubic feet

Answer 61

A: 3 inches is the minimum diameter of the vertical drain serving a roof

Detailed answer:

Given:

100 year hourly rainfall = 3 inches

Total roof area = 4,000 sf

2 roof drains (assume equal catchment areas for each drain)

7.5 gallon = 1 cubic feet

Each roof drain catchment area: 2,000sf

1/4 foot of rain per hour

So 2,000 sf * 1/4 ft = 500 cubic feet of rain per hour

Times 7.5 gallons/cu ft = 3,750 gallons per hour

Divided by 60 minutes per hour = 63 gallons per minute

Then look at the chart and see that a 3″ vertical drain pipe can handle 87 gallons per minute (but one size smaller can only handle 34 gpm)

Question 62

Describe, in your own words, a 1/4 bend fitting.

Answer 62

A bend is like a long-radius pipe elbow, and bends are measured in fractions of a full 360 degree turn. So a 1/4 bend fitting is a 90 degree pipe turn and looks like this. A 1/8 bend fitting redirects the pipe 45 degrees and looks like this.

An elbow turns in a tight radius, meets established dimensional standards, and measures in degrees.

A bend turns in a long radius, requires custom fabrication (and can therefore have any dimensions), and is measured in a fraction of a bend.

*in practice, plumbers may use bend and elbow interchangeably to describe the same fitting.

Question 63

What are the pros and cons of incandescent lamps?

Answer 63

Pros: Exceptional color rendition (chartreuse on the painting looks chartreuse to the eye); Interchangeable (if it looks like it screws in to the socket, it will work in the socket)

Cons: Inefficient! . . . about six times the power input required for the same amount of light output, relative to each of the lamps on the next few flash cards; Heats up the building

*halogen is a type of incandescent that burns whiter (less yellow), and most new incandescent lamps are actually the halogen flavor because they burn about 25% more efficient than traditional yellow incandescents.

Question 64

What are the pros and cons of fluorescent lamps?

Answer 64

Pros: More efficient than incandescents; longer life than incandescents

Cons: So-so color rendition; don’t work in cold outdoor applications

Question 65

What are the pros and cons of metal halide lamps?

Answer 65

Pros: Efficient, Long life; Bright (for high bays, big-box stores, factories, stadiums, and parking lots)

Cons: Long start times; Glare (for small rooms); So-so color rendition

If you forgot what metal halide fixtures look like, go here. The left side of the gym is LED and the right side of the gym is metal halide.

Metal halide fixtures:

Question 66

What are the pros and cons of LED lamps?

Answer 66

Pros: Very long life; Much more efficient than incandescents (about the same efficiency as fluorescents and metal halide); Improving every year (the future of almost all lighting applications)

Cons: Don’t work well unless they can conduct heat away from the electronics (that’s why the fins) so may not work as a retofit in your existing fixtures if those fixtures trap heat

See here for a comparison. The “CFL” label in the image stands for compact fluorescent lamp, a type of fluorescent with a built in ballast so that it can screw into a incandescent fixture.

Question 67

What are these black rings on the pipes for?

Answer 67

These pipe vibration isolators protect the downstream piping from most of the vibrational energy that would have otherwise been imparted to the building-wide chilled water piping system. They also help provide flexibility in pipe alignment tolerances in case the piping installers didn’t coordinate perfectly with the contractors who installed the equipment that will be tied to the piping.

Question 68

Specifications vs MasterSpec vs UniFormat vs the project manual

Answer 68

Specs (short for specifications): the fine print of your project. What gaskets may be used on the exterior doors. Developed by the architect, and the contractor is bound by what’s in there.

MasterSpec: Created in the 60s, it established a standard for ordering specs. . . a glorified, but useful, table of contents. . . what the Dewey Decimal System is for library books, MasterSpec is for specifications. . . .proprietary (created by a for-profit company) but created for the AIA, so it has wide acceptance and is fair game on the exams. . . the painter doesn’t need to look through 1,000 pages of specs to find out if he is allowed to paint the exterior today, despite the 49 degree temperatures outside. He knows just where in Masterspec he needs to go.

UniFormat: a competitor to MasterSpec. MasterSpec organizes the specs by material (sepcs on stone, specs on wood, etc.) and Uniformat organizes by system (specs on damp proofing, specs on spread footings)

Project Manual: Specs are a major part of the Project manual. The project manual also includes bidding requirements and contracts.

I keep giving you this image for a reason. . . learn it!

Question 69

How many phases is this circuit?

Answer 69

Answer: 3 phases

The three-pole circuit breaker switch suggests it serves a 3-phase 208-volt circuit or a 3-phase 480-volt circuit

For a video discussion of this topic, watch this Amber Book : 40 Minutes of Competence video.

Question 70

How many phases does this breaker switch serve?

Answer 70

Answer: A single-phase 240-volt circuit.

Don’t be fooled by the double-pole switch! These are two 120-volt feeds, in phase, tied together to create a 240-volt circuit. These two happen to feed a sub-panel on the other side of the basement (shown below). Other 240-volt, single-phase circuits in this house include the outside compressor/condenser unit, the inside air-handling unit, the oven, and the cooktop.

Study this illustration I made to remind you of what you learned in the videos:

Question 71

How do you prevent graffiti?

Answer 71

Urethane anti-graffiti coatings prevent graffiti paint from adhering to the surface. Graffiti cannot bond to the surface well, and if it does bond, the coating can be easily removed, taking away the graffiti with it.

Also. . .

Plant thorny bushes under the tempting facades

Remove graffiti as soon as it is discovered, as the tagger doesn’t want to go through the trouble if it will be removed soon, robbing him of his desired notoriety

Darker paint colors make graffiti stand out less, making it a less attractive surface

Install motion-activated lights

Question 72

Fire stopping vs fire safing

Answer 72

Fire-rated walls and floor-ceiling assemblies need a way to maintain their air-tightness at joints and duct/pipe/conduit penetrations.

Fire stopping: all the systems used to seal those small gaps and maintain the fire rating of the assembly

Fire safing: one of the types of fire stopping, it is a fire-resistant mineral wool insulation material that can stuff a gap to maintain the fire rating, like this.

See this excellent short video.

Question 73

Where to each of these go:

Transformer

Main distribution panel

Electrical meters

Answer 73

Transformer: Steps the voltage down to a safer level before it enters the building. They sit on the utility pole, in the ground near the properly line, or inside the building in a basement or utility room.

