Draughty sash windows are one of the most common complaints in period homes, but they are also one of the easiest problems to fix. In most cases you do not need new windows. This guide covers seven fixes, from five-minute DIY jobs to professional draught-proofing, so you can choose the right one for your home and budget.
Why sash windows get draughty
Sash windows slide up and down, so they need small gaps to move. Over time those gaps grow. The timber shrinks and swells with the seasons, layers of paint stop the sashes closing properly, beads come loose, and the meeting rails (where the top and bottom sashes meet) stop lining up. Air then leaks in around the edges of the sashes, through the meeting rails and under the bottom rail.
Find where the draught is coming from
On a windy day, run the back of your hand or a lit incense stick slowly around the window. The usual culprits are:
- the gap between the two sashes at the meeting rails
- the sides, where the sashes slide against the beads
- the bottom, where the lower sash sits on the sill
- the top, where the upper sash meets the head of the frame
- gaps between the frame and the wall, sometimes hidden behind the shutters or architrave
1. Fit a better catch or sash lock
If the meeting rails do not pull tightly together, a well-fitted fastener can close the gap. Many sash locks are designed to pull the sashes together as they close. This is cheap, quick and also improves security.
2. Use temporary seals for the winter
Removable sealing tape or foam strips can be pressed into the gaps of sashes you do not open in winter. They work, but they stop the window opening, so they are best for spare rooms or as a stopgap. Avoid permanently sealing every window, as rooms still need ventilation to prevent condensation and mould.
3. Add self-adhesive draught strip
Brush or rubber strips from DIY shops can be stuck to the top of the upper sash and the bottom of the lower sash. They are cheap and easy to fit, but they tend to wear out or peel off on the sliding edges within a season or two.
4. Adjust or replace the staff beads
The staff beads are the thin timber strips that hold the lower sash in place. If they have been fitted loosely, the sash will rattle and let air in. Easing them off and refitting them a little tighter (without trapping the sash) can make a noticeable difference. Take care, as beads on older windows can split.
5. Use heavy curtains or close the shutters
It sounds simple, but lined curtains, a thermal blind or working internal shutters cut draughts and heat loss at night. If your house still has its original shutters, bringing them back into use is one of the best value improvements you can make.
6. Have the windows professionally draught-proofed
This is the long-term fix. A specialist removes the sashes, cuts a small groove into the edges and fits brush or rubber seals that are hidden from view. They usually replace the staff and parting beads with draught-proofed versions too, and ease and rebalance the sashes so they slide smoothly. Done well, it can cut draughts dramatically and reduce rattling and outside noise.
Typical UK prices are around £150–£350 per window, or £250–£450 in London and the South East, and more if it is combined with new cords and a full overhaul. Draught-proofing is currently zero-rated for VAT in the UK as an energy-saving measure, so check that your quote reflects that. Read more in our sash window draught-proofing guide.
7. Add secondary glazing
If you want to stop draughts and also cut heat loss and noise, secondary glazing is a slim second window fitted inside the existing one. It leaves the original sashes untouched, which makes it popular in listed buildings. Expect roughly £180–£400 per window. See our secondary glazing guide.
Do I need new windows?
Usually not. Replacement is only worth considering when the frames are badly rotten or have been heavily altered. A draught-proofed original sash window with good curtains or secondary glazing can perform surprisingly well. If you are weighing it up, our guide to repair or replacement will help.
Can I draught-proof a listed building?
Concealed draught-proofing is often acceptable on listed buildings because it is reversible and does not change how the window looks, but you should always check with your council’s conservation officer first. See our planning guide.
FAQs
Does draught-proofing stop the windows opening?
No. Professional draught-proofing is designed so the sashes still open and close, usually more smoothly than before.
How long does professional draught-proofing last?
Good-quality brush seals typically last 10–20 years before they need replacing, and replacing them is a simple job.
Is it worth draught-proofing sash windows?
For most period homes, yes. It is one of the cheapest ways to make a room feel warmer and quieter, and it keeps the original windows.
Who can draught-proof my sash windows?
Find sash window draught-proofing specialists near you and compare their services, experience and reviews.
