The replacement of sash windows is, in many cases, completely unnecessary. There are very few instances where damage and decay cannot be repaired using the right knowledge and tools.

In cases where it is possible to carry out the repairs on a DIY basis, make sure you feel confident in your skills and have the right equipment for the job. If not, get in touch with a sash window specialist, or find a skilled carpenter who has examples of previous window work they can show you.


Then, the windows will need to be sanded back, primed and repainted — these are simple jobs for any DIYer. Old paint can be removed with acid such as Nitromors, or a heat gun.

Costs of repairing sash windows

Prices will vary based on the extent of the damage:

  • For a recondition and new draught seals (this may not include stripping, priming and painting) = £250 per sash
  • Box sash window replacement = £1,200
  • Double-glazed sash replacements only, to fit into existing frames = £500 per sash

Repairing sash windows step-by-step

Although the process will vary depending on the damage to your window, in general repairs follow this pattern:

1. The sashes are removed from the frame.

2. The glass is removed and then the old putty can be scraped away.

3. The joints are cleaned and any rotten wood is routed out.

4. Epoxy resin is used to fill any gaps and then new timber is spliced in.

5. The sash is sanded and often primed.

6. The glass is put back into place.

7. The window is finished and painted.

8. Old weatherstrips are replaced, new hardware is attached, new chains or cords are fitted, the pulleys are rebalanced or lubricated, and then the sashes are reinstated in the frames.

Our estimate: 1–2 days; £250 per sash

Glazing Requirements




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