How to Tell If a Window Is Letting in Drafts
The simplest reliable test for a drafty window is holding a lit candle or incense stick near the frame edges on a windy day — consistent flickering or smoke movement at a specific spot pinpoints an air leak far more precisely than just feeling for a draft with your hand.
See window repair and replacement options once you’ve identified which openings are leaking.
Where to Actually Check
- Where the sash meets the frame — the most common leak point, especially on older double-hung windows.
- The bottom corners of the frame, where caulk and weatherstripping degrade fastest from water exposure.
- Where the frame meets the wall (exterior trim line) — this is a house-wrap/flashing issue, not the window unit itself, and matters for diagnosis.
Warning: A draft at the sash-to-frame line is often fixable with new weatherstripping, a relatively cheap repair. A draft at the frame-to-wall line usually means a flashing or caulking failure around the window opening, which is a different repair entirely and, if left unaddressed, can lead to water intrusion into the wall framing, not just an energy-bill issue.
When a Draft Means Replace, Not Repair
If weatherstripping and caulking address the leak but the window still feels drafty, that usually points to a warped frame or a sash that no longer closes flush — both are age/wear issues that repair can’t fully solve, and at that point full window replacement becomes the more durable fix rather than a repeated repair cycle.
A Rough Way to Estimate What a Draft Is Costing You
A single consistently drafty window can measurably affect the comfort and energy use of the room it’s in, especially on a north- or west-facing wall during Wilson’s more variable spring and fall weeks. If you notice yourself adjusting the thermostat or avoiding a specific room because it never feels quite right temperature-wise, that’s often a bigger practical cost than the utility bill alone suggests — it’s worth factoring comfort, not just dollars, into whether a repair or replacement makes sense for that particular window.
Common Questions
How can I test whether a window is actually drafty?
Hold a lit candle or incense stick near the frame edges on a windy day. Consistent flickering at a specific spot pinpoints the leak far more precisely than feeling for a draft by hand.
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