Main distribution panel: Divides the electricity into subsidiary circuits after the power enters the building. . . It says to the electrons, “You go to the restaurant commercial kitchen on the first floor and power the dishwasher; an you over there go to the apartment on the third floor and power four electrical receptacles and three light fixtures.” It houses the circuit breakers (fuses) that switch off if there’s overcurrent (dangerous short-circuit). It typically sits in a utility room or basement and can be small like this residential main distribution panel; or for larger buildings, it can be sizable like this.

Electrical meters: These let the electric company know how much power you use so they can bill you. You’ve seen them before (they look like this) and can be outside the building on a wall or inside, housed in a basement or utility room. Generally, if we have multiple tenants, we’d prefer to meter them separately so each can pay the utility company directly. Folks tend to leave the A/C on when they know that the landlord pays the electrical bill. Older buildings often have one meter for all the tenants, and the landlord pays the bill. Newer buildings have the utility monitor each tenant with a separate meter. In retrofits, sub-meters can bee installed so that the landlord pays the bill for the whole building based on the utility’s meter, and then collects electric from each tenant per the building’s sub-meter.

Electrical meter:

Question 74

Draw a canopy flashing detail

Answer 74

In new construction, flashing may be tucked into the wall assembly like this.

In an addition added after the building is constructed, we may seal the flashing too the wall. See this short video.

See here for flashing shapes.

Question 75

Wood frame shear walls

Answer 75

Short segments may need steel to make them stiffer

Blocking is required so that OSB panel edges have something to nail into

Hold-downs are required at ends of shear walls (or ends of shear wall segments if shear wall is perforated with windows or doors) to resist uplift forces, which are a result of the overturning (moment) force. Anchor bolts between the hold-downs carry the shear force. (In practice, a really tight hold-down will provide some shear resistance, but the main purpose is to keep the tension side of the shear wall from lifting)

Question 76

Which is better, face-sealed EIFS or drainage EIFS

Answer 76

Drainage EIFS is much better!

Exterior finish and insulation systems (EIFS) are the kind of synthetic stucco exterior finish that you see in shopping centers. It looks like this. In the 80s, builders started installing EIFS (pronounced EE-fiss) on residential projects. Because residential projects often have organic materials (wood studs, cellulose insulation), and because the EFIS was “face-sealed” without either a drainage plane capillary break behind it draining to weep holes or a rain-resistant layer on the exterior sheathing, trapped water didn’t drain and mold grew. The problem was especially acute in humid and marine climates (think Outer Banks, North Carolina). The 90s saw so much EFIS mold litigation that even obtaining an insurance policy on an EFIS building became prohibitive.

The solution? Add a drainage plane behind the insulation and in front of a lapped layers of building felt or house wrap. The new assembly is called “drainage” EIFS, it has become the standard, and the mold litigation industry no longer plagues EFIS construction. To read more, go here.

Face-sealed EIFS “stucco” wall (above)

Drained EIFS “stucco” wall (above)

North-facing EFIS often accumulates mildew:

If you start looking for it, you’ll see damaged EIFS everywhere:

In response, manufacturers began offering “impact-resistant EIFS,” more durable than standard EIFS, but still not as robust as other claddings. Because of this impact issue, you’ll often see the first floor clad with a tougher material, then EIFS up higher.

Question 77

What is the cross sectional size of a duct?

Given:

1400 feet per minute duct air velocity

3000 cubic feet per minute through the duct

Answer 77

A: 2.1 sf cross sectional area of duct (so, for instance, a duct 12 in high by 24 in wide)

To provide enough cooling (or heating) to a space, we send a given quantity of cooled (heated) air down the duct measured in CFM.

CFM = FPM x cross sectional area in sq ft

3000 cfm = 1400 fpm x cross sectional area in sq ft

cross sectional area = 2.1 sq ft

You don’t need to memorize this formula. . . to remember it when you need it, envision a duct with a one square foot cross-section and a 2 fpm duct air velocity:

As main ducts branch into secondary ducts, they generally become smaller in cross sectional area and slower in air velocity. Of course if each smaller secondary duct carried the same quantity of air as the main duct, the velocity in the secondary duct would increase instead, but only a portion of the air is siphoned with each duct take-off, so the air in the smaller duct slows down.

Question 78

A floor has a load of 80 pounds/sf. The simply supported beams that carry the floor span 40 ft and sit 16 ft on center. What is the maximum vertical shear in each beam? Use the reference tabs on your NCARB demonstration exam by clicking on MyNCARB, signing in, and selecting the ARE 5.0 demonstration exam from the right-hand column.

Answer 78

A: 26 kips

Linear load on beam:

80 psf * 16 ft = 1280 lbs/ft

1280 lbs/ft = 1.28 kips/ft

1.28 kips/ft = 0.107 kips/in

Length of beam:

40 ft = 480 in

Calculate the maximum shear:

V = wl/2 (from the references)

V = 0.107 kips/in * 480 in / 2

V = 26 kips

In structural calculations, we’d want to always round up, but because of individuals’ differences in rounding as you calculate, the exam will accept a range of numbers. In this case, perhaps any number between 25 and 27 would be accepted.

To watch an Amber Book : 40 Minutes of Competence video of me reviewing a similar problem, go here. For other 40 MoC YouTube videos, click here. To join the weekly group answering problems like this, email firms@amber-book.com.

Question 79

Why doesn’t this meet accessibility requirements?

Answer 79

Pilasters, columns, and other seemingly-insignificant intrusions into minimum clearance dimensions render room configurations out-of-code.

Question 80

In high wind areas with uplift risk–those in the path of hurricanes–codes require that wood-framed structures be structurally tied down, from roof to foundation. What hardware allows for this?

Answer 80

A: We can use tie-down straps, hurricane clips, or truss screws to hold down the roof structure to the wall structure

We can use J-bolts,cable or rod tie-downs, or expansion bolts, to tie down the wall structure to the concrete foundation.

Traditionally, we’ve sheathed wood-framed buildings with 8-feet tall OSB panels, but that requires two panels with a seam between. Taller (9-foot and 10-foot) OSB sheathing panels perform better than standard 8 feet tall panels because they allow continuous tension resistance by eliminating the need for a seam.

