Glossary · Insulation & windows
Air barrier
Also called: air barrier system · airtight layer · airtight drywall approach
The continuous layer of materials in walls, ceilings and floors that stops air from leaking through the building envelope.
What it means
An air barrier can be drywall sealed at the edges, sheathing with taped joints, house wrap, spray foam or polyethylene, as long as it's continuous and sealed at every joint and penetration. It's different from insulation, which slows heat but lets air pass, and from a vapor barrier, though one material can do both jobs.
Why it matters in an audit
Without a continuous air barrier, insulation underperforms and moist indoor air leaks into walls and attics, causing condensation, mold and ice dams.
Typical numbers
Reference values with their sources. Your auditor’s report gives the figure for your own house.
| What | Value | Source |
|---|---|---|
| Moisture moved by air vs. diffusion (NRCan) | One small air leak can let in about 100 times more moisture than diffusion | natural-resources.canada.ca ↗ |