PIR insulation and plasterboard
Discussion
I am looking to insulate an internal wall that is overly cold in winter. I am confident that this is something I can do myself .
I want to use PIR insulation with plasterboard over it. I cannot easily get PIR backed plasterboard where I live, but I can get foil backed PIR sheets and plasterboard separately. My plan is to strip the wall back to bare plaster and then stick the PIR sheets to the wall, I would then stick the plasterboard to the PIR sheets.
Is that ok or is there anything intrinsically wrong with this approach? Is something like Soudabond easy the right stuff to use?
Any advic would be appreciated.
I want to use PIR insulation with plasterboard over it. I cannot easily get PIR backed plasterboard where I live, but I can get foil backed PIR sheets and plasterboard separately. My plan is to strip the wall back to bare plaster and then stick the PIR sheets to the wall, I would then stick the plasterboard to the PIR sheets.
Is that ok or is there anything intrinsically wrong with this approach? Is something like Soudabond easy the right stuff to use?
Any advic would be appreciated.
dmsims said:
Thanks.Is the general idea of PIR boards and then plasterboard ok though?
What sort of wall is the external wall you are cladding?
You need to be aware if interstitial condensation.
Article about it here:
https://www.homebuilding.co.uk/advice/internal-wal...
You need to be aware if interstitial condensation.
Article about it here:
https://www.homebuilding.co.uk/advice/internal-wal...
dmsims said:
Will they hammer into brickwork? Some of them capitulate when facing just OSB. The PIR will stick well to the wall if the right foam is used. Would the weight of the plasterboard, if set on the floor rather than hanging wholly off the insulation, be sufficient to ever pull it all away?
It is an apartment built in 1990 (Germany). It is a maisonette apartment and the wall is the last bit before it joins the roof slope. I need to double check but I'm pretty sure it is a cavity wall. I think it is cold because it isn't insulated, I suspect the cavity is open under roof and the wind hits the wall quite hard.
It would only be around 1.2m high so I don't think it holding to the wall will be a problem. I'd stick a few mechanical fixings in anyway.
It would only be around 1.2m high so I don't think it holding to the wall will be a problem. I'd stick a few mechanical fixings in anyway.
As with other types of bonded joints the usual idea of adding some mechanical fixings is to stop it peeling off or maybe moving as it sets. Whether it's needed is debatable.
If you've ever used the proper adhesive foam to hang sheets then on a clean surface you'll know it's effectively impossible for them to come off later, at least up to the point of the material failing. For a foil backed sheet that might be the foil peeling, for paper similar.
My main concern with doing PIR and plasterboard stacked separately would be thickness buildup - you'll end up with a fairly chunky adhesive layer + twice rounds of levelling it all.
Personally I'd find a nice flat surface and a suitably spreadable adhesive and bond the plasterboard + PIR together first to recreate the factory product.
If you've ever used the proper adhesive foam to hang sheets then on a clean surface you'll know it's effectively impossible for them to come off later, at least up to the point of the material failing. For a foil backed sheet that might be the foil peeling, for paper similar.
My main concern with doing PIR and plasterboard stacked separately would be thickness buildup - you'll end up with a fairly chunky adhesive layer + twice rounds of levelling it all.
Personally I'd find a nice flat surface and a suitably spreadable adhesive and bond the plasterboard + PIR together first to recreate the factory product.
DonkeyApple said:
dmsims said:
Will they hammer into brickwork? Some of them capitulate when facing just OSB. Little Lofty said:
PIR doesn't stick too well, building a stud wall that you can insulate and then plasterboard over would probably be a better bet. As mentioned be wary off condensation, I have used this method in a garage conversion without issues though.
We have done that in a couple of properties where the walls were very uneven. It works well but you lose a fair bit of space. Currently doing another where the build up is wall —> vertical DPC —> batten (screwed through DPC to wall) —> PIR (screwed to batten), joints foil taped —> plasterboard (screwed through PIR to batten).
Hardest part with battening is getting it all straight and plumb (sometimes need spacers).
What I have done (many times) is to use 25mm celotex, fastened to the wall with 25x50 roofing batons at 400 centres.
Then fill between the batons with 25mm insulation which is obviously the same thickness as the batons.
Fix the batons with concrete screws, then fix the plasterboard with plasterboard screws to the batons.
It s worked for me, no issues with condensation or mould that I am aware of, effectively 50mm insulation and it makes a big difference to the energy performance of the room.
Then fill between the batons with 25mm insulation which is obviously the same thickness as the batons.
Fix the batons with concrete screws, then fix the plasterboard with plasterboard screws to the batons.
It s worked for me, no issues with condensation or mould that I am aware of, effectively 50mm insulation and it makes a big difference to the energy performance of the room.
LooneyTunes said:
We have done that in a couple of properties where the walls were very uneven. It works well but you lose a fair bit of space.
Currently doing another where the build up is wall > vertical DPC > batten (screwed through DPC to wall) > PIR (screwed to batten), joints foil taped > plasterboard (screwed through PIR to batten).
Hardest part with battening is getting it all straight and plumb (sometimes need spacers).
When doing a garage conversion you need to use 100mm pir so the stud takes up no more than that anyway. Minimum I use would be 50mm, cls is only 65mm so the stud only adds a few mm. But yes if space is at a premium then 25mm batten and 25mm pir is better than nothing.Currently doing another where the build up is wall > vertical DPC > batten (screwed through DPC to wall) > PIR (screwed to batten), joints foil taped > plasterboard (screwed through PIR to batten).
Hardest part with battening is getting it all straight and plumb (sometimes need spacers).
Little Lofty said:
LooneyTunes said:
We have done that in a couple of properties where the walls were very uneven. It works well but you lose a fair bit of space.