To prevent roof sheathing uplift, attach the panels with glue or ring shank nails (which have spiral ridges that give the nail 40% more holding power).

other helpful images can be seen here, here (scroll 1/4 of the way down the page) and here.

Question 81

An architect is renovating an old post office. An accessible route between the sidewalk and the entrance–33 inches above the sidewalk– is required.

What is the minimum length of an unobstructed straight ramp system required to create an accessible route between the sidewalk and entrance (including top, bottom, and intermediate landings)?

Answer 81

Answer: 48 feet long

Minimum 5 ft long landings on bottom, between ramp segments, and top

Maximum 1:12 slope

Maximum ramp segment length, before a landing is required, of 30 ft

Therefore maximum ramp segment rise, before a landing is required, of 30 inches

We need to get visitors up 33 inches. For the ramp, we need. . . .

5 ft long for the bottom landing

+ 30 ft long for maximum ramp segment length at steepest 1:12 slope allowable to rise the first 30 inches

+ 5 ft long for the intermediate landing

+3 ft long for maximum ramp segment length at steepest 1:12 slope allowable to rise the last 18 inches

+ 5ft long for the top landing. . .

5 + 30 + 5 + 3 +5 = 48 feet long, including bottom, top, and intermediate landings

Cumbersome ramps like this (48 feet long between sidewalk and entrance!) plague elevated buildings, renovated buildings, and buildings in localities with steep terrain. It seems a shame to require a second ramp segment, plus a five foot landing, just to elevate 3 inches past the 30-inch single-ramp cutoff, but I know of no other way, short of boosting up the sidewalk by three inches (not a bad idea).

Click here to re-watch an Amber Book course video that will demonstrate ramp length calculation.

Question 82

This painted CMU wall suffers from peeling paint. Why?

Answer 82

Answer: There is no airspace/drainage plane/capillary break behind the CMU. here is no airspace to drop down in, no flashing to direct outward, and no weep vents or weep holes to bring moisture to daylight. Therefore, on wet days, moisture moves into the wall, but it has no where to escape. On subsequent dry days the trapped moisture wicks back out through the CMU and loosens the paint from behind.

Question 83

How many layers of gypsum wall board are required on each face of a two-hour-rated partition?

Answer 83

A: 2 layers of Type X gypsum wall board on each side of the stud (typically)

Fire ratings: When in doubt assume. . . .

That a one-hour wall has one layer of 5/8” Type X gypsum wallboard on each side of a stud.

That a two-hour wall has two layers of 5/8” Type X gypsum wallboard on each side of a stud.

That a shaft wall (two-hour) has one super-thick layer (1”) Type X gypsum wallboard (called a “liner panel”) on one side and two 5/8” layers on the other side. That’s because laborers need to install the shaft drywall from the “wrong” side, for instance, on the fourth-floor level of a seven-story shaft. Installing two layers of gypsum board from the shaft-side would require a lot of scaffolding in a tight shaft space.

Question 84

Define:

Bending stress

Bending moment

Section modulus

Modulus of elasticity

Answer 84

Picture a fully-loaded beam

Bending stress: how much the bottom of the beam center wants to split apart

Bending moment: how much the beam wants to “smile” when loaded

Section modulus: how strong is the shape of the beam

Modulus of elasticity: how strong is the beam’s material (steel, wood, reinforced concrete)

Question 85

What happens to the bending stress if we triple the section modulus (while holding the maximum bending moment constant)?

Answer 85

A: The bending stress divides by 3. Those two terms–bending stress and section modulus–are inversely-related.

S = M/Fb

Section modulus = maximum bending moment/bending stress

or

strength of beam shape is the ratio of how much the beam wants to smile to how much the bottom of the beam’s midpoint wants to pull apart

Think about that relationship for a minute so you can recall it during the exam. That formula is given in the references tab, but not in a easy-to-understand-the-relationships way. . . so i recommend that you memorize this one.

Question 86

This photo was taken in December, 7:30am. It hadn’t rained recently and the temperature was 34 degrees. The wall is wet (dark pink); what causes the vertical dry lines (light pink) where the studs are? Explain in your own words.

Answer 86

Morning condensation (dew) forms on the whole wall. Then thermal bridging at the vertical studs (and horizontal top plate) dries out the wall locally to make the light pink lines. The attic is ventilated so inside the attic is also about 34 degrees, so no thermal bridging (and no stud-pattern drying) there, but maybe the attic is a bit warmer than the outside air because heat rises through the house to slightly heat the attic air. Convection from the warmer-than-outside attic air, and the drying nature of moving air, then causes the light pink dry spot around the attic vent too.

That’s my guess as to what’s happening. If you have a better one, email me at online@amber-book.com

Question 87

You already know that code requires GFI outlets in bathrooms, kitchens, and outdoors. Where else are GFI receptacles (or circuits) required (that is non-obvious)?

Answer 87

A: Crawl spaces, basements, garages, hot tubs, laundry areas

Question 88

You already knew that code requires GFI outlets in bathrooms, kitchens, and outdoors. Now you also know they’re required in crawl spaces, basements, and garages. Where are GFI receptacles (or circuits) NOT required (but you might think that they would be)?

Answer 88

Dishwashers and other non-counter kitchen appliances (protection is generally required only for counter applications)

Hot water heaters (not many people spend much time near them)

Attic (it seems like attics should require protection because other auxiliary spaces like crawlspaces do. . . but there’s not much risk of standing water in an attic, nor are there many people spending time in an attic.)

Question 89

Where CAN’T you locate an electrical panel?

Answer 89

Code requires three-feet clear (30 inches wide, six feet high) in front of a panel, so not in very small rooms. The clearance requirement may be bigger for higher voltages. Must be mounted below 6′-7″

Not near easily-ignitable content (i.e. clothes closets)

Not in (residential) bathrooms

Not over a stairway

Not in janitorial closets

Question 90

List the advantages and disadvantages of EIFS

Answer 90

Advantages:

Inexpensive: That’s why you see it on crappy shopping centers

Ornament easy to add (click here): Because EIFS is synthetic stucco over styrofoam, we can glue on ornamental styrofoam and just stucco over it.

High effective R-values: continuous exterior insulation eliminates thermal bridging

VERY flexible: doesn’t require control joints to prevent cracking and does well in earthquakes (EIFS still needs isolation joints when butted against another material or at a building isolation joint)

Disadvantages:

Doesn’t breathe: Moldy in wet climates, unless you ensure a drainage plane behind the styrofoam

Easily damaged: High-impact flavors are available, but even those aren’t that robust

Just generally not that durable for the reasons above, and hated by much of the public as cheap-looking, especially over time

Question 91

Look at this curtain wall detail. Identify each component’s function and figure out what supports what.

