We replaced all our windows last year, and the house is still drafty in January. What did the contractor miss?

Even with new windows, drafts can persist if the installation wasn't done properly or if other air leakage points weren't addressed. The most common culprits are poor window installation, inadequate air sealing around the frames, or drafts coming from completely different sources that feel like they're from the windows.

Window Installation Issues are the primary suspect when new windows still feel drafty. Many contractors focus on getting the window square and level but skimp on air sealing. The gap between the window frame and rough opening should be filled with expanding foam or backer rod and sealant, not just insulation. In Calgary's extreme temperature swings, these gaps expand and contract significantly, and without proper sealing, cold air infiltrates around the entire perimeter. Check around your window frames for visible gaps, especially at the corners where the header meets the side jambs.

Improper flashing and weatherproofing can also create the sensation of drafts. If the exterior wasn't properly flashed with house wrap or building paper integration, moisture can penetrate and create cold spots that feel like drafts. This is particularly problematic in Calgary where chinook temperature swings cause rapid freeze-thaw cycles that can open up small gaps in caulking and sealants.

Other common draft sources that homeowners often mistake for window problems include electrical outlets on exterior walls, baseboards along exterior walls, attic hatches, and gaps around light fixtures. Calgary's expansive clay soils can cause foundation settling that opens gaps between the basement and main floor. Even new windows won't solve drafts coming from these areas.

Calgary's Climate Considerations make proper installation critical. With winter temperatures regularly hitting -30°C and chinook winds that can swing temperatures 20-30°C in hours, any air leakage becomes immediately noticeable. The extreme temperature differential between inside (21°C) and outside (-30°C) creates significant pressure differences that drive cold air through even tiny gaps.

Professional Assessment is your next step. Have a qualified contractor perform a blower door test or thermal imaging scan to identify exactly where air is leaking. Many window installers in Calgary offer this service, or you can hire an energy auditor. The Canada Greener Homes Grant program includes pre- and post-retrofit energy evaluations that can identify air leakage issues. If the problem is installation-related, document it with photos and thermal imaging before contacting your window contractor about warranty coverage.

What to Check Immediately: Walk around each window with an incense stick or candle on a windy day - the smoke will show you exactly where air is moving. Look for gaps in caulking, especially where the window frame meets the siding. Check that weatherstripping around the sash is intact and properly compressed when closed.

Find verified window and insulation contractors in our Calgary directory who can properly diagnose and fix air sealing issues.

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