What causes drafts around windows even when they're closed?

Drafts around closed windows are typically caused by worn weatherstripping, poor installation, or settling that creates gaps between the window frame and the rough opening. The most common culprit is deteriorated weatherstripping around the sash, but air can also leak through gaps in the frame itself or around the perimeter where the window meets the wall.

Weatherstripping Problems
Over time, the rubber or foam weatherstripping around your window sash compresses, cracks, or pulls away from the frame. This is especially common in Ottawa's climate where extreme temperature swings cause materials to expand and contract repeatedly. You'll often feel drafts most noticeably around the meeting rails of double-hung windows or along the sides of casement windows where the weatherstripping has failed.

Installation and Structural Issues
Poor original installation can leave gaps between the window frame and the rough opening that were never properly sealed with spray foam or caulking. House settling over time can also create new gaps or enlarge existing ones. In older Ottawa homes, you might also have single-pane windows with loose-fitting sashes that simply can't seal tightly due to their age and design.

Ottawa Climate Considerations
Our harsh winters make even small air leaks very noticeable, and the temperature differential between inside and outside air creates strong pressure differences that pull cold air through any available gaps. Ice damming and freeze-thaw cycles can also damage exterior caulking around window frames, creating new pathways for drafts.

Solutions and Next Steps
Start by checking and replacing weatherstripping - this is a DIY-friendly fix that costs under $50 per window. For gaps around the frame perimeter, you'll need exterior caulking or interior spray foam. However, if multiple windows are drafty or you're dealing with old single-pane units, replacement with modern triple-pane windows will eliminate drafts while dramatically improving energy efficiency. For a comprehensive assessment of your window draft issues and energy-efficient replacement options, request a consultation from Ottawa Window Pros.

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