Blog · Advice
Why windows mist up
Every autumn we get the same calls: “the new windows are misting up, something is wrong”. In the great majority of cases the windows are doing exactly what they should.
Where the moisture appears — that is the whole answer
| Where | What it means | What to do |
|---|---|---|
| On the inside | Too much humidity in the room; the glass is the coldest surface | Ventilation and heating — it is not a fault |
| On the outside | The glass insulates so well that the outside stays cold | Nothing — it is a sign that the glass is working |
| Between the panes | The glazed unit has lost its seal | A claim — the glass is replaced |
Only the third case is a fault. The first two are physics, and they appear precisely on good windows.
Why it happens more often after the windows are replaced
Old timber windows let air through on every side. Along with the heat, the moisture left as well — the house ventilated itself, at the cost of the heating bill.
New windows seal. The moisture you produce by cooking, showering, drying laundry, and breathing stays inside and condenses on the coldest surface in the room, which is the glass.
The window is not the cause. The window is where the problem shows first.
What actually helps
- Short, thorough airing. A window opened wide for five minutes, two or three times a day. A window left tilted all day cools the wall and does not change the air.
- Air the room after showering and cooking, with the door to the rest of the flat closed.
- Do not dry laundry in a closed room. One load of washing releases several litres of water into the air.
- Do not turn the heating off completely in rooms that are not used — a cold wall attracts condensation, and later mould.
- Move curtains and furniture off the window if you can. Cold air trapped against the glass makes it worse.
When it is a claim after all
If the mist is between the panes, inside the glazed unit, no amount of airing will help. The seal of the unit has failed, and the glass is replaced under guarantee.
The same applies if water keeps running on the same position in heavy rain, or if you can feel a draught on a closed sash. Those are signs of poor contact or faulty hardware — get in touch and we come out on a service visit. What you can check yourself before you call, and what is a job for the service team, is in adjusting PVC windows.
The guarantee is 10 years — on the profile it covers colour stability and geometry, and on the hardware 10 years or 10,000 openings. Report it to office@danito.rs or by phone.
Can it be prevented when you buy
Partly. Triple glazing keeps the inner surface warmer, so moisture appears less often. A warm-edge spacer between the panes moves the cold spot away from the edge of the glass, which is where condensation usually starts.
But no window solves excess humidity in the room. If four people live in the flat and laundry is dried indoors, airing is still the only remedy.
It also helps if the joint between the window and the wall is sealed: a cold, damp reveal around the frame is a common source of moisture. How that is dealt with in three zones is in RAL window installation.
Do you have a position that mists up between the panes?
That is a guarantee case. Get in touch and we come out on a service visit.
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