Drafty doors: what to fix, and in what order

A door is not one seal. It is four: the gap under the slab, the two vertical jambs, and the head above it. Air will use whichever of those is open, and closing one while leaving the others simply moves the draft along the frame. That is why so many people fit a door sweep, feel pleased for a day, and then notice the cold has reappeared at shoulder height.

The good news is that the whole opening is cheap to fix. A sweep and a roll of weather stripping together cost about as much as a takeout meal, and between them they close every path on a typical door. The work is under an hour once you have measured.

The order to work in

1. 1Measure the gap under the door at the latch side, the middle and the hinge side. Take the largest. If they differ by more than about a quarter inch, your floor is uneven and that changes which part you buy.
2. 2Measure the frame gap with the index-card method: fold cards until they just fill the gap between the door and the stop. Each card is about 0.01 inch.
3. 3Buy the parts whose published dimensions cover those numbers — not the ones on the end cap, and not the biggest one in case.
4. 4Fit the frame first, then the bottom. Fitting a sweep and then adding a thick frame seal can stop the door latching, which means doing the sweep twice.
5. 5Re-test with a lit incense stick once both are on. Anywhere the smoke bends, something is still open.

Which part solves which symptom

What it costs

This category is cheap, and the price range is narrow enough that buying the good version of a part is rarely the wrong call. A screw-on aluminum sweep and a roll of EPDM weather stripping between them handle a full exterior door. A draft stopper is in the same band and needs no tools at all. The expensive mistakes here are not products — they are buying twice because the first part did not fit, and buying an adhesive part for a surface it cannot stick to.

We do not print prices in our copy. Every buy button on this site shows the live retailer price when we have it and says Check price when we do not, which is honest about the fact that prices in this category move week to week. There is more on that in how we pick.

The two mistakes that account for most failures

• Buying before measuring. Nearly every disappointing door seal is a sizing failure, not a quality failure. The part arrives, it is well made, and it does not reach the floor.
• Sticking adhesive to a surface that cannot hold it. Textured steel doors, bare wood, freshly painted jambs and cold rooms all defeat pressure-sensitive adhesive. Clean, smooth, cured, and above 50 F — or use screws.

If the door checks out and the room is still cold, the leak is probably somewhere else entirely. How to find drafts in your house has five tests that need nothing you do not already own.