Anacortes Window What You're Actually Seeing
Fog, haze, or a milky film trapped between two layers of glass is different from ordinary condensation on the inside of your windows. Interior condensation — the kind that wipes away with a towel — is a humidity problem in your house. Fog that stays put, sometimes with mineral streaking or a gray "cloudy" look that never clears no matter how dry the room is, means moisture has gotten inside the sealed glass unit itself, and it's not coming back out on its own.
This distinction matters because the fix is completely different depending on which one you're dealing with. One is a household humidity issue you can often correct yourself. The other means a component of the window has reached the end of its service life.
Where the Moisture Is Actually Located
| What you see | Where it is | What it means |
|---|---|---|
| Fog on inside surface, wipes off | Room-side glass surface | Indoor humidity/ventilation issue |
| Fog on outside surface, mornings only | Exterior glass surface | Normal dew point behavior, not a defect |
| Fog trapped between panes, won't wipe off | Inside the sealed glass unit | Seal has failed — glass unit needs replacing |
How a Sealed Glass Unit Works
Most windows installed in the last few decades use an insulated glass unit, or IGU — two (sometimes three) panes of glass separated by a spacer bar, with the gap between them filled with dry air or an inert gas like argon. That spacer bar typically has a desiccant inside it, a drying agent that soaks up any trace moisture left over from manufacturing. The whole assembly is sealed around the edges, usually with two layers: a primary seal that keeps the gas in, and a secondary structural seal that holds the glass together and keeps weather out.
As long as that seal is intact, the space between the panes stays bone dry, which is exactly what gives the window its insulating value. Once the seal breaks down — even a pinhole — humid outside air starts working its way in every time the temperature and pressure inside the unit shift. The desiccant absorbs what it can for a while, which is why early failures sometimes only fog up on cold mornings. Eventually the desiccant saturates, and the fog becomes constant.
Why Seals Fail
A handful of things wear down an IGU seal over time:
- Age and UV exposure — the sealant is a rubber-like compound that hardens and cracks over years of sun exposure
- Temperature cycling — the glass and spacer expand and contract at slightly different rates every time the temperature swings, stressing the seal edge
- Manufacturing defects — an uneven bead of sealant or a bad spacer joint from the factory, which can show up in as little as a few years
- Physical stress — a frame that's racked out of square from settling, a hard impact, or a window that was forced during installation
- Sustained water exposure at the sill or corner, which slowly works sealant loose from the outside in
None of these are unique to any one manufacturer — every IGU on the market has a finite seal life, typically somewhere in the 10-to-20-year range before failures start showing up, though a well-made unit in a stable frame can go well past that.
Why This Shows Up Earlier in Anacortes
Skagit County's marine climate is harder on window seals than most people expect. Salt-laden air off the water accelerates corrosion in metal spacer bars and hardware, and it degrades sealant compounds faster than it would inland. Add in the driving, wind-blown rain that Anacortes gets through the fall and winter, and water gets forced into places it wouldn't reach in a calmer climate — including corners and sill joints where a seal is already starting to weaken. Long stretches of damp, mossy weather each year also mean windows spend more of the year sitting wet rather than drying out between storms, which shortens the life of any seal that's already compromised. None of this means your windows were installed wrong — it just means seal failure tends to show up a few years sooner here than it might in a drier inland climate.
Does a Foggy Pane Mean the Whole Window Is Bad?
Not necessarily. A failed seal is a glass problem, not automatically a frame problem. If the frame, sash, and hardware are all still square, weathertight, and operating properly, in many cases only the glass unit itself needs to be replaced — the existing frame stays put. That said, a fogged pane is worth treating as a signal to have the whole window checked, not just the glass. If the fog failure was caused by a racked frame, water intrusion at the sill, or rot working into the surrounding wood, replacing the glass alone won't fix the underlying cause, and you'll likely see the same thing happen again.
Your Real Repair Options
Once a seal has failed, there's no product or service that restores the original dry gas fill and reseals it permanently — any "defogging" process that drills the glass, vents the moisture, and refills it with a drying solution is a temporary fix at best, since the original failure point in the seal is still there and will let moisture back in. The durable options come down to three levels of work:
| Option | What it involves | Best for |
|---|---|---|
| Glass unit replacement | Swap just the sealed IGU, keep the existing sash and frame | Frame and sash are square, weathertight, and in good condition |
| Sash replacement | Replace the operable sash (glass plus its frame), keep the outer window frame | Sash hardware, weatherstripping, or the sash frame itself has also worn out |
| Full window replacement | Remove and replace the entire unit, frame included | Frame is out of square, rotted, or the window is old enough that efficiency and hardware are also outdated |
Cost Factors Worth Understanding
Glass-only replacement is the least expensive route when it applies, but the price still swings based on a few things: the size and shape of the unit (custom or oversized glass costs more than a standard size), whether it's dual- or triple-pane, any special coatings or gas fills, and access — a ground-floor window is simpler to work on than a second-story unit that needs staging or a lift. If the frame turns out to be compromised once the old glass is out, that's usually when a job shifts from a glass swap to a sash or full window replacement, so it's worth getting an honest look at the frame condition before committing to the cheaper option.
What to Check Before You Call Anyone
A little of your own diagnosis up front saves time and helps you ask better questions when you do get someone out to look at it:
- Confirm the fog doesn't wipe away — if it does, it's an interior humidity issue, not a seal failure
- Check whether it's worse in cold weather and fades in warm weather — early-stage failures often behave this way
- Look at the frame and sill for soft wood, peeling paint, or visible gaps — signs the problem may go beyond the glass
- Check whether the sash opens and closes smoothly and latches tightly — binding or gaps point to a frame issue
- Note how many windows on the house are affected — one fogged unit is often just that one seal; several at once may point to a batch of windows reaching end-of-life together
- Ask any contractor you call whether they're proposing a glass-only swap or a full replacement, and why — a straight answer to this question tells you a lot about who you're talking to
What We Look For
Our standard when we're called out for a fogged window is to check the frame and sash condition before quoting anything, not after. If the frame is sound, we'll say so and price the glass-only replacement — there's no reason to sell a full window when the existing frame still has years of service left in it. If the frame or sill shows rot, racking, or ongoing water intrusion, we'll walk you through why that changes the picture and what the honest options are, including ones that cost less than a full replacement where that's realistic. Either way, you get a straight assessment of what's actually failing before any decision gets made.
If you've got a window fogging up between the panes — or you're just not sure whether what you're seeing is a glass problem or a humidity problem — we're happy to come take a look. There's a form below for a free, no-pressure estimate, and we'll give you a straight read on what's going on and what your real options are.