Currently doing another where the build up is wall > vertical DPC > batten (screwed through DPC to wall) > PIR (screwed to batten), joints foil taped > plasterboard (screwed through PIR to batten).
Hardest part with battening is getting it all straight and plumb (sometimes need spacers).
When doing a garage conversion you need to use 100mm pir so the stud takes up no more than that anyway. Minimum I use would be 50mm, cls is only 65mm so the stud only adds a few mm. But yes if space is at a premium then 25mm batten and 25mm pir is better than nothing.Currently doing another where the build up is wall > vertical DPC > batten (screwed through DPC to wall) > PIR (screwed to batten), joints foil taped > plasterboard (screwed through PIR to batten).
Hardest part with battening is getting it all straight and plumb (sometimes need spacers).
Don’t think we’ve ever dropped as low as 25mm. At the other end of the scale, fixing 125 or 150mm + PB gets expensive when you see the cost of screws that long.
RedWhiteMonkey said:
It is an apartment built in 1990 (Germany). It is a maisonette apartment and the wall is the last bit before it joins the roof slope. I need to double check but I'm pretty sure it is a cavity wall. I think it is cold because it isn't insulated, I suspect the cavity is open under roof and the wind hits the wall quite hard.
It would only be around 1.2m high so I don't think it holding to the wall will be a problem. I'd stick a few mechanical fixings in anyway.
If it's a 1.2m wall then to be honest, foam adhesive will work fine on its own to not just hold the insulation to the wall but also the plasterboard to the insulation. Something to consider with any mechanical fixings is that they will be going into the cold wall so will be thermal bridges and if metal, potential condensation points. It would only be around 1.2m high so I don't think it holding to the wall will be a problem. I'd stick a few mechanical fixings in anyway.
DonkeyApple said:
If it's a 1.2m wall then to be honest, foam adhesive will work fine on its own to not just hold the insulation to the wall but also the plasterboard to the insulation. Something to consider with any mechanical fixings is that they will be going into the cold wall so will be thermal bridges and if metal, potential condensation points.
Not if you batten the batten gives a degree of decoupling. ETA, it wouldn’t surprise me if the buildup thickness of 2x layers of foam adhesive would be nearly a thick as batten. It will also be less predictable and harder to level.
LooneyTunes said:
DonkeyApple said:
If it's a 1.2m wall then to be honest, foam adhesive will work fine on its own to not just hold the insulation to the wall but also the plasterboard to the insulation. Something to consider with any mechanical fixings is that they will be going into the cold wall so will be thermal bridges and if metal, potential condensation points.
Not if you batten the batten gives a degree of decoupling. ETA, it wouldn t surprise me if the buildup thickness of 2x layers of foam adhesive would be nearly a thick as batten. It will also be less predictable and harder to level.
Yes, it shouldn't be a particulary big job, easily within my own ability, I just want a bit of reassurance before starting on it.
I think I have found somewhere local that sells PIR insulated plasterboard (52mm thickness) so I will no longer have to cobble my own together.
I am talking about a 3.2m long and 1.2m high section of wall which goes from the floor up to where it joins the roof slope.
I would strip the existing wallpaper off, stick the PIR insulated plasterboard onto the wall, appropriately skim and fill gaps with plaster, wallpaper over that and repaint the wallpaper (the joys of Germans and their love of painted woodchip wallpaper) to match the rest of the room.
I think the PIR insulated plasterboard has a foil backing that acts as a moisture barrier, but if doesn't have that do I need some sort of moisture barrier?
I think I have found somewhere local that sells PIR insulated plasterboard (52mm thickness) so I will no longer have to cobble my own together.
I am talking about a 3.2m long and 1.2m high section of wall which goes from the floor up to where it joins the roof slope.
I would strip the existing wallpaper off, stick the PIR insulated plasterboard onto the wall, appropriately skim and fill gaps with plaster, wallpaper over that and repaint the wallpaper (the joys of Germans and their love of painted woodchip wallpaper) to match the rest of the room.
I think the PIR insulated plasterboard has a foil backing that acts as a moisture barrier, but if doesn't have that do I need some sort of moisture barrier?
RedWhiteMonkey said:
It is an apartment built in 1990 (Germany). It is a maisonette apartment and the wall is the last bit before it joins the roof slope. I need to double check but I'm pretty sure it is a cavity wall. I think it is cold because it isn't insulated, I suspect the cavity is open under roof and the wind hits the wall quite hard.
It would only be around 1.2m high so I don't think it holding to the wall will be a problem. I'd stick a few mechanical fixings in anyway.
My experience of top floor living in Germany (also in a maisonette with DG conversion) is that everything was insulated to an inch of it's life - and the same whether it was altbau / neubau.It would only be around 1.2m high so I don't think it holding to the wall will be a problem. I'd stick a few mechanical fixings in anyway.
I'd be surprised if they skimped on that - are you sure something hasn't come adrift or dislodged to cause the cold? Or perhaps you can get up under the roof to get a better look?
dan98 said:
My experience of top floor living in Germany (also in a maisonette with DG conversion) is that everything was insulated to an inch of it's life - and the same whether it was altbau / neubau.
I'd be surprised if they skimped on that - are you sure something hasn't come adrift or dislodged to cause the cold? Or perhaps you can get up under the roof to get a better look?
I can clearly see the exact area (external wall and roof) from one of our balconies and there is nothing wrong there. The interior of the wall is cold and this radiates to your neck/head when sitting on the sofa that is adjacent to the wall. I am trying to stop that.I'd be surprised if they skimped on that - are you sure something hasn't come adrift or dislodged to cause the cold? Or perhaps you can get up under the roof to get a better look?
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