Ask House Spouse · Doors & Windows · Weatherstripping & Drafts
Why are my windows foggy between the panes?
Short answer
Fog between the two panes of a sealed insulated window means the seal has failed and moisture is trapped inside. The glass unit (called an IGU) can be replaced without replacing the whole window frame — usually $150–$400 per unit. It won't fix itself and it won't get better.
Why it happens in the PNW
Insulated glass units are two panes with a sealed gap (often argon-filled). PNW temperature swings and prolonged wet weather stress the perimeter seal. Once compromised, humid outdoor air enters, warm indoor air hits cold glass, and moisture condenses inside where you can't wipe it off.
What to replace
In most vinyl and aluminum windows, just the IGU comes out. A local glass shop measures, orders, and installs. You keep the frame, sash, and hardware. Cost is 40–60% of a whole-window replacement.
When to replace the window
If the frame itself is rotted (common on 25+ year old wood-clad windows in Edmonds, Ballard, Mukilteo), if the hardware is failing, or if you're already going to be repainting the exterior — replace the window. Otherwise, just the glass.
What we see on Home Health Assessments
Roughly 71% of homes older than 8 years show one or more failed caulk joints letting water into wall assemblies.
Caught early on assessment: $220–$750 · Left until failure: $1,200–$8,500
Based on real experience across Snohomish and King County, doors & windows issues like this are among the ones homeowners most often miss until they become expensive. Our Home Health Assessment catches them early — while they're still a maintenance item, not a repair.
How the Home Health Assessment worksServices we'd bring to this job
Especially common in these neighborhoods
We see this often on assessments across these Snohomish and King County cities we serve.
Related questions
Doors & Windows · Weatherstripping & Drafts
How do I stop drafts around my front door?
Replace the door sweep first (the strip along the bottom) — it's the single biggest source of PNW cold air infiltration. Then run a lit candle around the perimeter on a windy day: any flicker is a leak. Foam weatherstripping in the jamb takes 20 minutes and fixes the top and sides.
Exterior & Weatherproofing · Siding & Exterior Paint
How often should I repaint the exterior of a PNW home?
In Snohomish and King County, expect to repaint a well-prepped exterior every 8–12 years. Homes on windward exposures (south/west facing, no tree cover) hit the shorter end. The single biggest factor is the caulking and prep before paint — a cheap paint job over bad prep fails in 4 years.