Foundations as Building Enclosure

Question 1

Why do foundations require waterproofing and drainage? (3)

Answer 1

• where the building substructure encloses a basement, parking garage, or other usable space, groundwater must be kept out
• concrete alone is typically not adequate
• two basic approaches are used to resist water entry - drainage and waterproofing

Question 2

Describe the drainage process.

Answer 2

drainage mat and free-draining backfill material allow ground water to flow downward where it is collected by drain piping

Question 3

What role does drain piping play in the drainage process?

Answer 3

perforated piping conducts water away from the substructure

Question 4

How do filter fabric “socks” assist the drain piping?

Answer 4

filter fabric “socks” cover the piping to prevent soil particles from accumulating in and eventually clogging the pipes

Question 5

What is damp-proofing?

Answer 5

a moisture-resistant layer used where groundwater conditions are mild or waterproofing is not critical

Question 6

What is waterproofing?

Answer 6

prevents passage of water in more demanding conditions, even under hydrostatic pressure

Question 7

What are the two primary types of waterproofing membranes? (2)

Answer 7

• liquid-applied with a roller or by spraying
• sheet membranes provide a more consistent thickness, however, they may include seams and are more difficult to apply around intricate shapes

Question 8

What purpose do water stops serve?

Answer 8

concrete foundations require water stops to resist passage of water through joints at separate concrete pours

Question 9

What is bentonite?

Answer 9

a synthetic water stop used between concrete pours to seal against water penetration

Question 10

What is radon gas? (4)

Answer 10

• radon is a cancer-causing gas that occurs naturally within soils
• concentrations vary by region and locality
• where soil emissions are high, steps must be taken to protect occupants from Radon exposure
• buildings can be provided with passive or active radon control methods/systems

Question 11

What is a passive control system for radon gas? (5)

Answer 11

• place layer of gravel below slab
• place vapor barrier over gravel
• install PVC pipe in interior wall to vent Radon gas through the roof
• warm PVC pipe creates natural draft
• install electrical junction box in attic near vent for future fan

Question 12

What is an active control system for radon gas? (3)

Answer 12

• contains an in-line vent fan
• includes a system failure warning alarm
• recommended for areas with high levels of radon

Question 13

How is heat flow accomplished in basements? (2)

Answer 13

• basements must be thermally insulated to limit the transfer of heat
• this can be accomplished by insulating the interior side of the wall, the exterior side of the wall, or by integrating insulation within the wall