Why Are My Double-Pane Windows Foggy?
If there's condensation, haze or streaks between the two panes of your window — where no cloth can reach — the seal on the glass unit has failed. Here's what that actually means, and the fix that doesn't involve replacing the whole window.
What that fog between the panes actually is
Modern double-pane windows are built as a sealed unit: two sheets of glass, a spacer around the edge, and a pocket of dry air or argon gas in between. The spacer contains a desiccant — a drying agent — that absorbs any trace moisture sealed inside at the factory.
When the perimeter seal ages out, moist outside air slowly works its way in. Eventually the desiccant saturates, and from that point on the trapped moisture condenses and evaporates with the weather. That's the fog. Over time it leaves mineral streaks on the inside faces of the glass, which is why long-failed units look dirty even on days when the fog lifts.
Why it's so common in BC
Our climate is hard on window seals. Months of rain, high humidity and a long heating season keep a constant moisture difference between indoors and out. Then there's the sun hitting wet glass on south- and west-facing walls — heat expands the trapped air, cold contracts it — so the seal gets flexed thousands of times a year.
It's also plain age. Sealed units have a service life, and homes across Metro Vancouver are full of windows installed during the same building booms of the 90s and 2000s. If a few of yours are going foggy at once, you're not alone — and you didn't do anything wrong.
Why wiping — or drilling — won't fix it
The fog sits on the inside faces of the glass, sealed away from both sides of the window. No spray, cloth or dehumidifier can reach it. If you can wipe the condensation away, that moisture is on the room-side surface — that's a humidity issue, not a failed seal, and it's a different conversation.
You may also come across "defogging" services that drill tiny holes in the glass and rinse it. We'll be straight with you: it's a cosmetic patch at best. The insulating gas is already gone, the seal is still failed, and the fog usually returns. We rarely recommend spending money on it.
The proper fix: new sealed unit, same frame
The fix that actually lasts is a sealed-unit replacement — the most common job on our window glass repair schedule. We measure the opening, order a new unit built to match the thickness, tint and low-E coating of the original, and swap it into your existing frame. The frame, trim and siding stay untouched.
It's far cheaper than replacing the whole window, and the install itself is quick — usually under an hour per unit once the glass arrives. You get your clear view back, the insulating value back, and an end to room-side condensation streaking the glass on cold mornings. You can see examples of the finished result in our project gallery.
When full window replacement makes more sense
Sometimes the honest advice is to go bigger. If the frames are rotted or warped, the hardware is worn out, or the units are failing one after another all over the house, new glass in tired frames can be false economy. The same applies if you were already planning an upgrade — say to triple-pane or better overall performance.
Not sure which camp you're in? That's exactly what a free estimate is for — we'll tell you plainly whether your frames are worth keeping. We serve homeowners across the Lower Mainland, and if a failed unit has also left glass cracked or a room exposed, our line is answered 24/7. Reach us through the contact page or call (778) 785-1365.
Frequently asked questions
Is a foggy window just a cosmetic problem?
Mostly at first — but it costs you in quieter ways. The unit has lost its insulating value, room-side condensation gets worse through the winter, and mineral deposits slowly etch the glass until it never quite looks clean again.
Can you replace just the glass and not the whole window?
Yes — that's exactly what a sealed-unit replacement is. New glass unit, existing frame. It's the standard fix and the one we recommend most often.
If one unit has failed, will the others follow?
Not automatically, but units of the same age on the same exposed wall often fail within a few years of each other. When we visit, we can check the rest so you know what's coming.
How long does it take to fix?
The measuring takes minutes. The new unit is custom-made, so there's a short wait for the glass to arrive — then the install itself is usually under an hour per window.
Broken glass? We can be there today.
Call now for a free, no-obligation estimate. Same-day service available across Greater Vancouver — and 24/7 emergency board-up when you need it most.