Solid wall framing Insulation - rockwool or pir

[millshq]

I have an old small barn I'm renovating into an annexe.
It's a 9" solid wall which has been previously framed out inside.

Thinking of two options for insulating the walls

1. put 50mm pir between studs behind ladders/noggins and 50mm attached to the back of the frame in space for cold bridging stop. overall 100mm
2. pack in rockwool in between studs and in void.

Initially I thought pir but I think rockwool will be simpler to install but not sure if I need to keep a small void/cavity between insulation and outer wall, although it is breathable and keeps rating is getting a bit damp.

I'm thinking as it's an old building with solid walls it needs to breath and pir board foil may cause condensation in the void between the wall and insulation where as rockwool will allow the entire wall to breath. Our main house is old solid walls so we know about making sure the walls are not sealed.

I'm guessing the plaster board will be ok if leave a gap between it and any insulation, the ladders between in pics allow for a gap.

Not looking for building regs etc for minimum insulation etc.

Pics attached

Cheers Graham

 

[noseall]

I have an old small barn I'm renovating into an annexe.
It's a 9" solid wall which has been previously framed out inside.

Thinking of two options for insulating the walls

1. put 50mm pir between studs behind ladders/noggins and 50mm attached to the back of the frame in space for cold bridging stop. overall 100mm
2. pack in rockwool in between studs and in void.

Initially I thought pir but I think rockwool will be simpler to install but not sure if I need to keep a small void/cavity between insulation and outer wall, although it is breathable and keeps rating is getting a bit damp.

I'm thinking as it's an old building with solid walls it needs to breath and pir board foil may cause condensation in the void between the wall and insulation where as rockwool will allow the entire wall to breath. Our main house is old solid walls so we know about making sure the walls are not sealed.

I'm guessing the plaster board will be ok if leave a gap between it and any insulation, the ladders between in pics allow for a gap.

Not looking for building regs etc for minimum insulation etc.

Pics attached

Cheers Graham

I'd have trapped DPM up the walls first along with a layer of PIR, BEFORE building the stud walls. Deffo wouldn't have fitted noggings yet either.

 

[freddiemercurystwin]

Or better still a dimpled membrane on the wall prior to everything else, predicting that moisture might enter the insulation is just foolhardy.

 

[millshq]

I'd have trapped DPM up the walls first along with a layer of PIR, BEFORE building the stud walls. Deffo wouldn't have fitted noggings yet either.

Hi, this was all done before we took over. DPM is already under the slab. Working with what we have already.

 

[millshq]

Or better still a dimpled membrane on the wall prior to everything else, predicting that moisture might enter the insulation is just foolhardy.

Hi, so are your saying don't worry about if moisture gets to the insulation?
TBH the wall doesn't feel that damp over the years as it's been like this for a while. As long a breathable I don't think damp will be a big issue.