Why cold air gets in — even through a "closed" window
A window keeps cold air out in two ways: the glass itself blocks bulk airflow, and the seals around the frame and sash stop air from sneaking around the edges. When you feel a draft in winter, one or both of those systems has failed. The most common culprits are degraded weatherstripping along the sash edges, cracked or missing caulk where the window frame meets the wall, and a sash that has warped or settled so it no longer presses evenly against its seal. Any of these creates a gap — sometimes invisible to the eye — through which cold outside air flows continuously whenever there's a pressure difference between indoors and out.
There's a second mechanism that people often mistake for a draft: radiant cold. Single-pane glass conducts heat outward so rapidly that the air immediately next to the window chills, becomes denser, and sinks toward the floor in a slow, invisible waterfall of cold air. You feel this on your ankles and lower legs and it registers as a draft even when there is no actual gap. Double- and triple-pane windows with low-emissivity coatings were specifically engineered to interrupt this process by trapping insulating gas between the panes and reflecting radiant heat back into the room.
Age and settling make both problems worse over time. Weatherstripping compresses and cracks. Caulk shrinks and pulls away from surfaces as a house expands and contracts through seasonal temperature swings. Window frames in older homes are often made of wood that has absorbed moisture, swelled, dried, and no longer sits true. The result is that a window that seemed fine last winter may be noticeably drafty this one — not because anything broke suddenly, but because cumulative wear finally crossed a threshold.
Drafty windows aren't all the same problem
The fix depends heavily on where and how the cold is getting in — so it's worth identifying which version of this problem you're dealing with.
What happens when you leave drafty windows unaddressed
Drafty windows aren't merely uncomfortable — they're expensive. Your heating system runs longer and harder to compensate for the heat being lost, which shows up directly on your energy bills every month. In climates with cold winters, the U.S. Department of Energy estimates that air leaks throughout a typical home account for 25–30% of heating energy consumption, and windows are a major contributor. Beyond money, persistent moisture infiltration through failed window seals can promote mold growth on interior sills and surrounding drywall, a problem that starts small and compounds over seasons.
The DOE estimates that properly air-sealing and weatherstripping windows and doors in a drafty home can reduce total heating and cooling costs by 10–20% annually. For a household spending $1,500 a year on heating, that's $150–$300 back in your pocket — typically recovered in the first winter from materials that cost less than $100 to apply. Ignoring the problem doesn't just mean discomfort; it means paying for heat that immediately escapes to the outdoors.
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What others have experienced
47 community experiences-
MK
We had two double-hung windows in our living room that were absolutely brutal — you could feel the cold air pouring off them sitting on the couch six feet away. I spent way too long assuming we needed new windows. Eventually I reapplied caulk around the exterior frames and replaced the foam weatherstripping on the sashes, total cost maybe $35 and two hours on a Saturday. The difference was genuinely shocking. That said, one window in the bedroom still radiates cold through the glass itself — that's the single-pane one, and I think that's going to need a real fix eventually.
34 found this helpful -
DP
Renter here, so my options were limited. I bought one of those window insulation film kits from the hardware store — the shrink-wrap kind you apply with a hair dryer — and honestly it made a noticeable difference on the worst window in the apartment. It looks a bit odd up close but from across the room you barely notice it. The draft from that window basically disappeared. My landlord would never spring for weatherstripping repairs so this was my only practical option and it held up the whole winter without peeling.
28 found this helpful -
SR
I want to save people some money: before you call anyone or buy anything, do the candle test. Hold a lit candle or a thin piece of tissue paper along every edge of your window frame on a cold windy day. Where it flickers or moves, that's your leak. I found two spots on one window I would never have guessed — both were at the corners of the interior trim where the caulk had pulled completely away. A $6 tube of paintable latex caulk fixed it. The main glass panel was still cold to the touch but the actual draft was gone entirely.
41 found this helpful
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