Fogged Glass in a Patio Door: Replace Only the Glass or the Whole Door?
If the door still slides or swings well, latches, and keeps water out at the sill, replace only the fogged glass: the fog means the seal of the glass unit has failed, and a new unit in the existing panel fixes it. Replace the whole door when the frame is rotted or bent, water gets in under it, or the panel itself is damaged. Here are the checks to run on the door first, and what to do in each case.
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Five checks to run on the door first
The fog tells you the glass unit has failed. These checks tell you whether anything else has.
1. Open and close it
A slider should run with one hand; a hinged door should swing without dragging and latch without a push. Stiff or dragging is usually rollers or hinges, which are repairs.
2. Look at the sill after rain
Water on the floor inside, swollen flooring or stains under the door point to the sill or frame, which new glass will not fix.
3. Press on the frame
Push a screwdriver tip gently into the bottom of a wood frame and the jambs. Soft, spongy wood is rot.
4. Check the panel corners
Look where the panel frame joins at the corners. Open joints, cracks or a bent panel mean the panel, not just the glass, is worn out.
5. Count the fogged units
Each panel of a slider, and each pane of a set of French doors, is its own glass unit. Often only one has failed.
Glass only or the whole door: what each finding means
| What you find | The answer | Why |
|---|---|---|
| Fogged glass, the door works fine | New glass unit only | The frame, panel and track are doing their job; only the seal of the glass has failed |
| Fogged glass, and the door is hard to slide | New glass unit and new rollers | The panel comes out for the glass anyway, so the rollers are done on the same visit |
| Fogged glass, and a draft at the closed door | New glass unit and new weatherstripping | Worn weatherstripping and an out of line panel are repairs, not a reason for a new door |
| Glass sealed into a panel that cannot be taken apart | A new panel, or a new door if no panel is made | Some vinyl doors are built so the glass cannot come out of the panel; we check yours first |
| Water under the sill, or a rotted or bent frame | A new door | New glass in a frame that leaks or is failing is money spent on the wrong part |
| Several fogged doors and windows, and a remodel planned | Price both | If the doors are being changed soon for other reasons, new glass now may not be worth it |
Hard to slide? Try the steps in why a sliding glass door is hard to open first. The repairs themselves are on sliding glass door repair.
Sliding and hinged patio doors are fixed differently
Both kinds keep the frame in the wall. What comes out is different.
A slider has a fixed panel and a sliding panel, each with its own glass unit. The fogged panel is lifted out, the glass unit replaced in the panel, and the panel set back on its rollers. The other panel is left alone if it is clear.
The glass sits in the door itself, held by stops or a frame around the glass. The unit is replaced with the door on its hinges or taken down, depending on the door. Grilles between the panes can be matched in the new unit.
Fixed glass beside or above a patio door is often a separate unit. If it has fogged too, it is replaced on its own, without touching the door.
What goes back in
The new unit is made to the size of your old one, so you get a time frame with your estimate. A few things to choose or confirm:
- Tempered safety glass. Glass in a patio door has to be safety glass. The federal safety standard for architectural glazing, published in the Federal Register, covers glass in sliding glass doors (patio type), along with other doors, storm doors and shower doors. Every new patio door unit we fit is tempered.
- Low-E. A new unit is a good moment to add a low-E coating on a sunny side. See low-E glass.
- Grilles and tint. Grilles between the panes and a tint can be matched so the door still looks like the windows beside it.
Fog on the room side that wipes off is a different problem, humidity, not a failed seal: see condensation on the inside of windows. For fogged windows as well as doors, see foggy window repair. Thinking of drying it out yourself? Here is why the DIY fixes do not last.
Send us the door, not just the fog
A few photos tell us whether the glass alone will do, before anyone comes out. We replace patio door glass, rollers, hinges and weatherstripping across Northern Virginia and Maryland, and we tell you plainly when the door itself is the problem. More on all door work: glass door repair.
- A photo of the whole door from inside, closed
- A close photo of the fogged glass and of the bottom of the frame
- Whether it slides or swings, and which panel is fogged
- Any label or stamp in a corner of the glass
Fogged patio door questions
More questions? Browse our glass repair FAQ or contact us.
Do I need a new patio door if the glass is foggy?
Usually not. Fog between the panes means the seal of the glass unit has failed, and a new unit fits in the existing panel. A new door is only needed if the frame is rotted or bent, water gets in under the sill, or the panel itself is damaged.
Can you replace the glass in just one side of a sliding patio door?
Yes. The fixed panel and the sliding panel each have their own glass unit, so only the fogged one needs replacing.
Can the fog between patio door panes be cleaned out?
Not from the room or from outside, because it is inside the sealed unit. Once the seal has failed, the lasting fix is a new glass unit.
Is patio door glass tempered?
It has to be. Glass in a patio door must be safety glass, and every new patio door unit we fit is tempered.
When is a new patio door the better choice?
When the frame is rotted or bent, water comes in under the sill, the panel corners have come apart, or the glass is sealed into a panel that cannot be serviced and no new panel is made.
Fogged patio door?
Send a photo of the whole door and the fogged panel, or call (202) 600-6220 for a free estimate.