Fall Door and Window Draft Check: Find the Leaks Safely, Seal Them in Priority Order

Home & envelope · 9 min read

A draft is heated air with an exit plan. Every gap around a door or window lets cold air in during the winter months and warm air in during the summer, and the heating and cooling systems work harder to cover the loss — BC Hydro's plain summary of why draftproofing, also known as weather stripping, is one of the simplest and most affordable ways to improve a home's energy efficiency. The scale is worth knowing before the work starts: the US Environmental Protection Agency estimates that homeowners can save an average of 15% on heating and cooling costs — or an average of 11% on total energy costs — by air sealing their homes and adding insulation in attics, floors over crawl spaces, and basements. Doors and windows are not the whole of that figure, and this guide does not pretend otherwise. They are, however, the part of the envelope a homeowner can check in one fall afternoon, with no ladder work and no special tools beyond an incense stick and a sheet of paper. This guide covers that afternoon: how to find the leaks safely, how to decide between caulk, weatherstripping, and foam, and the order to seal in so the biggest leaks in this scope close first.

DIY yard and home guides are general information only. Open-flame draft tests carry fire risk — follow the safety sequence in this guide, keep flames away from curtains and anything that can burn, and never leave a flame unattended. When in doubt, hire a professional. Stay safe.

Find the drafts: four methods, cheapest first

BC Hydro lists four ways to identify drafts around windows and doors, and they sort naturally by cost. First, the senses: a visual inspection comes before any test — look for cracks, gaps, and signs of wear in the caulking around windows and the weatherstripping around doors, and look for daylight peeking through the edges of door frames. The hand test is the same idea with feeling instead of sight: on a cool, windy day, move a hand slowly around window and door frames and feel for a temperature drop or a slight breeze. Second, the paper test for doors and operable windows: close the door or sash on a piece of paper, and if the paper pulls out easily without resistance — or, in the sharper version, slides back and forth or comes out without tearing — the seal is not tight and air is likely leaking through. Third, the smoke test, covered in its own section below because it is the precise method and the one with a flame attached. Fourth, the instruments: BC Hydro's thermal detector method points a detector at any suspected spot, and a change of 5°C or more in either direction identifies a leaky spot; beyond that sits the professional option, a blower door test, where energy auditors use a powerful fan to evaluate the overall airtightness of the home. A useful extra check from BC Hydro costs nothing at all: the noise check. Open a window or door a fraction and listen to the outside noise level, then close it — if the outside noise is still clearly audible, there is a draft, because a good seal cuts out most of the noise. Run the free methods on every exterior door and operable window, and reserve the smoke test for the frames where the hand and paper tests disagree or say nothing.

The safe way to run a smoke test

The smoke test is where the published advice contradicts itself, and the contradiction matters. Some guides recommend a candle; the safer consensus is to skip the candle entirely and use incense or a smoke pen instead — an incense flame is smaller, and a smoke pen has no flame at all. The method itself is simple: on a cool and windy day, light a stick of incense and hold it close to the areas where air might be leaking; if the smoke moves back and forth, or is blown out, there is a leak. The furnace question splits the sources, and both halves are about different setups, so both belong in the procedure. For a plain smoke test, still the indoor air — one Canadian guide's version has the furnace and any fans turned off — so the smoke's movement reflects the leak, not the ventilation. For the amplified version, where exhaust fans run to depressurise the house and pull air through the leaks, the order reverses and safety comes first: turn off gas and oil appliances such as the furnace and water heater before running the fans, which is the energy auditor guidance's stated first step, and turn the appliances back on when the test is done. Whichever version runs, the flame rules do not change: keep incense away from curtains and anything else that can burn, and never leave it unattended. A draft test that starts a curtain fire has found the most expensive leak in the house, and it is not an air leak.

Caulk, weatherstripping, or foam: the decision rule

Once a leak is located, one question decides the material: does the part move? The US Department of Energy states the rule directly — caulk is generally used for cracks and openings between stationary house components, such as around door and window frames, and weatherstripping is used to seal components that move, such as doors and operable windows. The Department adds that caulking and weatherstripping are two simple and effective air-sealing techniques that offer quick returns on investment, often one year or less. BC Hydro supplies the matching warning from the other direction: when sealing cracks and gaps around windows and doors, do not apply caulking or double-sided tape in a way that seals the windows and doors shut — they still have to open and close as needed. Foam sits between the two: adhesive foam weatherstripping is still weatherstripping, applied to moving parts, while caulk and spray foam handle the stationary gaps where ducts, vents, pipes, and cables enter or exit the home. The same Department of Energy guidance carries one restraint worth keeping: it is unwise to rely on air leakage for ventilation, and the recommended strategy is to reduce air leakage as much as possible while providing controlled ventilation as needed — seal the accidental holes, not the house's ability to breathe on purpose.

