Why is there condensation between my new double-pane windows in Vancouver?

Condensation between the glass panes of double-pane windows indicates a failed seal, allowing moisture to enter the insulated glass unit (IGU). This is a manufacturing defect or premature failure that requires window replacement or IGU replacement.

Understanding the Problem

When you see fog, condensation, or water droplets between the two panes of glass, the hermetic seal around the perimeter of the insulated glass unit has failed. Double-pane windows are designed as sealed units filled with dry air or inert gas (typically argon) to provide insulation. Once this seal breaks, outside air—along with moisture—enters the space between the panes. In Vancouver's humid climate, this moisture condenses when temperatures fluctuate, creating that foggy appearance that can't be wiped away from either side.

This isn't the same as condensation on the interior surface of windows, which is normal during Vancouver's wet season when warm, humid indoor air meets cold glass. Condensation between the panes means the window's thermal performance is compromised, reducing energy efficiency and potentially voiding your warranty.

Vancouver Climate Factors

Vancouver's marine climate creates particularly challenging conditions for window seals. The combination of high humidity (often 80%+ in winter), significant temperature swings between day and night, and over 160 rainy days per year puts constant stress on window seals. Coastal salt air can also accelerate seal degradation, especially in homes near English Bay, Burrard Inlet, or the Fraser River. Quality windows should handle these conditions for 15-20 years, but budget windows or poor installation can fail within 5-10 years.

Professional Assessment Required

Since these are new windows, this is likely a warranty issue. Contact your window installer or manufacturer immediately—most quality windows carry 10-20 year warranties on seal failure. Document the problem with photos and note when you first noticed it. A qualified glazier can assess whether the entire window needs replacement or if just the IGU can be swapped out, which typically costs $200-500 per window versus $400-800+ for complete window replacement.

Next Steps

Don't attempt DIY repairs—sealed units require specialized equipment and expertise. Review your warranty documentation and contact the installer first, then the manufacturer if needed. If the windows are very new (under one year), push for complete replacement rather than just IGU replacement, as early seal failure often indicates broader quality issues.