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Noticed foggy windows or condensation between glass panes? Your window seal has likely failed. Modern double or triple-pane windows rely on insulated glass units (IGUs) to keep your home comfortable and energy-efficient, but these seals don’t last forever.
What Are Insulated Glass Units?
IGUs consist of two or three glass panes separated by a spacer and sealed at the edges. The space between panes contains inert gas (usually argon or krypton) that provides excellent insulation. Many modern windows also feature low-E coatings that reflect heat, keeping your home warmer in winter and cooler in summer.
While IGUs can’t match a fully insulated wall’s efficiency, quality sealed windows come remarkably close to providing optimal energy efficiency.
Why Window Seals Fail
Even well-manufactured windows experience seal degradation over time. According to Vitro Architectural Glass, the inert gas naturally escapes at approximately 1% annually, even in properly constructed units. Poor manufacturing accelerates this process significantly.
Several factors contribute to seal failure:
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Natural pressure differentials between indoor and outdoor air cause gas to escape gradually
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Temperature fluctuations expand and contract the seal materials
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UV exposure degrades sealant compounds over time
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Transportation stress particularly over high altitudes where atmospheric pressure changes can damage seals before installation
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Improper installation creates vulnerabilities in the seal system
Signs Your Window Seals Have Failed
Visible Condensation
The most obvious sign is moisture, fogging, or hazing between glass panes. This condensation may appear and disappear based on weather conditions and temperature differences between indoors and outdoors.
Glass Distortion
Failed seals allow panes to bend slightly inward, creating visible distortion when you look at reflections in the glass. Stand outside and compare suspected windows with others—warped reflections indicate seal failure.
Difficult Operation
Windows that suddenly become harder to open or close may have seal failure causing frame distortion.
Pro tip: Before diagnosing seal failure, thoroughly clean both sides of your windows. External dirt can mimic condensation between panes.
Your Options for Failed Window Seals
File a Warranty Claim
Check your warranty documentation immediately. Most manufacturers offer 5-15 year warranties covering seal failure on a prorated basis. Windows failing early in their warranty period typically receive full reimbursement, while older failures receive proportionally less.
Important: Lifetime warranties refer to the window’s expected lifespan (as defined by the manufacturer), not your lifetime or your home’s lifespan. Labor costs are rarely covered, so budget for installation expenses separately.
Live with the Issue
In mild climates, failed seals may not significantly impact comfort or energy costs. Calculate whether increased heating and cooling expenses exceed replacement costs. If the affected window is in a rarely used room, replacement may not justify the expense.
Consider waiting until multiple windows need replacement to maximize installation efficiency and cost savings.
Professional Defogging
Specialized companies drill tiny holes in the glass, remove condensation, and install valves and new seals. While this restores visual clarity, it doesn’t replace the inert gas, meaning insulation value remains compromised. Results vary, and the fog often returns within a few years.
IGU Replacement Only
Some companies manufacture custom IGU units to your exact specifications. You’ll keep your existing frames while replacing only the failed glass unit. This works well for newer windows with frames in good condition, though installation costs approach full window replacement pricing.
Complete Window Replacement
Replacing the entire window—frame, glass, and hardware—makes sense when:
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Windows are over 15 years old
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Frames show wear, rot, or damage
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Operating mechanisms stick or fail
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You want to upgrade to newer technology
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Multiple windows need attention
Modern windows offer significant improvements in energy efficiency, noise reduction, and ease of operation compared to older models. A full-house window replacement project can dramatically reduce energy costs while improving home comfort and value.
Making the Right Decision
Consider these factors when deciding how to address failed window seals:
Age of windows: Older windows (15+ years) benefit more from complete replacement
Number of failures: Multiple failed seals suggest systemic issues warranting full replacement
Climate: Extreme temperatures make properly functioning seals more critical
Location: Windows in high-use areas like living rooms deserve priority
Budget: Balance immediate costs against long-term energy savings and comfort
Professional Assessment and Solutions
Not sure what’s best for your situation? Expert evaluation helps you make informed decisions about repair versus replacement. Professional installers can assess your entire window system, identify potential problems, and recommend solutions tailored to your home’s specific needs and your budget.
Ready to restore your home’s comfort and efficiency? Contact Expert Windows today for a free consultation. Our experienced team specializes in diagnosing window seal failures and providing cost-effective solutions, from individual repairs to complete home window replacement. To learn more about our expertise and commitment to quality window solutions, visit our About Us page. Call us now or request your free quote online at expertwindows.ie.
