Draughty sash windows are not a reason to replace them. Professional draught-proofing seals the gaps that let cold air in, makes the windows quieter and stops the rattle, while keeping the original window.
Why sash windows get draughty
A sash window needs small gaps to slide. Over time the sashes and beads wear, the timber shrinks and the gaps grow. Cold air comes in at:
- the meeting rails, where the two sashes overlap in the middle
- the sides, between the sashes and the beads
- the top and bottom, where the sashes meet the frame head and sill
- the pulley wheels and around the box frame
How professional draught-proofing works
The specialist removes the sashes and fits concealed brush seals:
- New staff beads and parting beads with brush pile seals built in, so the sashes slide against the seals.
- Seals at the meeting rails, and at the top and bottom rails.
- The sashes are usually eased and rebalanced at the same time, with new cords where needed.
Done properly, the seals are almost invisible and the windows open more smoothly than before. Most firms guarantee draught-proofing for five to ten years.
Cost
Draught-proofing typically costs £200 to £600 per window, depending on size, condition and whether it is done as part of a wider overhaul. It is cheapest to do while the sashes are already out for repairs. See our cost guide.
DIY fixes in the meantime
- Self-adhesive brush strips or V-seals on the sides of the sashes.
- Removable sealant on windows you never open.
- Heavy curtains or working shutters at night.
- A window wedge to stop the rattle.
These help, but they are no substitute for proper seals and can stop the sashes sliding if fitted badly.
Draught-proofing plus glazing
For the warmest result, draught-proof first, then consider secondary glazing or slim double glazing in the existing sashes.