Answer 91

Curtain walls are delightfully complex. Break it down into systems. Identify on that same detail each of the following systems.

(1) Glass
(2) Spacers and silicone goo to seal the glass and attach it to a metal structural frame
(3) Structural attachments linking the building structure to the secondary structure of a curtain wall
(4) Aluminum covers to cover the ugly structural metal frame; these sections look comically complicated, but all those bumps and wiggles in the aluminum section allow pieces to snap in place without visible hardware
(5) More aesthetic cover pieces so we can’t see any of the gaps between building and curtain wall
(6) A continuous line of mineral wool firestop to keep fire from spreading behind the spandrel

Question 92

Where does roof flashing go? If you need help picturing a roof, click here.

Answer 92

See here.

You’ll need flashing anywhere water, flowing downhill, meets an obstacle: Vent pipes, chimney, skylight, and roof valley.

You’ll also need step flashing anywhere water, flowing downhill, runs alongside an obstacle: chimney, a section of the building that extends beyond the roof, etc. see here.

Question 93

Draw a window sill detail for a stick frame building with a masonry facade.

Answer 93

See here.

Break it down into systems.

Structure: the window needs to be in line with the studs

Thermal: the window needs to be in line with the insulation

Rain: all exterior horizontal surfaces should slope away from the window. Use sealant, flashing, and/or lapping to keep water from entering

Appearance: Cover up the ugly stuff with trim and blocking

For other examples, see here here and here.

Question 94

Draw a window head detail for a masonry building with a CMU structural wall.

Answer 94

See here.

Break it down into systems.

Structure: a lintel must support the masonry which can’t span the window opening on its own.

Structure: the window needs to be in line with the structural wall, but. . .

Thermal: the window needs to be in line with the insulation, which is outboard of the structural wall.

Rain: Drip edge so there’s no capillary action bringing water back to the window! All exterior horizontal surfaces should slope away from the window. Use sealant, flashing, and/or lapping to keep water from entering

Appearance: Cover up the ugly stuff with trim and blocking

For other examples, see here, here, and here.

Question 95

When do we require a. . .

Fire wall

Fire barrier

Fire partition

Answer 95

Fire wall: An independent structural wall that extends from foundation to (or through) roof. We use it to make one building into “two” buildings so that if fire causes a collapse on one side, the other side won’t collapse. We see these separating townhomes. Click here for an example. here too.

Fire barrier: Runs continuously from the structural deck below, through the dropped ceiling, to the structural deck above. We use it to protect our egress path and shafts from the rest of the building. Click here for an example. This is the one that the exam likes to test you on the most.

Fire partition: Also runs deck to deck–or stops at the ceiling, provided the ceiling is also fire rated. We use these to separate tenants in a building. Why do we care if the partition can stop at the ceiling? It allows us to run sprinkler pipes, other water pipes, ducts, and conduit above the ceiling from room to room without having to carefully penetrate a sealed deck-to-deck fire barrier. We can build a fire-resistant box-in-a-box room within a building. See here for an example.

Each of these will have flavors that are rated 1-hour, 2-hour, 3-hour, etc.

Question 96

What’s going on here?

Answer 96

Solar-assisted heat pump: on cold sunny days, the temperature of the solar-heated water in the tank is warmer than the air. The low-pressure evaporator snakes through that tank and can turn refrigerant liquid to gas more efficiently because the molecules want to dance when they are warmer. (the high-pressure condenser coil sits in the air-handling unit). The physics is similar to a geothermal system: in the same way that water underground is warmer than the wintertime air, water heated by the sun is warmer than the wintertime air. This is difficult. . . so if you understand it, know that you understand HVAC, and if you don’t understand it, go easy on yourself.

Question 97

What is a . . . .

ridge beam

jack rafter

valley rafter

hip rafter

rake

dormer

rafter tail

Answer 97

Go here

then go here

Question 98

Cavity wall masonry veneer with a concrete block backup wall: Use two-piece masonry ties or corrugated masonry ties?

Answer 98

A: two-piece masonry ties

Corrugated masonry ties are only allowed with wood stud backup walls (residential construction), and only then with a 1″ airspace between the stud wall and brick veneer wythe.

Most other configurations don’t allow corrugated masonry ties because they fail over time

Minimum cavity dimension of 1″ and maximum cavity dimension of 4.5″.

Deeper airspace than 4.5 inches (for lots of insulation)? That’s okay, but that triggers a performance code requirement (vs a prescriptive code at less than 4.5″): your structural engineer will have to prove that the ties you’re using are structurally up to the task for your specific weight of masonry veneer, seismic profile, etc.

Watch this excellent video on the subject (a must).

Then scroll through this excellent blog post on the subject (also a must).

So many clever ways to attach brick or stone to the block, steel, concrete, or. wood backup wall! Don’t memorize them, but be familiar with them and know the extreme limits of corrugated sheet metal.

Question 99

How do we prevent the brick or stone from crushing itself under its own considerable weight in mid-rise or high-rise masonry buildings?

Answer 99

Every few floors, we support the masonry veneer with continuous steel angle tied to the structural wall behind. Click here (and note the need for flashing and weeps to allow for water in the airspace cavity behind the masonry to escape)

Question 100

In a free field, every time we double the distance from a lighting source, the light level drops by _____.

Answer 100

A factor of 4.

Just knowing this “inverse-square” relationship can make a seemingly difficult problem much easier.

If you’ve moved the receiver from

one foot from the source

to 16 feet from the source,

remember that you’ve doubled one to two feet, doubled again to four feet, doubled a third time to eight feet, and a fourth time to 16 feet. . . . so if at one foot we measure 800 foot-candles, at two feet we’ll see 200 foot-candles, at four feet we’ll see 50 foot-candles, at eight feet we’ll see about 13 foot-candles, and at 16 feet we’ll see about three foot-candles from that fixture. Read that paragraph again if you didn’t get it the first time. It drops fast as we increase the distance.

The formula, in case you don’t have an easy twice-as-far scenario, is

So in our example

(In acoustics, every time we double the distance, the sound level drops by 6 decibels.)

