Window seals help limit heat transfer, prevent drafts and protect your home’s comfort. For double-pane windows, the perimeter seal also secures the space between the two pieces of glass.
A window seal failure occurs when this crucial seal breaks down, allowing air or moisture into the insulated glass unit. The result typically looks like cloudy glass, weaker energy performance or additional window damage.

Failed window seals will often become more noticeable as weather conditions change.
Fog, condensation and mineral deposits between glass panes are the clearest signs of failure. Unlike surface condensation, trapped moisture can’t be wiped away, both from inside and outside the home.
Drafty windows can result from worn weatherstripping, installation gaps or frame damage. Although a broken seal can worsen insulation, noticeable drafts point to a separate problem around the sash frame.
Windows that stick or won’t lock could have a warped sash, damaged hardware or shifting frame. These challenges create air and water leaks even if the glass seal stays intact.
Cracks, gaps, soft wood and water stains are all indications of frame deterioration. When the surrounding structure is damaged, replacing the glass alone won’t be enough to solve the issue.
Several factors are known to contribute to window seal failure:
Daily heating and cooling needs can be hard on older windows. The materials expand in the sunlight and contract after temperatures fall, placing repeated stress on the seals.
There are several solutions, but the right choice comes down to the window’s age, construction and overall condition.
Defogging eliminates moisture and enhances the appearance of cloudy glass. However, it typically doesn’t restore the original factory seal, insulating gas or energy performance.
Insulated glass unit replacement installs new sealed glass while maintaining the existing sash and frame. This works well when the rest of the window is in excellent condition, although matching older glass or grille patterns can be challenging.
Finally, full window replacement addresses the glass, sash, frame, weatherstripping and hardware at the same time. It offers superior long-term value when multiple components are worn or damaged.
Explore our Window Replacement Services to compare options for your home.
Before moving forward with repairs, locate your original receipt, product label and warranty paperwork. Coverage can depend on the product, installation date and cause of failure, and DIY alterations can also affect claims.
Renewal by Andersen’s custom replacement windows are made to fit your home’s existing openings. Our process brings consultation, measurement, manufacturing, installation and service together through one company.
Current transferable limited warranties include 20-year coverage on standard glass and Fibrex® material, 10-year coverage on locks, hinges and other components and two-year coverage on professional installation.
Fog between the panes indicates a problem with the glass assembly, but the entire window should be carefully inspected before choosing a solution.
Look for:
Take clear photos and refer to the installation date and previous service history. Don’t remove any labels or take the window apart before contacting the manufacturer first.
How much does it cost to replace a window seal? There’s no universal price since the work could call for defogging, a new insulated glass unit or the replacement of the entire window. Size, style, glass options, accessibility and frame condition also shape the final cost.
An inspection requires one visit to your home, while custom glass units and replacement windows require additional time for measurement and manufacturing.
When comparing your options, consider your window’s age, warranty status and overall condition. IGU replacement is worthwhile for a newer window with a sound frame, but full replacement might be the better investment when the window is old, damaged, difficult to operate or causing ongoing comfort concerns.
Homeowners are able to clean accessible glass, inspect weatherstripping and document any visible damage. Minor exterior caulk maintenance can also be manageable when you know the right product to use.
Repairing a sealed glass assembly is a more complicated process; adding caulk around the edge won’t remove moisture trapped between the panes or restore insulating gas. Removing the glass without proper training could lead to breakage, water intrusion or other warranty issues.
Our professionals are here to help you determine whether your issue involves the glass, sash, frame or installation.
Set up an inspection if you spot persistent fog between the panes, cracked glass, water stains or a sash that won’t shut securely. Professional attention is also advantageous when several windows fail within a short period or when warranty coverage could apply.
Prompt service is paramount if moisture is reaching the wall around the window. Professionals can find the source and determine whether glass replacement, sash service or a new window is the right solution for you.
The most typical warning signs are fog, condensation, haze or mineral deposits trapped between the glass panes. Surface condensation alone doesn’t mean that the seal has failed.
Exterior gaps can sometimes be recaulked while worn weatherstripping can be replaced. However, a failed factory seal inside a double-pane unit generally can’t be restored with caulk. Defogging can boost visibility, but it doesn’t fully rebuild the sealed unit.
Replacing the insulated glass unit is worthwhile when the sash and frame remain sound. If the window has wider problems, full replacement can provide better long-term value.
Failed window seals leave a big impact on your visibility, comfort and energy performance. Renewal by Andersen can assess your whole window and help you make the right choice for your home.
Schedule a Free Consultation to go over your goals today. Renewal by Andersen proudly serves Seattle, WA and the surrounding communities, including Mercer Island, Kirkland, Edmonds and Bellevue.