1. Final Project - Building Envelope

Question 1

What properties of a material intended to be exposed to the weather or used in a humid environment should be considered? (2)

Answer 1

1. Water resistance
2. Water vapor resistance.

Question 2

What properties of a material that will be used in the construction of the outer envelope should be considered? (2)

Answer 2

1. Conductivity
2. Thermal resistance

Question 3

What properties of a material that will be used to finish the surfaces of a room should be considered? (3)

Answer 3

1. Transmission capacity…
2. Reflection capacity…
3. Absorptive capacity…

… visible light and radiant heat

Question 4

Name the 4 factors on which the evaluation of building materials must be based.

Answer 4

1. functional
2. economical
3. aesthetic
4. environmental consequences of their use (life cycle estimation)

Question 5

What properties determine the durability and maintenance costs of a material?

Answer 5

• The density or hardness of a material determines its resistance to wear and abrasion; the durability of this material and the costs of its maintenance depend on it.

Question 6

3 broad aspects which impact window performance

Answer 6

• Physical characteristics of window assembly (window as system of elements)
• Physical interference with the enclosure (component of build. envelope)
• Effects of windows on quality of indoor space (part of indoor environment)

Question 7

Function of cap bead & heel bead. What do these components prevent?

Answer 7

Cap: keeps rain out

Heel: air tightness (inside joint seal) * prevents air leakage

Question 8

3 Ways to mitigate condensation on windows.

Answer 8

• Add air space with plastic or glass
• Circulate warm air towards glass
• Remove obstructions

Question 9

4 Ways to mitigate sound transmission in a window system

Answer 9

• Large glazing caps
• Thicker glass
• Separate frames / sashes (int / ext)
• Completely airtight (fixed often perform better than operable)

Question 10

Functions of films & coatings on windows

Answer 10

• reflect solar heat back out
• reflect radiant heat back in
• reduce transmission of UV rays

Question 11

What type of window frame is best for high rise & commercial & why?

Answer 11

Aluminium

they can be designed to meet specific structural requirements

Question 12

3 Types of strengthened glass - pros & cons

Answer 12

1 - FULLY TEMPERED (surface in compression & core in tension)

+ 3-5x more resistant to fail due to bend, impact, heat

• impact along edge will shatter sheet

2 - HEAT STRENGTHENED (lower level of surface compression compared to fully tempered, same process)

+ stronger than annealed glass & less susceptible to shatter due to edge impact

3 - LAMINATED (bonded together with intermediate layers of plastic)

+ holds together if broken

+ can be used for solar heat control, sound control, bullet-resistance, blast resistance

• not stronger than regular annealed glass

Question 13

2 pros / 3 cons of PVC windows

Answer 13

+ low maintenance

+ stable in saline / polluted air

• steel in sash / frame for stability = increased thermal conductivity
• risk of cohesive failure at the joint
• limited light tones because of fading, expansion due to direct sun

Question 14

1 pros / 2 cons of unsealed windows

Answer 14

+ no need to be replaced due to condensation

• cannot accommodate any films, coatings, gases
• separate sash option typically only available in sliding windows

Question 15

3 pros / 2 cons of sealed windows

Answer 15

+ 2 surfaces to clean rather than 4

+ no condensation between the glass

+ability to incorporate films, coatings, gases

• metal spacer = thermal bridge (can cause condensation along cold perimeter of glass)
• deflection due to change in temp. & wind pressure = compression and tension cycle on sealant (can cause failure)

Question 16

As a point of reference, know the typical R value of single and double glazing (w 5mm air space).

Answer 16

single R = .88

double R = 1.61 *Approx

Question 17

List the 5 main forces of moisture transfer in a building envelope.

Answer 17

1. KINETIC ENERGY OF RAIN (impact)
2. SURFACE TENSION (drip edges)
   
   • water clings to horizontal(ish) surfaces
3. CAPILLARY (gaps <5mm)
   
   • water drawn into permeable materials & small openings (cracks, joints & junctions)
4. GRAVITY
   
   • moves rain down surface and into sloped openings (holes cracks flashing)
5. AIR PRESSURE DIFFERENCE
   
   • rain driven in direction of lower pressure

Question 18

What are the 4 ‘D’s of preventing rain pentration?

Answer 18

1. deflection
2. drainage
3. drying
4. durability

Question 19

List & describe the 4 main strategies for preventing moisture infiltration.