Question 101

What is the required fire rating of a primary structural frame element (like a column) for a building of Type IIB construction? You’ll want to use this code excerpt to find the answer.

Answer 101

No fire rating necessary. You’ll need to know how to read tables 601 and 602 in the IBC

Question 102

> What is the required fire rating of a west-facing exterior wall for an office building of Type IB construction? On the west side, the nearest building is 40 feet away and the property line is 20 feet away. You’ll want to use this code excerpt to find the answer.

Answer 102

A: one-hour fire rating. Office buildings are Occupancy Group B. The fire separation distance is to the property line or, in the case of street-front properties, the middle of the street. . . not to the next building (since someday the adjacent property could theoretically have a new building right at the property line).

You’ll need to know how to read IBC tables 601 and 602 for these exams (not just PDD).

Question 103

What is happening here?

Answer 103

The “exit” –the fire stair– needs to be kept separate from the rest of the building so (1) smoke and fire won’t easily move up a floor through the stairway path and (2) occupants fleeing the building won’t have to breathe smoke and battle flames on their way down (we want people to be temporarily safe if they make it to the stairway entrance on their floor). Doors must be closed to separate the fire stair, but opening the door every time is often inconvenient and undesirable. So we developed electromagnetic door holders (also called “mag hold open” devices). When the fire alarm signals, the system cuts off the electromagnet at to the door holder and the door automatically closes, protecting the stair. Because the magnet holds it open, were the power to go out in a fire, the door would also close automatically.

We use similar fire-rated doors to separate different occupancy groups within a building or different buildings that we connect with indoor access hallways, and we can use similar door hardware there.

The design in the picture on the front is better than most. Note the custom niche that snuggly fits the door so it feels like there’s no threshold to access the stairs. This is a recent retrofit of a crappy office building, and it made a shockingly impactful visual and circulation improvement. More than I could have expected or hoped.

To see a good video on the subject, one that uses a battery for the hold-open instead of a hard-wired system, click here.

Question 104

Tell me what you can about the example in Red: What does it tell you?

Answer 104

A: Preliminary sizing of mechanical systems. In this case. . .

Question 105

Most of my examples, and most of what you’ll see in the world, and most of what you’ll see in the exams focus on uniformly loaded buildings. But you should also be familiar with point loads.

Answer 105

You don’t have to memorize the concentrated load formulas (they’re available to you during the exam). . . I just want you to understand how to find them, how to read the formulas, and when to use them.

How’d I find that? It’s on the NCARB demonstration exam. Go to https://my.ncarb.org/Home/ and sign in. The demonstration exam link is on the right-side column. Once you’ve launched the exam, click on “References” and then “Structural”

If the idea of manipulating structural formulas gives you hives, know that–while I personally think that you should understand these formulas to be a better professional–they represent a surprisingly small portion of the exams and you’re okay skipping them.

Question 106

What is the difference between ground fault interrupters (GFI) and arc fault circuit interrupters (AFCI)?

Answer 106

GFI switches the circuit off in the presence of water and GFI receptacles or circuits and code requires their use outdoors, laundry areas, garages, crawl spaces, basements, kitchen counters, and anywhere within 6 feet of water. They are not required for dishwashers, water heaters, or attics.

Arc fault interrupters switch the circuit off in the presence of static electricity from a billowing curtain, or from a nail from a picture-hanger hammered through a wall that accidentally strikes a hidden wire, or from furniture smooshed against a plug that damages the prongs. Code requires arc fault interrupters for circuits or at receptacles in residential construction (not required in unfinished basements or garages). For photo examples of common wiring conditions that arc fault circuit interrupters intend to protect you from, click here (after viewing it, you’ll want to pull your couch away from your wall a bit).

Both GFI and arc fault interrupters monitor the current in a circuit or at a receptacle and switch off in the presence of an unexpected electrical flow imbalance. GFI primarily protects against electrocution from water; arc fault primarily prevents fires from instances where wire damage puts the hot wire in contact with the neutral wire or ground wire and a resulting short-circuit heats up the wires.

Not for the exam, but for your practice (I don’t think that NCARB knows about this yet because volunteer architects create the questions and those questions get recycled every few years): Technology has given us receptacles with both arc fault and GFI protection, and those receptacles are typically what code officials in residences, on many walls. Someday soon the technology will be supple enough to detect either type of fault at the panel and we won’t have to do it at the individual receptacle level (GFI is currently available for an entire kichen/bathroom/garage/etc. circuit at the circuit breaker switch), but we don’t have arc fault with GFI whole-panel or circuit-wide detection yet. If you see it available, let me know at ermann@amber-book.com so that I can update this paragraph for those coming after you.

Question 107

How do we provide the capillary break (above ground) and hydrostatic pressure relief (below ground) for:

Roof?

Above-ground wall?

Foundation wall?

Foundation slab?

Answer 107

The idea behind a capillary break or hydrostatic pressure relief is that we redirect most of the rainwater or groundwater that would have otherwise made contact with the water control layer in the assembly–before the water even gets to that layer. This way, the water control layer has less water to control.

Roof: No true capillary break will be provided for a roof because we couldn’t really provide a proper capillary break, even if we tried. If we included a mechanically redirecting layer above the waterproof layer on a roof, and some water got past that first mechanical deflection layer, gravity would pull it toward the waterproof layer anyway. So in a roof, the top layer is usually the rain control layer and there’s no room for error. Unlike the above-ground wall, the foundation wall, or the foundation slab, we expect water to get in after 20 or 30 years as the exterior waterproof layer (shingles or membrane) degrades by freeze-thaw and sunlight UV. We actually plan for a new roof every few decades. . . can you imagine if we needed to do the same for the walls or foundation?. In low-sloped roofs, the slope and drains remove the water to gutters, rain gardens, cisterns, or municipal drains. In sloped roofs, lapped shingles mechanically direct rain to a gutter and any rainwater that gets through the shingles may meet an optional peel-and-stick backup membrane. Or it may meet an attic ventilated to gradually dry out the moisture from tiny leaks. In the image below you can see the peel-and-stick rain control layer waterproof membrane before shingles were added above it. (I suppose you could call the space between the shingles and membrane a capillary break, but not really because gravity pulls water that gets past the shingles to the membrane anyway). In this image, you can also see the wall’s fluid-applied waterproof layer. Portions of it will be covered by masonry, portions by metal panel rain screen, and portions (already installed) by precast concrete. Note that the roof membrane laps the wall’s fluid-applied water control layer so that any roof water not directed to the gutters, can’t sneak behind the wall rain control layer.

