I just moved into an old flat which has old and weathered down sash windows which let a lot of cold air in. As Scotland does get very cold at times I would like to insulate them in a cheap and efficient way. If it lasts for only a winter that would be fine, longer would be better of course.

My windows look like this more or less:

enter image description here

just that i only have 4 glass tiles (2 in the upper sash and two in the lower).

4 Answers 4


The main source of heat loss is not through the glass but through the gaps in the window frame and where the sashes rattle.

There are various ways you can reduce the air flow though the window.

The cheapest would be to install some cling film secondary glazing. This one looks like it just tapes up over the windows to keep the draughts out. Other systems use heat to shrink the film to size.

You could hang some heavy curtains. Make sure that they reach all the way to the floor and are plenty wide enough so you can have maximum gathering. If you line them as well there'll be two layers of fabric between the window and the room.

Next up is something like this from 365 Plastics. It's sheets of perspex cut to size and fastened to the windows with magnetic strips. We have this and it works quite well. The main drawback is storing the sheets in the summer.

A less visible solution, which you might want to use in association with one of the above is to renovate the windows with something like one of these draught proofing kits (others are available!). With these you replace the staff and parting beads with the supplied parts that include brush pile that forms the actual draught-proofing.

  • Thanks for your reply! Unfortunately I don't have space to hang heavy curtains, as there is no curtain bar to attach them. But the cling film secondary glazing sounds promising, especially since I only have single glazing on those windows. So if I understand properly it's just a plastic sheet that is taped over the whole glass part of the window? Question would them be: how easy is it to remove again? (since I am only renting the flat over the winter) Also the frame and sash themselves are not connected very tightly thus letting some air in as well. Any cheap ideas how to insulate that?
    – Pitt
    Oct 19, 2011 at 13:59
  • @Pitt I've not used the plastic film so don't know how easy it is to remove (sorry). Anything else I suggested would require your landlord to get involved.
    – ChrisF
    Oct 19, 2011 at 14:10
  • Thanks for the tips though. I guess it depends on how easy the double sided tape is to remove from the frame.
    – Pitt
    Oct 19, 2011 at 15:19
  • @Pit - you stick the film to the outer (fixed) frame, that way it also blocks the gaps around the moving parts. It's easy to get off with your fingernail or a knife if you are carefull
    – mgb
    Oct 20, 2011 at 15:26

I have large sash windows and what I do is fill in all the gaps with foam roll and then use big sheets of bubble wrap and tape up the edges. It helps and isn't expensive. Easy to remove too if you want to reopen windows.


I've found this instructions:

  1. Use hammer and pry bar to remove the molding from around the window.
  2. Cut a strip of foil-faced rigid foam insulation to fit snugly into the space between the side jamb and plaster or drywall.
  3. Spray some maximum-expanding polyurethane foam sealant into the space at the bottom and top of the window's side jamb.
  • 3
    Generally speaking, one wants to use minimally expanding foam around windows and doors to help ensure that the jambs don't bow and prevent operation. Are you sure you mean maximum expanding foam? If so, please edit to indicate why.
    – FreeMan
    Apr 19, 2022 at 11:52

There are several ways to protect windows from drafts. You can use Foam rubber weather sealing tape, or, for example, hang it with a thick curtain. It would be best to add double glazing. You can read more about how to insulate wooden windows in this article https://chameleon-decorators.co.uk/blog/how-to-insulate-windows/, it even has a short explanatory video

  • 1
    This probably would have been better as an edit to your previous answer instead of a whole new one.
    – FreeMan
    Apr 26, 2022 at 11:27

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