Thermos Replacement
Fog between the panes? We replace the sealed glass unit — not the whole window.
What is a "thermos"?
In Quebec, "thermos" refers to a window's sealed glass unit: two panes separated by a gas-filled insulating space. Over time the seal can fail and let in moisture — that's what causes the fog or frost trapped between the panes that you can't wipe away.
Signs your thermos needs replacing
- Fog or condensation trapped between the two panes
- A whitish film or mineral streaks on the glass
- Frost between the panes in winter
- Glass that always looks dirty even after cleaning
- A cold feeling near the window
Our thermos replacement service
We replace only the foggy sealed unit — without changing the frame or the whole window. It's far more affordable than replacing the entire window, and it restores your window's clarity and insulating performance. We take the measurements, order the custom sealed unit and install it cleanly.
Why replace the thermos instead of the window
- Up to 70% cheaper than replacing the full window
- Keeps your existing frame and hardware
- Fast installation, often in a single visit
- Restores insulation and lowers heating bills
- Eliminates fog and restores a clear view
- Custom-made sealed units
We replace thermos units in Montreal, Laval, Longueuil, Brossard, Saint-Hubert and throughout Greater Montreal, 7 days a week.
25-Year Guarantee · 25+ Years of Experience
Every joint is applied with Canadian Adfast products and the expertise built over 25+ years on the job. Our work is guaranteed for 25 years — we don't leave until you're satisfied.
- 25-year guarantee
- Certified Adfast products
- Installation down to -29°C
- Available 7 days a week
Frequently Asked Questions
My window is foggy between the panes — what should I do?
That's the sign of a failed thermos (sealed unit). No need to replace the whole window: we replace only the foggy sealed glass unit, which is far more affordable. Request a free quote.
Mice are getting in through my soffits — can you help?
Yes. We seal soffits and every entry point where rodents get in. That's exactly why many exterminators refer us: getting rid of mice is pointless if they can come back through the same openings.
How long does caulking last?
Quality caulking, applied with Adfast products on well-prepared surfaces, generally lasts 15 to 25 years depending on sun and weather exposure. That's why our work is guaranteed for 25 years.
When should I redo my window caulking?
As soon as the joint is cracked, detached, blackened or hardened, or if you feel drafts near the windows. A joint that lets water through should be redone quickly to prevent structural damage and mold.
Can caulking be done in winter?
Yes. Unlike many products, ours allow installation down to -29°C. No need to wait for spring to fix an urgent infiltration.
What products do you use?
We use Adfast products exclusively — made in Canada and designed to withstand the extreme temperature swings of Quebec winters.
Do you offer a guarantee?
Yes: our caulking work is guaranteed for 25 years. We don't leave a job site until you are fully satisfied.
Which cities do you serve?
We serve Montreal, Laval, Longueuil, Brossard, Saint-Hubert, Boucherville, Saint-Bruno-de-Montarville, Saint-Lambert, Candiac and all of Greater Montreal.
How much does caulking cost?
The price depends on the number of openings, the condition of the existing joints and access. We offer a free, no-obligation quote, usually within 24 hours.
Do you work on condos and co-ownerships?
Yes. We manage multi-unit projects from start to finish, in coordination with the condo board, with a clear schedule and minimal disruption to residents.