Above-ground wall: We’ll use an air gap capillary break, with a network of weeps and flashing to direct water from the air gap to the weeps. When rainwater sneaks past the mechanically deflecting layer (in the image above, the mechanically deflecting layer will be the (installed) precast concrete, the (not-yet-installed) stone, and the (not-yet-installed) metal panels). We need to think of keeping a wall dry as a system (rather than a product). See the capillary break air gap and the flashing that redirects water in the diagram below.

Not all (and maybe not most) walls include a capillary break. For instance, the siding on a house typically sits flush to the rain control layer behind it; but buildings scientists tell us that the assembly will perform better with furring strips and a capillary break (see here for an excellent video). Most non-residential buildings will include a capillary break.

Nor are all effective rainwater control layers watertight! They simply need to be able to shed rain that sneaks behind the mechanically-deflecting layer, so lapped building felt (tar paper) or lapped polymeric building wrap (Tyvek) can also work well as an air-permeable (tar paper) and vapor-permeable (both tar paper and Tyvek) rain control layer. In the lapped (but not taped) example, you’ll then need to provide an air control layer at some other plane in the assembly.

Foundation wall: We’ll want to damp-proof (lower bar) or waterproof (higher bar) the foundation wall with fluid-applied goo or peel-and-stick membrane. But we’d prefer that our water control layer benefit from some system to reduce the water pressing against it. The ground is always wet. After a rain, hydrostatic pressure will push that excess subsurface water against a foundation wall if we don’t send it elsewhere. Provide the capillary break hydrostatic pressure relief by redirecting water that would have otherwise pushed against the foundation wall down with dimpled drainage board (geotextile held slightly off a plastic sheet to keep soil out and allow water in) to a foundation perforated pipe “French drain.” In times of excess subsurface water, the perforated pipe partially fills and water is directed down to daylight (for a sloped site) or to a sump pump (for a flat site). In the image below you can see the waterproof peel-and-stick membrane.

Then we apply the dimpled drainage mat

The drainage board directs water to a perforated pipe French drain that fills with water when excess is present.

And then the water in the French drain perforated pipe is directed to daylight or a sump pump

Foundation slab: Again, we’d like to protect the enclosure, just outboard of the enclosure, with a waterproof layer, so we’ll install a plastic sheet (polyethylene, yellow in this case) right below the slab before pouring it like this.

But we’d prefer to relieve the hydrostatic pressure of saturated soil pushing water against that sub-slab plastic layer. . . so below the plastic (and optional insulation) we’ll find gravel pieces of similar size (“well sorted” or “poorly graded”). Subsurface water can then partially fill the reservoir made by the gaps between the 3+ inches deep gravel layer and keep the hydrostatic pressure off the plastic and out of our basement floor. Unlike the roof, above-ground walls, and subsurface foundation walls, we don’t typically drain the water underneath a slab and rely instead on this “reservoir” system.

Question 108

Advantages and disadvantages of rectangular duct section vs spiral duct section?

Answer 108

Spiral only comes in circular sections, so if floor-to-floor height is tight, and you’d like to make a higher dropped ceiling, you’ll want to use rectangular duct so you can made a thinner profile in the duct height and a longer one in the duct length for the same cross-sectional area. For instance, an 18″ spiral round duct can carry the same amount of air (because it has the same cross-sectional area) as a 41×11 rectangular duct. . . so the spiral round duct will require 18″ of clearvheight above the dropped ceiling, and the rectangular duct, by comparison requires only 11 inches.

Sprial duct is a bit less expensive (less sheet metal and happens to come. in longer lengths, so less in-the-field joining.

Spiral duct is easier to seal tighter, offers less friction to the air for more efficiency and therefore a quieter fan because the fan doesn’t have to work as hard.

Rectangular duct, however, has a “drum effect” as the flat sides move back and forth like a drum absorbing sound energy, so rectangular duct, though increasing fan noise, attenuates much more of the fan’s sound, per linear foot of ductwork, making for (possibly) a quieter result with long duct lengths.

Branch take-offs, where a smaller duct branches off a larger trunk line, are (slightly) more difficult to construct in circular ducts than in rectangular ducts because of the simpler side wall geometry of rectangular ducts.

Question 109

An architect is tasked with rehabilitating a century-old post office into a modern train station. The drawing below is the floor plan, as measured in the existing building. What does the “+/-” on the right-hand dimension line mean?

Answer 109

A: It tells the contractor where the tolerances are.

See the video explanation below.

http://flashcards.amber-book.com/wp-content/uploads/2021/07/PDD-114-Tollerances-in-measurement-answer-video-LOW-RES.mp4?_=1

Question 110

A large chandelier will be supported by a beam but can’t be attached below the neutral axis. The beam is made of ______.

Answer 110

A: Timber. . . wood (heavy timber, dimensional lumber, or CLT)

In a beam, the top sliver–above the neutral axis–is the part that sits in compression and the bottom sliver–below the neutral axis–remains in tension. In some point load cases, screwing into the bottom of the beam risks splitting the bottom of the beam.

Question 111

Which one fails, the aluminum roof or the copper clips that attach it?

Answer 111

With galvanic action, one metal corrodes the other.

The aluminum or zinc corrodes when in contact with brass or copper. See here.

Question 112

Which is less expensive to install: aluminum or copper?

Answer 112

A: It depends. Aluminum’s advantage is that it weighs less (cheaper to install for large buildings); copper’s advantage is that it’s smaller for the same current capacity (cheaper to install for small buildings).

Copper is almost always used in residential branch circuits because it requires less skill for homeowners to safely work with. If exposed aluminum wire isn’t immediately treated, it will develop an oxide film that may heat up later and seed a house fire.

Of course, the prices of copper and aluminum, as all metal commodities, fluctuate wildly, so at any given time, external market factors may push a finger on the scale to make one less expensive than the other. Click here to see what happened to two prices in 2006.

Question 113

What are busway, busduct, and cableduct, and when are they used?

