Half the foggy window calls we take in Hamilton turn out to be a humidity problem, not a glass problem. It is worth two seconds with a cloth before you spend anything.
The test
Wipe the inside face of the glass. Then the outside.
- Comes off inside: indoor condensation. The glass is doing its job.
- Comes off outside: dew or morning humidity. Often a sign the unit insulates well.
- Comes off neither: the moisture is sealed between the panes. That is a failed unit.
If it is indoor condensation
Warm, moist indoor air meets the coldest surface in the room, which is the glass, and drops its water there. Showers, cooking, laundry, a humidifier and a full house all add moisture. Older Hamilton homes with new windows show it most, because the drafts that used to carry the moisture away are gone.
What helps, roughly in order of effect:
- Run the bathroom fan for the whole shower and twenty minutes after.
- Use the range hood every time you cook, and make sure it vents outside.
- Keep winter indoor humidity under about 35 percent. Lower when it is below minus 10.
- Move furniture and heavy curtains back off the glass so air can reach it.
- Open blinds during the day on the coldest windows.
Take heavy, persistent interior condensation seriously. Water sitting on sills leads to mould and rotted wood, and that becomes a bigger job than glass.
If the seal has failed
There is no repair. The unit is two panes with a spacer, a perimeter seal and a desiccant that absorbs stray moisture. Once the seal fatigues, the desiccant saturates and the water condenses inside every time the temperature drops. Drilling and drying it clears the view for a season and leaves you with holes in a unit that no longer insulates.
What replacement involves: we measure the opening, a new sealed unit is built to it, and we fit it into your existing frame. No trim removal, no drywall, no exterior work. Fitting takes under an hour once the glass arrives, usually three to seven business days after measuring.
| Situation | Cost |
|---|---|
| Standard sealed unit | $350 to $650 installed |
| Large picture window or tempered | $650 to $900+ |
| Low-E with argon | add roughly 15 to 20 percent |
| Caulking around the frame | $75 to $150 per window |
Fog in the middle of the perimeter seal
One more case. If the haze forms a band around the edge of the pane and clears in the middle, the seal is early in its failure. It will get worse, but it is not urgent. Book it before winter rather than during.
The Hamilton pattern
Failure arrives by neighbourhood, because glazing ages by build date. Subdivisions put up in the 1980s and early 1990s across the Mountain, Stoney Creek and Waterdown are in the window now. If two neighbours have already replaced units, yours is on the clock.
Not sure which problem you have? Wipe the glass, take a photo, send us the size and we will tell you straight whether you need glass.