Why Bristol Windows Fog Up in November — and the Free Checks to Try Before You Call a Repairer

November in Bristol has a familiar soundtrack: rain on the roof, the kettle clicking on, and someone in the house saying the windows are steamed up again. In a Bedminster Victorian terrace, that fog often settles on the bedroom bay by mid-morning. In a newer flat near Temple Quay, it can appear on the inside of a sealed pane that has not been opened in weeks. Both look like the same problem. They are not.

First, find out where the water actually is

Run a finger across the glass. If the moisture is on the room side, it is surface condensation. It wipes away, comes back when the room cools, and is usually about how much moisture is in the air and how well that air is moving. If the mist sits inside the gap between two panes, you are looking at a different issue. That is moisture trapped inside the sealed unit, and no amount of window opening will clear it.

This distinction matters because one is often a habits-and-ventilation puzzle you can improve for nothing. The other is a glazing failure that needs a replacement unit, not a dehumidifier and not a bigger radiator.

The free things to try this week

Before you book anyone, spend a few days changing how the house breathes. It sounds boring, but it works.

• Open a window wide for ten minutes twice a day rather than leaving it on a tiny gap all day. A short purge clears moist air faster than a permanent draught.
• Check your trickle vents. In many Bristol homes they have been painted shut, taped over or blocked by thick curtains. Open them and leave them open unless the weather is genuinely wild.
• Run the extractor fan every time you cook, and let it run for ten to fifteen minutes afterwards. The same goes for the bathroom fan after a shower. If the fan is weak or noisy, that is worth fixing.
• Keep the bathroom door closed while the shower runs and put the loo seat down before flushing. Small changes reduce the moisture that ends up on bedroom glass.
• Dry washing outside when you can, or use a vented dryer. If you must dry indoors, keep the room ventilated and shut the door to the rest of the house.
• Move curtains and blinds so they do not cover radiators or sit tight against the glass. Warm air needs to reach the window surface. A curtain tucked behind a radiator is a condensation trap.
• Leave a gap between furniture and walls where possible. Air movement behind a sofa or wardrobe makes a surprising difference.

None of this costs anything except a bit of attention. If the glass clears and stays clearer, you have saved yourself a call-out.

Bedminster terraces versus Temple Quay new-builds

Older Bristol housing often has the opposite problem to newer housing. Victorian terraces in Bedminster and similar areas can be draughty, which helps moisture escape, but the ventilation is uncontrolled and uneven. Sash windows may have been sealed up, chimneys blocked and vents covered during past renovations. The result is a bedroom that feels cold and damp at the same time.

New-build flats near Temple Quay and the city centre are often much more airtight. That is good for energy bills, but it also means moisture from showers, cooking and drying clothes has fewer places to go. If every trickle vent has been taped up because of traffic noise, condensation will land on the coldest surface, which is usually the glass.

In both cases, the answer is not to seal the house tighter. It is to let moisture out without turning the room into a wind tunnel.

When it is a failed unit, not a damp problem

Here is the checklist we would use:

• The mist or droplets are trapped between the panes, not on the room side.
• The haze is there all day, not just after a shower or a kettle boil.
• One panel is affected while the others are clear.
• Wiping the inside of the room does nothing because the moisture is in the cavity.
• You can see a white, cloudy film inside the glass.
• The condensation returns within minutes even after a good ventilation routine.
• The seal around the unit looks shrunk, cracked or perished.

If that sounds like your window, it is a glazing problem. A failed sealed unit can sometimes be replaced without changing the whole frame, which is usually cheaper and less disruptive than a full window swap. It is also not a sign that your house has a damp problem in the rising-damp sense. Damp walls and mould in corners are a separate conversation about ventilation, insulation and water ingress.

What to say when you call

A useful call is short and specific. Tell the installer which room the window is in, whether the mist is inside the cavity, how old the window is if you know, and whether it is one pane or several. Send a photo taken in daylight. If you have tried ventilation and the mist remains between the glass, say so. That helps a repairer decide whether you need a sealed unit, a section replacement or a full window, rather than guessing from a vague description of foggy windows.

At C Through Windows Bristol, the honest starting point is always the same: not every misty pane needs a new window, and not every wet window is a damp house. Sort the free fixes first. If the fog is inside the glass, that is when a proper repair makes sense.