Answer 113

Busway looks like this. It replaces wire in conduit for large installations and includes copper or aluminum conductor bars housed in a protective metal casing. Its section detail looks like this. Economically, busway provides an advantage when the following two conditions are met:

(1) We want to carry large amounts of current (up to 4,000 amps. . . to put that in perspective, your bedroom circuit probably can handle 10 or 20 amps). So we’ll run busway from the basement of a tall building to the elevator machine room on the roof or from an electrical room to the watt-hungry robots on our factory floor.
(2) We want to tap into the busway at frequent intervals along its length. So we’ll tap into that same busway to provide power to each floor or each robot.

Busways replace a single, large-diameter, wire because as diameter increases, the conductor becomes less efficient. The flat bars inside a busway can carry more power with less resistance and are less likely to heat up than a thick wire or bunches of thin wire. Further, tapping into a big wire or collection of wires at each story (or at each robot) requires significant labor to manually create conduit takeoffs.

Plugin busways allow for easy connections (and later, disconnections). See this data center.

“Busduct” is simply another word for busway.

Cableduct (also called cablebus) looks like this and is just what you think: rigidly mounted insulated cable (instead of bars) running inside the same type of protective metal duct housing. The duct for cable duct is ventilated because cables running in free air can carry more current than cables stuffed into conduit. Relative to busbar/busduct, cableduct is more rare because of its bulkiness and difficulty with tap-offs.

To watch an Amber Book : 40 Minutes of Competence video on the subject, click here.

Question 114

Assuming that the ducts are obscured behind a dropped ceiling, how much room above the ceiling is required to run the HVAC ducts in the large main room inthis drawing?

Answer 114

A: 14″ (plus the depth of hardware to hang the duct, plus any extra depth needed for sprinkler pipes crossing below ducts, plus the depth of light fixtures if they fall directly underneath ducts in plan, etc.)

A duct labeled 11X14 indicates a duct 11 inches wide and 14 inches tall.

A duct labeled 32X14 indicates a duct 32 inches wide and 14 inches tall.

Question 115

What does the “885CFM”in this drawing tell you?

Answer 115

There are 885 cubic feet per minute intended to flow through that portion of duct.

If you can’t picture a duct damper, click here to see what they look like. Often a duct system is riddled with dampers used to open up (or choke off) the duct to more (or less) air. After installation of the mechanical system and before the owners take occupancy of the building, a team will “test and balance” the ducts, closing and opening dampers to get as close as reasonable to the intended CFM rates on the drawings. This process resembles “Whack-a-Mole” because as soon as you adjust one damper, the airflow in the ducts that you already balanced changes and you have to go back and re-adjust each of those again, getting closer to the target CFM values with each pass.

Curious how the testing and balancing folks know how much air is coming out of a particular register or diffuser? They use a flow hood that looks like this.

Question 116

What does this symbol mean?

Answer 116

10-inch diameter round duct connecting another duct to a diffuser

Question 117

Which type of insulation attracts termites?

Answer 117

Any of the rigid foam insulations attract termites (extruded polystyrene, expanded polystyrene, and spray foam). Polyisocyanurate and open cell spray foam also provide a theoretical home for termites, but those doesn’t do well underground because of moisture sensitivity, so these two typically wouldn’t be in play in a termite discussion. Some spray foams even use sugar as a flame retardant!

The good news: chemical treatment for termites around the foundation is very effective at keeping them out, even if you have rigid insulation underground.

Question 118

When do we use glycol in a cooling system?

Answer 118

1. We mix a bit of gylcol with water as an antifreeze, so that we can transport chilled water at lower temperatures and still keep the mixture flowing (and not becoming ice)
2. This is especially common in specialized industrial processes where we may need something to be VERY cold as part of the manufacturing: brewing, milk, pharmaceuticals, cosmetics, chemicals, etc.

Question 119

What are stepped or sloped footings for? See here so you know what they look like.

Answer 119

Stepped and sloped footings address the risk of punching shear. What is punching shear? The weight of a too-high concentrated load from the column wants to “punch through” the footing. See here for an example.

The stepped or sloped footings gradually spread the load out over a greater area of the footing.

If you still don’t own the concept of punching shear, be sure to look at this image depicting punching shear where a column meets a spanning floor slab. I promise you’ll own the concept if you click.

Question 120

Where do you locate overflow scuppers?

Answer 120

Code requires one overflow scupper for each (potentially clogged) roof drain, located in plan as near as possible to the roof drain it is responsible for backing up. I’d memorize that. See what I mean here. In practice, the bottom sill of a parapet scupper typically sits two inches above the roof’s surface, ensuring not more than two inches of ponding water if the drains clog.

Scuppers must measure at least 4 inches high and have a minimum width equal to the required circumference of the roof drain they are backing up. Code mandates a minimum roof drain size based on the amount of rainwater the drain’s catchment area can be expected to see in a storm event. You’ve calculated (and you will again calculate) this in other parts of the course, looking at code rainfall maps, determining a near-worst-case volume of water falling per hour on the horizontal projection of a catchment area, converting that volume of water from cubic feet to gallons and from per-hour to per-minute. . . and finally, selecting a roof drain, gutter, or downspout size from a table that rates drainage system component sizes in gallons-per-minute flow capacities. There are sometimes fewer steps to determining drain size, so be alert to what units are used for the drain size table. There are also different tables for horizontal gutters, vertical downspouts (both on the roof’s perimeter), and roof drains (somewhere in the middle of the roof’s surface).

There are two types of scuppers: (1) scuppers part of the primary drainage system, useful after an everyday rain event to carry the water off the roof and (2) scuppers part of the secondary drainage system used as emergency “release valves.” The second kind in this test item are holes in the roof parapet to prevent dangerous ponding on the roof that might overload the structure should the primary drainage system fail. You can see each kind, adjacent to one another, on this wall. If you see water coming out of an overflow scupper, you may have an urgent invisible problem (clogged drains and heavy ponding water that might collapse a roof)! This flashcard question asked about the secondary drainage/overflow kind of scupper, so we can assume it will be useful only if the primary roof drains fail. For a low-sloped roof, the primary roof drainage may be either a scupper with downspout or a roof drain, and the overflow roof drainage may also be either a slightly-higher scupper with downspout or a slightly higher roof drain

Question 121

Warm heating air rises to the top of a tall room in the winter. But the people who need the heat are standing on the floor. What to do?

Answer 121

Install a fan in the ceiling to mix the air.

Most ceiling fans have a bi-directional switch: blow downward in the summer when moving air helps cool occupants, and draw air upwards to generally mix the room air without blowing on occupants in the winter.

