pajw

Thanks Iceverge for the advice, it gives me some pointers what to do. There will be a fan in the ceiling that goes to a duct out through the roof. Thanks

I've only lived there since last year so have only experienced one winter and the bathroom didn't feel particularly cold. Had to take the plasterboard off as it was damaged removing the tiles. Just wondering if i should improve the insulation while i have the opportunity. OPtions I can think of 1) Do nothing, leave 100mm rockwool 2) Add 50mm rockwool to fill up gap without compressing rockwool. 3) Add 100mm rockwool (compressed into 140mm gap with original 100mm rockwool) 4) Remove rockwool and install 100mm PIR insulation board (leave 40mm gap) 5) install 100mm PIR and fill 40mm gap with rockwool I'm sure there are other options. Any advice about what to do would be gratefully received. Don't want to do something and end up with condensation and a rotten frame. Frame has no sign of damp after 40 yrs so don't want to cock it up. As Iceverge said in an earlier post the outer wall is probably impermeable so any moisture would dry to the inside.

Here are a couple of pictures to hopefully help explain what I am trying to do. Bathroom is above porch and has three external walls. Timber frame is made from 140x47mm timber, currently has 100mm of rockwool in the wall, Would like to improve insulation while I have the plasterboard off but not sure what would be best. External surface seems to render on ply with a waterproof membrane between the ply and timber frame. House was built in 1987 so not sure what the membrane (sorry if that is wrong word) is. It isn't roofing felt. Forgot to take a photo of it.

I'll add some pictures at the weekend. I must admit, after doing some more reading about insulation, i was beginning to suspect that using PIR might not be the best idea. I think I need something abit more breathable.

Thanks Mr Punter. I already have the plasterboard which sadly isn't insulated. Is there an insulating tape type product that I can attach to the studs before the plasterboard to help lower the bridging

I hoped I'd get some feedback or advice about insulating my timberframe but it hasn't happened. I'll try elsewhere.

I'm after some advice about insulating a timber frame. The timber frame is on the first floor and is three sides of a bathroom. Timber frame is made from 140x50mm timber and was built in the 1980's. The outside of the frame there is cement render over a layer of ply and there is a waterproof membrane between the ply and frame. Everything is watertight and bone dry. I recently removed the plasterboard inside the frame as some of it was damaged removing the ceramic tiles and i also needed to reroute pipework and electrics. Previously there was about 100mm of rockwool inside the voids in the wall and i'm going to put 100mm of Kingspan insulation board in the voids while I have the plasterboard off. My question is should i push the PIR board right into the void up to the membrane/ply or leave an air gap. The gap wouldn't be ventilated. My plan was to push the PIR right in and seal the edges with expanding foam, that would leave a 40mm void for pipes etc. I would then fit a vapour barrier and moisture resistant plasterboard on the inside of the frame. Does this sound OK. I know there will be thermal bridging through the timber frame but I'm hoping that will be negligible and am ignoring it. Thanks