Failed Window Seals in Burnsville Homes
What a Failed Window Seal Is
Modern windows use insulated glass units (IGUs): two panes of glass separated by a spacer, with the gap sealed and often filled with argon gas to slow heat transfer. The perimeter seal is what holds that assembly together and keeps the gap dry. When the seal fails, outside air and moisture migrate into the gap. The trapped moisture condenses and you see the classic permanent haze, fog, or mineral streaking between the panes that you can't wipe away because it's on the inside surfaces.
Why It Matters in Burnsville
Burnsville's climate is hard on window seals. The temperature swing between a 95°F July afternoon and a -20°F January night expands and contracts the sealed unit thousands of times over its life, and that thermal cycling is the primary thing that eventually breaks the seal. As a result, failed seals are one of the most common findings on Burnsville homes with their original 1965–1995 windows. It rarely affects the structure, but it is a real comfort and energy issue and a near-universal negotiation item.
Common Causes
Seal failure comes from age and thermal cycling above all, but it's accelerated by south- and west-facing sun exposure, poor original manufacturing, water sitting in the sill from failed exterior caulk or flashing, and the gradual permeation of the desiccant inside the spacer. Once the desiccant is saturated, fogging is permanent.
Risks If Left Unaddressed
A fogged unit has lost most of its insulating value and its argon fill, so it leaks heat and drives up winter heating costs. The condensation can stain the spacer and, over time, contribute to sash and frame deterioration. There's no safety risk, but a house full of fogged windows is both an efficiency drain and a visible cosmetic issue that affects resale.
What We Look For
SPEC inspects every window for fogging, condensation, and haze between the panes, broken or cracked glass, failed exterior caulk and flashing, sash operation, and rot at wood sills and frames. We document which specific windows have failed seals so you have an exact count for budgeting or negotiation. We also note window age and type to gauge how many more are likely to fail soon.
Solutions & Repair Costs
You generally have two paths. Glass-only IGU replacement keeps the existing frame and swaps the sealed unit, typically a few hundred dollars per window. Full window replacement runs higher — commonly several hundred to over a thousand dollars per window installed depending on size and product — but upgrades the frame and operation too. When a large share of a home's original windows have failed, full replacement is often the more economical long-term move. We document the finding and recommend a licensed window contractor for the quote.