Drafty Windows: How to Tell If It's Time to Replace

Feel cold air near your windows? According to the U.S. Department of Energy, window drafts can come from several sources—not all require replacement.

Where Drafts Come From

According to DOE guidance, window air leaks occur at:

1. Between sash and frame: Worn weatherstripping
2. Between frame and wall: Installation gaps or settling
3. Through the glass: Crack, failed seal, or single-pane
4. Around hardware: Worn-out locks, hinges

Diagnostic Steps

According to ASHRAE and DOE, locate the draft source:

The candle test: On a windy day, slowly move a lit candle around window edges. Flame flickering indicates air movement.

The tissue test: Hold a tissue near suspected gaps. Movement indicates leaks.

Visual inspection: Look for:

• Daylight around sash edges
• Gaps between frame and wall
• Cracked or missing caulk
• Compressed or damaged weatherstripping

Fixable vs. Replace

According to the U.S. Department of Energy:

Often Fixable (No Replacement Needed)

• Worn weatherstripping → Replace weatherstripping ($20-50 DIY)
• Frame-to-wall gaps → Re-caulk or add foam ($10-30 DIY)
• Loose hardware → Adjust or replace hardware ($20-100)

Replacement Indicators

• Sash warped and won't seal properly
• Frame rotted or structurally compromised
• Gap between sash/frame even when closed and locked
• Single-pane glass (inherent limitation)

The Lock Test

According to ENERGY STAR, a simple test:

1. Close and lock the window
2. Try to rattle the sash
3. If it moves significantly, seal can't be maintained

Some movement is normal. Excessive play indicates worn components that may not be repairable.

The Bottom Line

Not all drafts mean replacement. According to DOE, weatherstripping and caulking repairs can resolve many air leaks at minimal cost. But if the sash or frame is the problem, no amount of weatherstripping will fix it.

*For all replacement indicators, see: [Signs Your Windows Need Replacing](/guides/signs-windows-need-replacing)*