Stratification is a big problem in high-ceilinged rooms, especially if there’s a mezzanine. Do we make it comfortable for those on the main floor but too hot for those on the mezzanine? Or do we make it comfortable for those on the mezzanine, but cold for those on the main floor.

Plus, if the hot air in the room hovers near the ceiling, that’s an inefficient way to heat, perhaps wasting about 20% of the room conditioning energy.

Note the ceiling fans on the top of this large atrium.

Question 122

An owner, interested in low-cost, low-maintenance, and high-durability hires an architect to design a multifamily building. Which is a better choice for the kitchen cabinet finishes, Acrylic or PVC?

Answer 122

A: PVC

Factories make modular kitchen cabinets by laminating layers of resins and papers under high pressures and temperatures. PVC offers a lower cost, lower maintenance, and higher durability. Then who would specify acrylic? Acrylic offers a glossier finish than PVC, so if glossy is the design goal, acrylic may be a better option.

Curious about the difference in look between the two options? Click here

Question 123

How are ducts supported from the ceiling structure?

Answer 123

Like this. Or from straps like this. Or from trapeze hangers like this.

Question 124

When are parapet railings required on a roof?

Answer 124

When the roof includes–within 10 feet of a roof edge–mechanical equipment, hatches, or other equipment requiring regular servicing, code requires a 42-inch-high fall protection guard.

Provided that the parapet extends up to that 42-inch height above the roof surface, the parapet itself can double as the fall protection. Many parapets that predate this 2010s-era safety requirement happen to fall just-short of the 42″ height minimum. Argh. Grandfathered roofs get a pass until a major renovation triggers an update to comply.

The renovation typically means losing grandfathered status and adding a railing, either attached to the parapet mechanically, or if that’s not possible for structural reasons, we’ve developed railing systems that do not penetrate the existing structure and use weighted bases instead. Typically the railings lean inward in section, away from the roof edge, both because that configuration is stronger, and because it’s less visible from below.

Some code officials will let slide, for example, a roof-mounted exhaust fan outlet within 10 feet of the perimeter, provided the exhaust equipment on the roof is only the exhaust grille (no moving parts that will need to be serviced). . . but if the motor up there may need maintenance one day, or if there’s a filter that needs to be changed regularly, you’ll need to provide the railing.

For a new building, which solution is less expensive, parapet or railing? It depends: if the parapet was going to be 38 inches high ANYWAY, adding a few more inches may be a no-brainer. . . but otherwise, the railing system is less expensive by a lot. Of course, you MAY be able to get away with no fall protection if no equipment or walkways are near the edge (obviously you’ll need to check the code): one more reason to not outsource locating roof-mounted mechanical equipment fully to the mechanical engineers.

Question 125

How do you prevent residential windows from leaking?

Answer 125

For the answer, watch this window review Amber Book : 40 Minutes of Competence with guest Christine Williamson, creator of Building Science Fight Club (follow her on Instagram if you are not already doing so). Watching this is optional for your studying, but super-worthwhile for your career.

Question 126

What is a lag screw? A lag bolt?

Answer 126

Lag screws use hexhead or sqaure-head screwdrivers. They look like this and require tool heads like this or this.

Lag bolts taper and are threaded like a wood screw and therefore don’t need washers or nuts. They look like this. A wrench drives them.

Question 127

What is bentonite used for?

Answer 127

Bentonite is a type of self-healing, expanding, durable clay. In construction, we use it for. . .

Waterproofing: as the active ingredient in self-healing sheets that resist future puncture applied to foundation walls or injected in a milkshake consistency against a leaky basement wall.

Injected as a grout into geothermal wells to maintain contact between the underground tubing circulating water and the earth that will exchange heat with the water in the tubes. See it poured into a geothermal well here.

Question 128

Does duct lining quiet a duct?

Answer 128

Internal duct lining quiets fan noise moving through ductwork a LOT (but has air quality concerns from (1) mold growing in the fibrous dark liner and (2) particulates from the fibrous lining fibers blowing loose and swirling around the room and in your lungs)

External duct lining fails to quiet a duct

Flexible duct: If the last 3 to 12 feet of a duct run is swapped for flexible duct (which also allows tolerance for diffuser placement) it will quiet AC noise. The research suggests flexduct makes the room moderately quieter. . . but my experience tells me it often makes the room much much quieter.

Question 129

Why use a flitch beam?

Answer 129

A flitch beam sandwiches a steel plate between two timber beams and bolts the whole assembly together. They look like this.

We used to use them because they offer more strength, longer span, shallower beam depth, and increased dimensional stability than timber-only beams.

We use flitch beams less than we used to (outside of historic renovation) because they’ve been partially supplanted by less expensive engineered wood alternatives (like glulams).

Question 130

How does geothermal (energy production) differ from geothermal (heating and cooling)

Answer 130

The two couldn’t be more different and it’s a pity that they have the same name.

Geothermal energy production: brine-water solution in natural magma-heated hot-water springs is pumped up to the surface to spin a turbine which generates electricity at the utility (rather than at the building) scale. Carbon-free and renewable, but obviously available only in places with active hot water springs. Provides fully 6% of California’s energy production and promises future growth.

Geothermal heating and cooling: water solution is pumped from the evaporator (or condenser) underground and back again to make an AC system much more efficient because soil underground is warmer than the air in the winter and soil underground is colder than the air in the summer. This doesn’t work in extreme climates because. . . .

If the climate is always hot, the building will be cooling (almost) all year, continually depositing the building’s heat into the ground, heating up the ground over time, and eliminating the advantage of using the ground to temper the hot air.

Likewise, If the climate is always cold, the building will be heating (almost) all year, continually depositing the building’s coolth into the ground, cooling down the soil over time, and eliminating the advantage of using the ground to temper the cold air.

It seems crazy to me that our AC system can quasi-permanently change the temperature of the soil!

So geothermal AC systems work best when the heating load and cooling load of a building are nearly equal.

*To avoid this confusion, for decades, building scientists attempted to refer to geothermal heating/cooling by one of its more-correct names: “geo-exchange” or “ground-source-coupled heat pumps”. . . but those names never stuck and most of us gave up. The confusion has persisted. I can’t find it online now to share it with you, but in the 2000s I read a Metropolis Magazine article about geothermal heating/cooling. . . only the graphic accompanying the article was a US map of magma temperatures!