Draughty windows

Introduction

A draught is air through a sash that does not seal, not a window you rebuild on day one. Test it with paper, look at the seal, tell a rotten frame from a gap. Closing the gaps does not replace fresh air.

How to tell it apart

Shut a sheet of paper in the sash and try to pull it out. If it slides free, the seal is poor at that point. Repeat along the sides, not only in one corner.

The seal is crushed, cut or loose: air passes there. If the frame is rotten or the glass is broken, tape will not close the hole.

The sash shuts but a thread of air stays in one place: the hardware may need adjusting. That is a window fitter, not a random screw.

Glass that runs, or mould on the reveal: not a draught to plug. It is damp, on IgroCasa — window condensation, or mould if the bathroom has no window.

Likely causes

• A seal that is worn or out of its groove.
• A sash that does not compress because the hardware is out of adjustment.
• A rotten frame, a twisted sash or broken glass.
• A gap under a French window, which is not a ventilation inlet.
• A draught mistaken for condensation: the glass wets even when the sash holds.

What to do now (€0)

1. Do the paper test around the whole edge and mark where the sheet slides free.
2. Look at the seal there: crushed, cut, loose. Do not cover it with three tapes if the wood is rotten.
3. If the sash shuts and the frame is sound, adhesive tape or a draught excluder is a temporary fix, cut to the gap you measured. It is not a window repair.
4. Do not cover the radiator under the window to “stop the air”.
5. Air the room anyway: on the casement, briefly, not a hopper for hours.

A small DIY step

1. The card below is an adhesive EPDM seal, a category example. Cut it to the gap you measured. It does not close a broken sash.
2. Stick it on a clean, dry frame, where the paper slid free. One strip, not a loop of tape on the glass.
3. A draught excluder under the door is a different object: it does not replace the sash seal and it does not go on a ventilation inlet.
4. Hardware, sash hinges and keeps: do not adjust them by trial if you do not know which screw does what. A window fitter.

Mistakes to avoid

• Blocking a ventilation inlet because “air comes through”.
• Taping up a rotten frame.
• Leaving the hopper open for hours instead of a short airing.
• Covering the radiator under the window.
• Taking wet glass for a draught and sealing the room still harder.

When to call a professional

A window fitter or joiner if the frame is rotten, the glass is broken, the sash will not shut or the hardware needs setting.

If, after a new seal, the paper still slides free on a sound sash, do not add tape: have the window looked at.

Safety

If the home has boilers, stoves or gas hobs, never block the ventilation inlets. A draught at the sash is not that inlet. If you smell gas: no flames, no switches, windows open, the meter tap if you can reach it, leave, the distributor’s emergency number on the bill, or 112 if there is danger. Gas and the boiler: a qualified technician, not DIY.

Widespread mould that returns, or someone in the home with breathing trouble or who is frail: a technician and, for health, a doctor. Condensation on the glass is read on IgroCasa, not fixed by plugging.

Questions people ask