Failed double-pane sealed units
The standard insulated glass unit in most home windows, fogged or cloudy from a blown seal.
Window glass · Toronto & the GTA
Foggy Window & Sealed Unit Glass Replacement, Toronto & the GTA
A foggy window means the seal on the insulated glass unit has failed, so moisture is now trapped between the panes. Toronto Glass Repair fits a new sealed unit and reuses your existing frame, so the window looks clear again without a full replacement.
01What we cover
Foggy and sealed unit glass we replace
A sealed unit, also called an insulated glass unit or IGU, is two panes of glass bonded around a spacer with dry air or argon gas sealed between them. When that seal fails, humid air gets in and condenses, which is the haze that will not wipe off.
A misted window is not a cleaning problem, and it is not urgent. The fix is to replace the sealed unit itself.
In most homes the frame and sash stay exactly where they are, which keeps the job cleaner and cheaper than swapping the whole window.
Misted triple-pane units
Three-pane units common in newer GTA homes, replaced like-for-like to keep the rating.
Condensation between window panes
Moisture, haze or a milky film trapped inside the glass that no amount of cleaning removes.
Low-E and argon-filled units
Low-E (low-emissivity) glass has an invisible coating that reflects heat back into the room, and argon gas between the panes adds extra insulation. We match both when we replace a failed unit.
Picture, casement and slider sashes
Fixed picture windows, cranking casements and horizontal sliders that have lost their seal.
Patio and french door glass
Foggy sealed units inside sliding patio doors and glass french doors.
02Good to know
Can a foggy window be fixed?
Not by repairing the existing glass. Once the seal on an insulated glass unit fails, the cloudy window haze is permanent, and defogging tricks that drill and dry the cavity do not restore the seal or the insulation. The real fix is replacing the sealed unit.
You may have seen ads for a defogging service that drills a hole, dries out the trapped moisture and seals it back up. It can clear the fog for a while.
But the unit is no longer airtight, the gas fill is gone, and the misting usually comes back. We skip that and replace the failed unit with a fresh one built to your window's size and spec.
Your frame and sash stay in place, the old glazing comes out, the new sealed unit goes in, and the window is clear and insulating again.
Why is my window foggy inside?
Because the window seal has failed and humid air has worked its way between the panes. As temperatures swing, that trapped moisture condenses into the fog or film you see. It sits on the inside faces of the glass, where you cannot reach it to clean.
- Age and weather: most sealed units last roughly 10 to 20 years before expansion and contraction break down the edge seal, which is why fogging shows up in middle-aged windows, not new ones.
- Lost gas fill: the argon or air between the panes escapes, so insulation drops and condensation between the window panes forms.
- Where you see it: the haze is between the two panes, not on the surface, which is why wiping does nothing.
Do you replace the whole window or just the glass?
Just the glass unit, in almost every case. If your frame and sash are sound, we reuse them and fit a new sealed unit. That is faster and far less disruptive than tearing out the window.
- 1We measure the sealed unit and note the spec: pane count, thickness, any Low-E coating and gas fill.
- 2The unit is built to match, since insulated glass is made to order for the exact opening.
- 3On the fit day we remove the old glass, clean up the sash, and install the new sealed unit.
- 4We reglaze and check the seal so the new unit is weathertight in your existing frame.
03Pricing
How much does it cost to replace a foggy window?
Foggy units are priced per unit, by size and spec, not by a flat rate. Because this is planned work rather than an emergency, you get a measured quote before anything is ordered. Insulated glass unit replacement that keeps your frame is the lower-cost path compared with a full window replacement.
What drives the price:
- Unit size: a small fixed pane sits at the low end, a large picture window costs more.
- Pane count: a double-pane unit is cheaper than a triple-pane.
- Spec: plain glass is least expensive, Low-E coatings and argon fill add to it.
- Glass type: tempered or laminated units, often required near doors and floors, cost more than standard.
- Quantity: doing several fogged windows in one visit usually lowers the per-unit price.
Tell us the rough size and how many windows have fogged, and we will give you a rough range on the phone. The firm price comes after we measure the units and confirm the spec.
04No rush
A foggy window can wait, so plan it properly
Unlike a broken pane, a fogged unit is not a security or weather risk, so there is no reason to pay for an after-hours call. The one thing it costs you is insulation.
A unit that has lost its seal and gas fill no longer keeps heat in as well. If several windows have started to mist, measure them together and replace the units in one visit rather than one at a time.
05FAQ
Common questions
Is a foggy window worth replacing?
Usually yes, if the frame is in good shape. A fogged sealed unit has lost its insulating gas, so it costs you a little on heating and looks permanently hazy. Replacing just the sealed unit and keeping your existing frame restores both the clarity and the insulation for far less than a whole new window.
Does a fogged window lose heat?
Yes, some. The insulating gas that made the unit efficient escapes when the seal fails, so a fogged unit insulates noticeably worse than a healthy one. It is not an emergency, but it costs a little on heating every month the haze sits there.
How long does a sealed unit replacement take?
The visit itself is quick, often under an hour per window, but the unit has to be made to order first. We measure on one visit, the insulated glass unit is built to your size and spec, and we come back to install it once it is ready.
Will the new glass match my other windows?
Yes. We match the new sealed unit to the original spec, including pane count, thickness, any Low-E coating and the gas fill, so it performs and looks the same as the units around it.
Do you replace foggy units in patio and french doors?
Yes. Sliding patio doors and glass french doors use insulated glass units too, and they fog the same way. We replace the sealed unit in the door, and where the glass sits low or beside a door we fit tempered safety glass to match the original.
Why is there condensation on the outside of my windows?
Exterior condensation is usually just dew on a cold morning and clears on its own. It can even be a sign the unit insulates well. The fog that means a failed seal sits between the two panes, where wiping either side does nothing, and that is the one that needs a new sealed unit.
06More services
Other glass services we cover
Windows fogging up between the panes?
Tell us the size and how many, and we will measure, match the spec and replace the sealed units so they are clear again.