5.1.7 Compare advantages and disadvantages of various air barrier systems
(e.g. sealed polyethylene approach (SPA), airtight drywall approach (ADA), exterior insulation approach (EIA) and house wrap approach (HWA).
Sealed polyethylene approach (SPA) (1960-2000 inside "vapour barrier" approach
| Advantages: | Disadvantages |
|
Provides air barrier |
Does not provide rigid air barrier, possible damage from wind pressure and compression of cavity insulation |
|
Conventional scheduling |
Subject to construction damage |
|
Common practice |
Not easily repaired |
|
Located on interior of building - works to block entry of pollutants from insulated cavity |
Need double sided support to prevent tearing and billowing |
Airtight drywall approach (ADA)
| Advantages | Disadvantages |
| Provides rigid air barrier, to withstand wind pressure and compression of cavity insulation | Not well known by all building code officials |
| Can survive construction abuse | Unfamiliar to some trades |
| Located on interior of building - works to block entry of pollutants from insulated cavity | Requires Gaskets and Sealants to be consistent |
| Has durability and is easily repaired |
Exterior insulation approach (EIA) - Also called Sealed Sheathing approach
| Advantages | Disadvantages |
| Eliminates need for air sealing interior electrical and plumbing penetrations | Not all building officials are familiar with the system |
| Conventional scheduling | Will not block air pollutants from entering interior from insulation cavity |
| Rigid barrier that can withstand wind pressure and insulation compression in cavity | |
| Can form part of pressure equalized rain screen system | |
| Easily repaired before being covered | |
| Thermal break, reduced condensation forming in wall from interior moisture in cavity | |
| Allows for air tightness testing before substantial completion of home |
House wrap approach (HWA)
| Advantages: | Disadvantages |
| Eliminates need for air sealing interior electrical and plumbing penetrations | Risk of damage when extended exposure to elements and UV unprotected |
| Conventional scheduling | Will not block air pollutants from entering interior from insulation cavity |
| Can be attached to a structural sheathing that can withstand wind pressure and insulation compression in cavity | |
| Easily repaired before being covered | |
| Can form part of pressure equalized rain screen system |