Introduction to Building Envelope Flashcards
Define “Building Envelope”
A building envelope also referred to as the ‘skin’ of the building, is the element of the building that separates the interior from the exterior.
How to ensure a building envelope that is functional with a long lifespan?
Good quality materials.
Name the elements of a building envelope. There are 5.
- Exterior walls
- Roof
- Openings
- Flashings
- Foundation walls
What is the typical composition of an exterior wall?
- Cladding
- Insulation
- Vapour Barrier
- Air Barrier
- Sheathing
What are the most common building envelope problems? Name at least 5.
- Rain penetration
- Infiltration of groundwater at grade and basement level
- Infiltration of snow in attics via soffits and grilles
- Frozen pipes
- Heating costs
- Efflorescence
- Spalling masonry
- Ice build-up
- Condensation in the wall cavity
- Mould
- User discomfort
What is ‘efflorescence’ in building envelopes?
Water/air transfers through the brick/mortar leaving a salt deposit, formed from calcium that is found within the material.
What is ‘spalling masonry’?
Spalling masonry is when the exterior surface of the masonry appears to chip off.
What causes ‘spalling masonry’?
Due to the freeze/thaw cycles, the moisture content in the brick/masonry expands when frozen, and then cracks.
How to prevent ‘ice-build up’ or ‘ice-damming’?
Good quality insulation
What causes ice to build up?
- Caused by a flaw in ( or inadequate ) roof insulation
- Snow melts
- Resulting water freezes in a cold area
- Creating a dam allows water to back up and penetrate shingles, also creating icicles
Condensation in a wall cavity will lead to what?
Mould growth
What are the 3 elements that create mould growth?
- Mushroom spores
- Humidity
- Organic material
What are methods used to detect mould growth?
- Air sampling detection equipment
- Trained dogs
What are building envelope design considerations and requirements? Name at least 5.
- Structural performance and movement
- Rain penetration
- Air infiltration and exfiltration
- Condensation control ( controlling water vapour )
- Thermal control
- Sound and pollution control
- Natural light
- Fire resistance
- Durabiity
- Green design
- Aesthetics
- Cost
What forces does the building envelope have to withstand?
Gravity:
- Must support its own weight
- May have to support an additional weight of building ( load-bearing wall )
Wind loads:
- Minor impact loads ( birds, airborne debris, etc. )