Sash windows and cavity wall insulation

[LHW]

Hello,
Trying to make our 1908 ground floor conversion warm enough to live in. We were hoping to renovate our sash windows and go with both floor and cavity wall insulation. However, I've been told we can't have cavity wall insulation because the sash window weights aren't fully boxed off and, with movement, this could result in voids forming and cause problems with damp down the line.

Does anyone have any views on this?

If this is the case, how big a job is sealing the pockets (this would require removing the entire box, I think?) and is it worth doing to be able to have the insulation?
Thanks

Quote Reply

 

[stuart45]

You could close the cavity.

 

[paulc]

The cavity was insulated here (just 50mm wide). To be honest, it made zero difference to heat loss, nor did it cut heating bills. Plugging the cold draughts have made a much more noticeable difference. Had a couple of windows where the cavity was exposed under the window board - Have put in cavity closers to seal the gap just in case there is any breezes blowing in.

 

[LHW]

The cavity was insulated here (just 50mm wide). To be honest, it made zero difference to heat loss, nor did it cut heating bills. Plugging the cold draughts have made a much more noticeable difference. Had a couple of windows where the cavity was exposed under the window board - Have put in cavity closers to seal the gap just in case there is any breezes blowing in.

Thanks for sharing your experience. Maybe we just draught proof the windows and go with the floor insulation. Thanks