How a house moves air
In cold weather a house behaves a little like a chimney: warm air escapes near the top while cold air is drawn in lower down. This is why sealing high openings, such as those discussed in the attic heat loss article, can reduce the draw that pulls cold air through gaps around doors and windows.
Finding leaks without special tools
- On a windy day, move a hand slowly around door and window edges to feel moving air.
- Hold a thin strip of tissue near suspected gaps and watch for movement.
- Inspect where different materials meet, since gaps tend to open at junctions.
- Check service penetrations where pipes and cables pass through walls.
Moving parts such as doors and operable windows call for weatherstripping that compresses and recovers. Fixed joints, such as the gap between a window frame and the wall, are better suited to caulk or sealant.
Common materials
| Location | Typical approach |
|---|---|
| Door perimeter | Compression weatherstripping |
| Door bottom | Sweep or threshold seal |
| Operable window sash | Weatherstripping along the meeting edges |
| Fixed frame-to-wall gap | Caulk or sealant |
| Wall penetrations | Sealant suited to the surfaces |
Weatherstripping
Weatherstripping seals the gap around a moving part while still allowing it to open and close. It wears over time and benefits from periodic inspection, particularly on the windward sides of the house that take the most weather.
Caulking and sealants
Caulk closes fixed joints that do not move. Clean, dry surfaces and a continuous bead matter more than the quantity applied; gaps in the bead leave a path for air just as an unsealed joint would.
Working with insulation, not instead of it
Sealing reduces air leakage, while insulation slows conduction; the two address different paths and work best together. For the material side of that pairing, see insulation types compared.