Barrier Systems within the Building Envelope Flashcards
What is the air barrier, and where is it located in the building envelope?
The air barrier is the leakage control system that prevents air from escaping or entering the building envelope. It can be located anywhere with the assembly, and it must be continuous.
What is the tested air leakage result for an air barrier?
0.02 L (sm2) or less, measured at an air pressure difference of 75 Pa
Why is the air barrier important?
- control moisture movement
- draft
- infiltration of outsood contaminants.
Multiple materials can make up one air barrier envelope
What is the function of the vapour barrier?
It provides protection from moisture damage to the structure and insulation.
The vapour barrier does not need to be coninuous, but must be located on the warm side of the insulation.
In some instances it may be part of the insulation or air barrier (6 mil poly)
What are the specifications for the vapour barrier?
It must resist the flow of water vapour from the interior, with a water vapour permeance level less than 60 ng/(Pa s m2) when measured in accordance with ASTM E96/E96M Water Vapour Transmission of Materials using the desiccant method (dry cup).
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What are the two key components of Air Barrier Approaches?
Air barriers systems comprise:
- a main air barrier material that forms a principal plane
- tapes, caulks, foams, gaskets, and other accessories used to make it continuous.
Benefits of airbarrier inside or outside?
Inside: block the entry of most air pollutants emitted from building materials.
Outside: they limit the need for air sealing around service penetrations and can be tested before significant completions
Identify the location, sections, materials and characteristics of the Sealed Polyethylene approach (SPA).
Location: Inside
Sections: Walls, attic, ceiling
Materials and characteristics:
- polyethylene (6 mil poly) with sealants and rim (header) wrap;
or sometimes - aluminum foild and tape, but needs to be supported on both sides
- Widely used in Canada
Identify the location, sections, materials and characteristics of Airtight drywall approach (ADA).
Location: Inside
Sections: Walls, attics, ceilings and foundations
Materials and Characteristics:
The main material is finished drywall, used in combination with sealants, gaskets, framing members and other rigid materials.
Also known as a structural air barrier
Identify the location, sections, materials and characteristics of poured concrete.
Location: Inside
Section: Foundation
Materials and Characteristics:
The main material is concrete
Identify the location, sections, materials and characteristics of Exterior insulation approach (EIA).
Location: Outside
Section: Walls
Materials and Characteristics:
Application and sealing of rigid foam insulation board or other panels