Answer 19

1. Integral Sills & Drip Edges on Flashings
   
   • typ. projection of 10mm beyond cladding
   • 25mm may be rqrd
2. Drainage Holes in Permanent Cladding
   
   • needs to slowly dissipate/evap water
   • min. 10mm to prevent capillary bridging
3. Sealants/ Gaskets reduce openings
4. Joints:
   
   1. Locked Joints (open)
      
      • ​​manage gravity driven
      • rqr 10mm overlap
   2. Lapped Joints (closed)
      
      • ​​rqr 5mm gap btwn to prevent capillary action

Question 20

Describe the 2 lines of defence in a rainscreen system.

Answer 20

1. CLADDING
2. a DRAINED CAVITY
   
   • intercept all water that passes cladding
   • dissipate water to exterior:
     
     • _​evaporation
     • drain via flashing

2.b or WATERPROOF MEMBRANE

Question 21

A rainscreen should also be protected, what are 3 ways to do so?

Answer 21

1. ROOF OVERHANGS
2. CORNICES
3. BALCONIES

Question 22

What is the primary purpose of thermal insulation?

Answer 22

Control the flow of heat through an exterior assembly.

Question 23

List the 4 most common types of insulation and their r-value per inch of thickness

Answer 23

Batt = 3.3 (same fiberglass or rock wool)

Rigid board

= 2.5 (cellular glass)

= 3.6 - 7.2 (the various polys - polyisocyanurate highest)

Foamed in Place

= 6.2 (polyuerethane)

Loose fill

= 2.1 -3.7 (vermiculite to cellulose)

Question 24

The steady state method of measuring thermal resistance of a construction assembly is useful,

but these 4 factor also influence heat/loss gain:

Answer 24

1. Surface colour / reflectivity
2. Mass (time lag)
3. Orientation (solar /wind)
4. Latent Heat (occ. etc)

Question 25

Masonry elements that are bonded together with mortar are stronger in ________________ than wood. A) shear B) compression C) shrinkage D) bending E) tension

Answer 25

B) compression

Question 26

What are the nominal brick sizes for: 1 - modular 2 - norman 3 - utility

Answer 26

1 - modular 100 x 68 x 205 (3.937"x2.677"x8.071") 2 - norman 100 x 68 x 305 (3.937"x2.677"x12") 3 - utility 100 x 100 x 305 (3.937"x3.937"x12") ## Footnote \*\*nominal brick sizing includes mortar joints

Question 27

What are these 3 types of face brick: 1 - FBX 2 - FBS 3 - FBA

Answer 27

1 - FBX = perfect/high degree of uniformity 2 - FBS = wider range of acceptable colour 3 - FBA = desired non-uniformity

Question 28

What is **efflorescence**?

Answer 28

Powdery deposit on face of brick, due to leaching and **crystallization of soluble salts** within material Best defence: _reduce moisture absorption_

Question 29

List and describe the 6 main varieties of brick. (example: soft mud)

Answer 29

1 - **SOFT MUD** • form brick w wet clay (20-30% moist) 2 - **SANDSTRUCK** (matt texture) • form w form lined w sand to prevent sticking 3 - **WATERSTRUCK** (smooth dense surface) •form lubricated w water 4 - **STIFF MUD** • extruding stiff but plastic clay (12-15% moist) 5 - **DRY PRESS** (sharp edge smooth surface) • form relatively dry clay (5-7% moist)

Question 30

What are brick grades a measure of?

Answer 30

Brick grades measure **durability when exposed to weathering**. According to: • compressive strength • max H20 absorb • max saturation coefficient

Question 31

What do the 3 brick grades below indicate: 1 - SW 2 - MW 3 - NW

Answer 31

These grades indicate **suitable weather regions** 1 - SW = Severe Weather (min. comp. str. 2500psi) 2 - MW = Moderate Weather (min. comp. str. 2200psi) 3 - NW = Negligible Weather (min. comp. str. 1250psi)

Question 32

In order of highest strength to lowest, list the 3 types of concrete used in concrete masonry units.

Answer 32

- Normal - Medium - Lightweight

Question 33

What do CMU grades indicate?

Answer 33

Suitability for load bearing: N = Loadbearing below and above grade S = Loadbearing above grade only

Question 34

How can you identify if CMUs have been manufactured to have a certain moist. content to prevent shrinking & cracking?

Answer 34

Type 1 = manufacture to have certain moist content Type 2 = not manuf. to have cert. moist. content

Question 35

What is the nominal size of a typical CMU block?

Answer 35

8 x 8 x 16" | (205 x 205 x 405mm)