Why Are My Windows Foggy? Seal Failure Explained

What Causes Foggy Windows

That fog is condensation between the glass panes:

How modern windows work: - Two or three panes of glass separated by spacers - The space between is filled with air or argon gas - The unit is sealed to keep moisture out - This sealed unit is called an "insulated glass unit" (IGU)

What went wrong: - The perimeter seal failed - Humid air got into the space between panes - Moisture condensed on the interior glass surfaces - You can't reach it to wipe it away

Why seals fail: - Age (10-20 years is typical lifespan) - Poor original manufacturing - Extreme temperature cycles (hello, Ottawa) - Improper installation stressing the seal - Direct sun exposure accelerating deterioration

Does Seal Failure Actually Matter?

Yes, but maybe not as much as you'd think:

Energy efficiency impact: - Argon gas has escaped — replaced by air with higher conductivity - Insulation value drops 10-15% - Not catastrophic, but noticeable in cold weather

Visibility impact: - Can range from faint haze to completely obscured - Often worse in certain weather conditions - Progressive — usually gets worse over time

Structural impact: - None — the glass is still intact - Window still operates normally - Security unchanged

Home value impact: - Visible seal failure is noticed by buyers - Home inspectors flag it - Can affect sale price or negotiations

Bottom line: Failed seals aren't an emergency, but they should be addressed eventually.

Can Foggy Windows Be Repaired?

The short answer: rarely worth it.

"Defogging" services: - Drill holes, flush moisture, install vents - Costs $75-150 per window - Mixed results — may clear temporarily - Doesn't restore argon gas or original efficiency - Fog often returns within a few years

Our honest opinion: Defogging is a temporary fix at best. The seal is still failed, efficiency is still compromised, and you've spent money on something that may not last.

When defogging might make sense: - You're selling the house soon and want improved appearance - Single window in a set that's otherwise fine - Buying time until you can afford replacement

When it doesn't make sense: - Multiple windows with failed seals - Windows are also drafty or hard to operate - Windows are more than 15-20 years old

Glass Replacement vs Full Window Replacement

Two options for fixing seal failure:

Replace just the glass unit: - New sealed glass inserted into existing frame - Cost: $150-400 per window - Makes sense if: frames are in great shape, single window failed, budget tight - Downside: old frame, hardware, weatherstripping remain

Replace the entire window: - Complete new window including frame - Cost: $400-1,200 per window - Makes sense if: windows are old, multiple have failed, frames are worn - Upside: completely new, warranty, efficiency improvements

Our recommendation: If one window failed in an otherwise good set, glass-only replacement is reasonable. If multiple windows are failing or they're over 15 years old, replacing the full windows usually makes more sense — you'll eventually need to anyway.

Preventing Seal Failure

Can you make your windows last longer?

Factors you can control: - Quality of original window (buy from reputable manufacturers) - Quality of installation (improper installation stresses seals) - Not power-washing directly into the seal areas

Factors you can't control: - Ottawa's extreme temperature swings - Sun exposure (south and west-facing windows age faster) - Manufacturing quality of the seal itself

Average seal lifespan in Ottawa: - Budget windows: 8-12 years - Mid-range windows: 12-18 years - Premium windows: 18-25+ years

Warranties: Most quality windows have 15-20 year seal warranties. Check if your failed windows are still covered — you may be entitled to free replacement glass.