Fixing Drafty Windows: DIY Tips and When to Replace

Finding Where Drafts Are Coming From

Before fixing, diagnose:

The candle/incense test: On a cold, windy day, hold a lit candle or incense near window edges. Watch for flame flickering or smoke movement — that's where air is coming in.

Common draft sources: - Weatherstripping around the sash - Where the window meets the frame - Where the frame meets the wall - Around the glass itself - Through the window frame material

Hands-on test: On a cold day, run your hand slowly around the entire window perimeter. You'll feel cold spots where air infiltrates.

The plastic film test: If plastic film on the inside of your window balloons inward on windy days, you have significant air infiltration.

DIY Fixes That Actually Work

Try these before calling for replacement:

Weatherstripping replacement ($5-20 per window): - Foam tape: Easy, cheap, but wears out quickly - V-strip (tension seal): More durable, good for sliding sashes - Felt: Traditional, works well but compresses over time - Silicone bulb: Premium option, lasts longest

Caulking ($5-10 per tube): - Seal gaps where frame meets wall - Use paintable silicone for indoor visible areas - Clear silicone for less visible spots - Remove old caulk completely before reapplying

Window film ($10-30 per window): - Shrink-fit plastic creates insulating air gap - Not beautiful but very effective - Removes in spring without damage

Draft snakes ($10-20): - Fabric tubes that block drafts at the sill - Simple solution for bottom of window

Locking windows tight: - Many drafts improve simply by engaging all locks - Locks pull sash tight against weatherstripping

When DIY Fixes Won't Work

Some problems require replacement:

Warped or damaged sashes: - If the sash doesn't sit flat in the frame, no amount of weatherstripping seals it - Common in old wood windows and cheap vinyl

Damaged frames: - Rot, cracks, or separation in the frame can't be sealed - Air comes through the frame itself

Failed glass seals: - Condensation between panes means the seal is gone - Window has lost insulating gas fill

Worn hardware: - If locks don't engage or sashes won't stay in position - Sometimes hardware is replaceable; often easier to replace window

Single-pane glass: - No amount of weatherstripping compensates for single-pane inefficiency - Replacement is the only real solution

The Real Cost of Drafty Windows

Understanding what you're paying for those drafts:

Direct heating cost: - Drafty windows can increase heating bills 10-25% - For Ottawa home with $2,000/year heating: $200-500 wasted - Multiply by years until replacement

Comfort cost: - Cold spots force higher thermostat settings - Uneven temperatures throughout the house - Cold feet, condensation, frost on glass

Health cost: - Cold drafts stress heating systems - Temperature swings can affect health - Condensation can lead to mold

Payback math example: - DIY weatherstripping: $100, saves $200/year = pays back in 6 months - Window replacement: $8,000, saves $400/year = pays back in 20 years (but adds comfort + value)

The right answer depends on how bad the drafts are and how long you plan to keep the windows.

Making the Replace-or-Repair Decision

Here's our framework:

Repair if: - Windows are less than 10-15 years old - Frames and sashes are in good condition - Problem is limited to weatherstripping - You're handy and willing to DIY - Budget is tight

Replace if: - Windows are more than 20 years old - Multiple windows have problems - Frames are damaged, rotted, or warped - Windows are single-pane - Glass seals have failed - You want efficiency and comfort upgrade

The honest assessment: If your windows are over 20 years old and drafty, repairs are usually a temporary fix. You're delaying the inevitable while continuing to lose energy. Calculate whether spending $100-200 on repairs now makes more sense than putting that toward replacement.

If windows are newer and the issue is just weatherstripping, repair is absolutely worth it.