201d: Building Envelope Flashcards
Exterior weather
Air movement
Vapour (moisture)
Temperature
4 functions of the building envelope
Controlling moisture so it doesn’t break down insulation or absorb into the building
Air barrier such as poly film
Transfer heat at exterior in a controlled manner
Insulation’s purpose
Why is poly on the inside of a building?
MOIST air from heat inside can’t penetrate outwards and into the structure
What part of the envelope is a roof covering?
Weather resistance
What does siding and building paper work together to accomplish?
Repel water and keep it out of building structure from EXTERIOR sources
Downfall of mass wall
Cracks can cause building envelope failure via water pentration
Exterior cladding
Drainage cavity (air space)
Internal drainage plane (house wrap)
Rainscreen wall design
How do foundation walls repel water?
Damp proofing; helps wick and drain water down to weeping tile
Why do we install rigid insulation on the outside of foundation walls?
Insulation
Why do we install rigid insulation under concrete slabs sometimes?
Insulation from ground below a slab
Heat—>solids
Conduction
Heat—>air
Convection (oven)
Heat from a heat source
Radiation (fireplace)
Heat loss through walls
Conduction
Heat loss through ceiling FRAMING
Conduction
Heat loss prevention in ceiling
Blow in insulation MUST cover ceiling framing members
Heat loss through floor
Conduction
Heat loss through GAPS or CRACKS in framing and concrete
Convection (air)
Heat loss through foundation or slabs
Conduction
Insulated doors and windows
Prevent conductive heat loss through openings
Prevent conductive heat loss through foundation walls
Rigid insulation
Frost walls
Batt
Loose fill
Rigid
Semi rigid
Polyurethane foam
Insulation types
Whats an R value?
Measurement of thermal resistance of insulating materials?
Typical wall insulation
Batt
Typical roof/ceiling insulation
Loose fill
Bad place for expanded polystyrene…
Anywhere moisture light be involved
Typical spray foam
Polyurethane foam
Typical use for spray poly foam
Doors and window jambs and trimmers
Sound absorbing material
Increase wall mass
Break sound path
Increase sound absorption
Double drywall layers, air gaps, high R value insulation, staggered studs
Ways to increase wall mass
Why use a resilient metal channel?
Drywall not in direct contact with studs = less sound vibration transfer
Double wall and staggered studs
Break sound path of vibration
Warm air can…
Hold more MOISTURE than cold air
How is an air barrier effective?
Limits air movement between interior and exterior THROUGH the walls and ceiling
Can OSB be an air barrier?
Yeah but the edges have to be sealed
Are vapour barriers put on the exterior?
No. Typically put on the warm side of the building.
Prevent moist air from inside passing through the walls and condensing at the dew point I. The colder exterior wall system
Vapour barrier
How do we vent gables since it’s such a large space compared to a hip?
Gable end vent
Whats typically used to vent attics?
Roof vents
How do we vent crawl spaces?
Venta in opposing ends of building
How can we increase the available space for insulating the ceiling and attic?
Higher heels on trusses allows for thicker loose fill insulation
If a floor is cantilevered to the outside, do we need something in it?
Need insulation in the floor where it extends past the foundation and “floats” in the air
