Hi all,
I'm currently starting to renovate an ex-council house with a solid wall (2 bricks thick ~22cm, no cavity).
I just tore down some very old plasterboard that had suffered water damage, with the wooden battens falling apart. The root cause of the water issue has been fixed right before we bought the house but I guess to save on cost they didn't fix the wall.
Now that the wall is back to brick, instead of simply adding a damp proof membrane, battens and plasterboard i'm considering if it's not the best time to add insulation too. It will add some cost, but it's probably the best time to do it and comfort of living + added property value is probably worth it.
(picture of the wall in question -- sorry for the mess!)
I've done a lot of research on how best to go about it but would like some input if possible. The wall is not flat (it's not clear in the picture above but there is a ~2cm+ recess in the bottom quarter, and it's overall not plumb)
There is an additional point that's relevant for all the approaches above. As you can see in the picture the chimney breast has been closed and vented (the chimney stack has been removed too). How would you deal with that with the insulation? I understand that the breast needs to be vented but having a huge vent hole through the insulation will cause a thermal bridge and likely condensation in the breast. I was considering closing, make sure it's vented on the external wall and just treating the chimney breast as the external wall.
Thanks
PS. I've read quite a few posts in this forum and other places too, https://www.diynot.com/diy/threads/single-skin-wall-insulation-thick-celotex.233612/ is very relevant to the discussion here
I'm currently starting to renovate an ex-council house with a solid wall (2 bricks thick ~22cm, no cavity).
I just tore down some very old plasterboard that had suffered water damage, with the wooden battens falling apart. The root cause of the water issue has been fixed right before we bought the house but I guess to save on cost they didn't fix the wall.
Now that the wall is back to brick, instead of simply adding a damp proof membrane, battens and plasterboard i'm considering if it's not the best time to add insulation too. It will add some cost, but it's probably the best time to do it and comfort of living + added property value is probably worth it.
(picture of the wall in question -- sorry for the mess!)
I've done a lot of research on how best to go about it but would like some input if possible. The wall is not flat (it's not clear in the picture above but there is a ~2cm+ recess in the bottom quarter, and it's overall not plumb)
- Reading online a lot of suggestions suggest to go for dot and dab insulated plasterboard but considering how uneven the wall is it's probably not the best idea.
- I considered putting a vapour barrier or DPC behind the battens and fixing insulated plasterboard on top. It's easy, cost-wise it's not prohibitive but the ceilings are at 2.6m and I can't seem to find any insulation plasterboard that's not 2.4m which would result in butt joints and quite a lot of patch work to avoid a tiny 20cm strip. (and also butt joints that would need to be hidden) (and i'm a bit cautious of getting a full skim as i'm planning to do the entire house and skimming everything becomes quite expensive)
- It looks like Celotex's suggested installation method nowadays is to fix the PIR insulation (60mm+) to the wall and then batten over it and then plasterboard. I think that's mostly fine but reading into it, it looks like it's mostly suitable for flat walls as the insulation or battens won't be plumb.
- I was considering putting the battens plumb to the wall and either installing the PIR insulation between the battens and using aluminium tape/expanding foam to seal everything, or installing the PIR insulation on top of the battens and plasterboard on top.
There is an additional point that's relevant for all the approaches above. As you can see in the picture the chimney breast has been closed and vented (the chimney stack has been removed too). How would you deal with that with the insulation? I understand that the breast needs to be vented but having a huge vent hole through the insulation will cause a thermal bridge and likely condensation in the breast. I was considering closing, make sure it's vented on the external wall and just treating the chimney breast as the external wall.
Thanks
PS. I've read quite a few posts in this forum and other places too, https://www.diynot.com/diy/threads/single-skin-wall-insulation-thick-celotex.233612/ is very relevant to the discussion here