A cold draft under the door is easy to feel and usually cheap to fix. Hydro One says air leaks account for 25 to 40% of an average home’s winter heat loss, and Manitoba Hydro says sealing is often the least expensive way to get a real cut in heating costs. Here’s how to find your leaks, plus four products for the common ones.
Quick answer
Find the leaks on a cool, windy day, then match the fix to the gap: a door sweep for the bottom of a door, foam tape or weatherstripping for the sides and top, and a window film kit for windows you can’t seal another way.
A simple place to start: the Ormein door draft stopper for a gap under a door, or the Duck window insulation kit if the windows are the problem.
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Prefer to watch? Here’s the video walkthrough of how to draft-proof doors and windows.
Short version: how to find a draft in your home.
Four ways to seal a draft
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| Product | Best for | |
|---|---|---|
| Ormein silicone door draft stopper | A gap under a door up to 1.18 inches (30 mm). A self-adhesive silicone strip you cut to length. Skip it if your gap is wider than that. | See price |
| AIMINTSEN silicone door sweep, 2 in x 39 in | A wider gap under a door, up to 2 inches (about 5 cm). Peel-and-stick silicone for the inside of the door. Skip it if the draft comes in at the sides or top of the door. | See price |
| Kikerike self-adhesive foam weatherstrip tape, 2 rolls | Gaps around a door or window frame. Two rolls of 21 ft, each 1/2 inch wide and 1/4 inch thick, rated for -4°F to 140°F (-20°C to 60°C). Skip it for the gap under a door, where a sweep is the better fit. | See price |
| Duck Brand window insulation kit, up to 10 windows | Windows you can’t weatherstrip. Clear shrink film and tape for up to 10 windows; you’ll need scissors and a hair dryer, and it removes at the end of the season. Skip it for a bedroom window: Manitoba Hydro says they must be able to open at all times. | See price |
How do you find the drafts?
- Pick a cool, windy day in the fall or a cold winter day. Manitoba Hydro says leaks show up best when the air pressure difference between inside and outside is greatest.
- Turn on the exhaust fans that vent outdoors, including the clothes dryer. That pulls more air through any leaks.
- Hold a strip of light tissue or plastic near the edges of doors and windows. If it flutters, you’ve found a draft. Smoke from an incense stick works too: Hydro One says a strong leak blows it away.
- Mark each leak with chalk so you can come back to it.
Which fix for which gap?
- Under a door: a door sweep. Manitoba Hydro says a door bottom needs about 8 to 13 mm (1/4 to 1/2 inch) of clearance, and a saddle threshold needs at least 15 mm (5/8 inch). On an in-swinging door, the sweep goes on the inside face.
- Sides and top of a door or window frame: weatherstripping. Felt is cheap but only good for one season, according to Manitoba Hydro. Closed-cell rubber and tubular types last longer.
- A window that can’t be weatherstripped: Manitoba Hydro suggests a seal-and-peel sealant or weatherstripping tape, applied in the fall and removed in spring. Its guide adds that for safety, bedroom windows must be able to open at all times.
Hydro One says a properly fitted door should close firmly with no leaks at the sides, top or bottom.
Before you buy
- Measure the gap under your door and the length of frame you need to seal.
- Clean and dry the surface first. The listings for strips and tape say it helps them hold.
- Still cold after sealing? Our safe space heater guide covers what to look for in a heater for a cold room.
Sources: Manitoba Hydro, Energy Saving Guide, Booklet #1: Sealing, caulking & weatherstripping (July 2014) and Hydro One, Insulating your home. Product details come from the listings, so check the product page before you order.
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