Basement

Question 1

What is the purpose of ‘Footings’?

Answer 1

To receive loads through posts or foundations walls to transmit them to the soil.

Question 2

What is important to consider for footing sizing?

Answer 2

• A soil test must be done beforehand.
• Sizing is done by a structural engineer.
• Must be below the frostline.

Question 3

A footing is made up of what material?

Answer 3

Poured concrete or wood.

Question 4

Here are some things to consider for ‘Footings’

Answer 4

-Undisturbed soil, rock, compacted granular fill ( When soil is taken out, properties of soils are now different )
- Drainage
- Insulation
- Key or re-bar to resist lateral pressure, bonds footing to foundation wall

Question 5

Define ICF

Answer 5

Insulated Concrete Formwork

Question 6

True or False. Foundations supports building loads including snow and occupant loads.

Answer 6

True.

Question 7

Name a few materials used for formwork.

Answer 7

• Steel
• Plywood
• Plastic sheets

Question 8

What are anchor bolts used for?

Answer 8

To hold sill plates in place. ( 1/2” dia. max 8’ apart; embedded minimum 4” in concrete; bent to provide maximum bond )

Question 9

What do we used to reinforce concrete foundations?

Answer 9

10mm bars @ 600mm made of steel, glass or plastic fibres.

Question 10

What are some components of ICF?

Answer 10

• Replaces conventional systems
• Made of polystyrene
• Proprietary systems, plastic clips hold rebar in place
• Ultra efficient
• Expensive but payback period is short
• Must add a membrane on the exterior

Question 11

Describe Basement Slabs.

Answer 11

• Generally 4” thick
• Sloped towards drain
• Reinforcing mesh
• Typically to prepare for the basement slab, 4” ( 100mm ) minimum of 3/4” ( 19mm ) crushed stone is compacted over the subsoil as a drainage layer to keep water away from the underside of the slab.
• Put coarse gravel and a polyethylene vapour diffusion retarder under a concrete slab to keep water vapour and water in the ground from getting into the slab from underneath.
• Pyrite

Question 12

Describe ‘Foundation Wall Drainage’

Answer 12

• Foundation drainage normally consists of a drain tile installed around the perimeter of the basement and a wall drainage layer ( also known as a drainage mat )
• The perforated drain tile is usually 4” in diameter and is laid at the level of the bottom of the footing. The tile is wrapped with a geotextile fabric to keep out of the fine soil particles.
• The tile is then covered with min. 6” (150mm) clean gravel or crushed stone.
• This tile is then connected to basement sump pump.

Question 13

Describe Radon and Soil Gases

Answer 13

• Radon is caused by the decomposition of soils that contain uranium
• Radon is radioactive, colourless and tasteless, and can cause lung cancer
• Keeping soil gas ( radon, water vapour, herbicides, termiticides, methane, etc. )
• Soil gas moves due to pressure differences
• Since we cannot eliminate the holes, the best thing we can do is control the pressure.
• The granular fill located below the concrete slab can be integrated into a sub-slab ventilation system to control soil gas migration by creating a zone of negative pressure under the slab.
• A vent pipe connects the gravel layer to the exterior through the roof.

Question 14

Define WWF

Answer 14

Wielded Wired Mesh

Question 15

Name the 4 sources of moisture.

Answer 15

• Rainwater draining from a roof
• Rainwater entering the ground
• Natural springs in the ground
• Ground water table

Question 16

Describe what is ‘Water Vapour’

Answer 16

• Water vapour flows from warm to cold
• Water vapour dries through a process called evaporation
  Definition: Particles of liquid moving from an area of higher concentration to one of lower concentration.

Question 17

Describe basements, water managed foundations.

Answer 17

• Keep rainwater away from the foundation wall perimeter.
• Drain groundwater with sub-grade perimeter footing drains before it gets to the foundation wall.

Question 18

What is Iron Ochre?

Answer 18

Iron ochre is a bacteria present in soils that are generally sandy and rich in oxygen. The bacterium appears as a slimy paste that clogs drains and prevents them from functioning properly. ( due to geotextile membrane )

Question 19

Waterproofing vs Dampproofing

Answer 19

• Waterproofing relies on creating a watertight barrier without holes
• Waterproofing seeks to prevent the passage of water through the basement wall by the application of a waterproof membrane.
• Damproofing protects foundation materials from absorbing ground moisture by capillarity.
• Dampproofing is not intended to resist groundwater forces ( hydrostatic pressure )
• If water management is used, waterproofing is not necessary
• However, control of capillary water is still required ( dampproofing )
• Dampproofing is typically provided by coating the exterior of a concrete foundation wall with a bituminous paint or coating
• This coating is usually spray-applied or applied with a brush.
• A waterproof membrane could be applied to foundations in situations where drainage and dampproofing cannot provide sufficient protection such as in areas with high water tables.
• The most commonly used are liquid-applied membranes or peel-and-stick sheet membranes.

Question 20

Describe a Drainage Mat.

Answer 20

A drainage mat is a manufactured product made of a loose mat of stiff, inert fibres, a plastic egg-crate structure or some other very open porous material. It is faced on the outside with a filter fabric that prevents fine soil particles from entering and clogging the drainage passages in the mat.

• Any subsoil water that approaches the wall falls through the porous material of the mat to the drain pipe at the footing.

Question 21

Describe ‘Foundation Insulation’

Answer 21

• Minimum 600mm below grade, inside or outside
• Insulation on the outside reduces the temperature swing that the foundation wall experiences which often reduces thermal stresses and cracking that results.