Weatherstripping types compared

Inside the weatherstripping row of that table, the types divide by gap and traffic. Foam tape — open-cell or closed-cell foam with an adhesive backing — is best suited to small, irregular gaps and provides a cushion when compressed; closed-cell foam offers better moisture resistance and durability than its open-cell counterpart, and BC Hydro calls foam the champion inside door frames, applied to the part of the frame that touches the exterior side of the door or window after the surface is cleaned and the length measured. Tubular weather stripping, made from rubber, vinyl, or silicone with a hollow or sponge-filled profile, is effective for larger, more consistent gaps: the tube compresses when the door or window closes, creating a durable seal well suited to high-traffic areas such as entry doors. V-strips, also called tension seals, fold a flexible metal or plastic strip into a V that springs open to bridge a gap; they are durable, typically installed along the sides of double-hung windows or door jambs, and BC Hydro rates V-seal as great for sliding windows and for the top and sides of doors. The door sweep is the specialist: an aluminum or vinyl attachment with a brush, felt, or vinyl flap that seals the gap between the door bottom and the threshold — the one gap none of the tapes can reach. Match the type to the traffic as much as to the gap: the front door that opens twenty times a day earns the tubular seal, while the bedroom window opened twice a year is honestly served by foam tape.

Priority order within doors and windows

One honesty note before the order: energy guidance is consistent that the biggest leaks in a typical home are usually in the attic and basement, and those deserve sealing before money goes to extra window film. This guide's scope is doors and windows, and inside that scope the order still matters. Exterior doors come first: they carry the largest moving gaps, the threshold gap at the bottom is the single widest opening in the scope, and a door sweep is an inexpensive fix — BC Hydro notes door sweeps at major home renovation stores for as little as $9. Operable windows come second, starting with the ones on the windward side and the ones in heated rooms that sit occupied all evening; a window nobody opens gets its sash sealed with the same V-strip, but it queues behind the windows that fight the weather daily. Stationary frame gaps come third — the caulk work around frames is unglamorous and permanent, and it is what stops the slow leaks the smoke test draws as a steady sideways pull rather than a flicker. Exterior-wall outlets and switches close the list: individually small, collectively real, and nearly free to fix, with foam gaskets at as little as $1 each. Sealing also buys quiet and cleanliness alongside the heat: a well-sealed envelope reduces noise from outside and keeps pollen, dust, and insects from entering — benefits that show up in the first week, unlike the heating bill, which argues its case in January.

The procedure, in order

1. Pick a cool, windy day and close all exterior doors and windows. Drafts announce themselves when the pressure difference is working.
2. Inspect visually first: cracked caulk, flattened or torn weatherstripping, and daylight at door-frame edges go on the list before any test runs.
3. Run the hand test slowly around every exterior door frame and operable window; mark each spot where a temperature drop or breeze is felt.
4. Run the paper test on each door and sash: close it on a sheet of paper at several points around the frame. Paper that pulls out without resistance marks a failed seal.
5. Smoke-test the maybes with incense or a smoke pen — never a candle, never near curtains, never unattended. Still the indoor air for the plain test; for the fan-amplified version, turn gas and oil appliances off first and back on afterwards.
6. Sort every confirmed leak with the decision table: stationary gap to caulk, moving part to weatherstripping, door bottom to a sweep, exterior-wall outlet to a foam gasket.
7. Seal in priority order: exterior doors (sweep first, then jambs), then operable windows, then stationary frame caulk, then outlet gaskets — with the power off at the breaker before any cover plate comes off.
8. Re-test each sealed spot with the paper test and a hand pass. A seal that makes the door hard to close is too thick — step down a size rather than forcing the latch all winter.

What success looks like: on the next windy evening, the paper stays gripped at every point of every exterior door, the incense smoke rises straight past the frames that flickered before, the closed door cuts the street noise the way BC Hydro's noise check describes, and no door or window has been sealed shut in the process. The house still opens, closes, and ventilates on purpose — it has simply stopped doing so by accident.

FAQ

Can a candle be used instead of incense? The safer guidance says skip the candle: incense or a smoke pen does the same job with a smaller flame or none at all. If incense is used, keep it away from curtains and anything that can burn, and never leave it unattended.

Is a drafty room always an air leak? Not always — a cold single-pane window chills the air beside it and can feel like a draft with no air moving. The tests separate the two: run the hand or incense test at the frame rather than at the glass. Movement means a leak to seal; a cold feel with no movement points to the glass itself, where BC Hydro's answer for older single-pane windows is insulating film, not weatherstripping.

What if every door and window fails the paper test? That pattern suggests the house's leakage is larger than this scope. Seal the doors and windows anyway — the materials are cheap and the Department of Energy puts the payback at often one year or less — and then consider the professional step BC Hydro names, a blower door test, so an auditor can evaluate the whole envelope, attic and basement included.