Glossary · Insulation & windows
Rainscreen
Also called: rainscreen wall · drainage cavity · drained cavity · drainage gap
A small air gap behind siding or brick that lets rainwater that gets past the cladding drain away and lets the wall dry.
What it means
No cladding is perfectly waterproof. A rainscreen leaves a gap, often made with vertical strapping or the air space behind brick veneer, between the siding and the water-resistant layer behind it, so water drains and air carries moisture away. The gap shouldn't be filled with insulation or blocked at the bottom.
Why it matters in an audit
When an audit recommends exterior insulation or new siding, building in a drainage gap protects the wall from moisture damage.
Typical numbers
Reference values with their sources. Your auditor’s report gives the figure for your own house.
| What | Value | Source |
|---|---|---|
| Brick veneer air space (NRCan) | Typically 25–50 mm (1–2 in.), part of the drainage plane; don't insulate it | natural-resources.canada.ca ↗ |