This is part of our complete Portland residential window washing coverage — see our full residential window washing Portland guide for complete pricing, scope, and scheduling.

Broken Window Seals Are One of the Most Common Problems Portland Window Washers Discover

A failed window seal is not something most Portland homeowners recognise until a professional window washer points it out. The symptom — a persistent foggy or hazy appearance between the two panes of insulated glass that doesn’t clear when you wipe the exterior — is easy to dismiss as a cleaning problem. It isn’t. It’s a seal failure, and no amount of window washing will fix it.

In 15 years of washing windows in Portland, I’ve identified broken seals on hundreds of client homes — most of them had no idea the seals had failed. Some had been dealing with the foggy appearance for years, assuming it was condensation or a stubborn smear. Understanding what seal failure actually is, what causes it in Portland’s climate, and what your options are when you find it helps you make informed decisions rather than expensive ones.

What Causes Window Seals to Fail in Portland

• Age and thermal cycling — the most common cause. Portland’s temperature swings between summer highs and winter lows cause the spacer bar and sealant holding the two glass panes together to expand and contract repeatedly. Over 15–25 years, this cycling fatigues the seal material and eventually allows air and moisture to enter the sealed cavity.
• Moisture intrusion from frame failure — water that penetrates window frames (from failed caulking, gutter overflow, or moss damage) can reach the edge seal of the insulated unit and accelerate its deterioration. Portland homes with deferred exterior maintenance see seal failures at a higher rate than well-maintained properties.
• Direct sun exposure — south and west-facing windows in Portland experience the highest temperature cycling. UV exposure also degrades the butyl sealant used in the perimeter seal over time. South-facing insulated glass units typically show seal failure earlier than north-facing units.
• Pressure washing near windows — a significant cause of premature seal failure in Portland. High-pressure water directed at window frames or glass edges can force water past the edge seal. This is one reason Perfect Pays PDX does not use pressure washing near glass.

How Window Washers Spot Seals That Homeowners Miss

Professional window washers see windows from outside in specific lighting angles that homeowners rarely replicate. Standing at a distance with the window in cross-light (sun at an angle rather than direct reflection), a failed seal shows up as a distinct hazy or oil-film-like appearance between the panes that’s immediately different from surface contamination.

The tell-tale check: clean the exterior glass thoroughly and then look at the window from outside at a 45-degree angle in good light. Surface contamination disappears after cleaning. A failed seal remains visible — in fact, it often becomes more visible once the exterior glass is clean, because the contrast between the clear exterior and the contaminated inter-pane cavity becomes sharper.

What to Do When You Find a Broken Window Seal

• Option 1 — Insulated glass unit replacement — the most common solution. The failed IG unit (the double-pane glass assembly) is removed from the frame and replaced with a new unit, keeping the existing frame in place. This is typically $150–$400 per unit depending on size, and is the correct repair for most Portland homeowners.
• Option 2 — Full window replacement — warranted when the frame itself is also damaged (wood rot, seal failure, structural compromise) or when the window is significantly outdated and energy efficiency gains from full replacement justify the cost.
• Option 3 — Do nothing — a legitimate choice for failed seals on windows that are otherwise functioning (opening, closing, latching). A failed seal does reduce the insulation value of the glass unit slightly, but it does not create a structural or water intrusion problem unless the frame seal is also failing. Some Portland homeowners live with visible seal failure for years without consequence.
• What NOT to do — do not attempt to drill into the glass to “dehumidify” the cavity (internet advice that damages the glass and doesn’t work). Do not attempt to re-seal the perimeter with caulk (the failure is in the spacer bar seal, not the exterior frame caulk).