What plasterboard and insulation should i use.

[vallumlj]

I have just studded half of my garage out to make a room that I will use every now and then. The back wall is single skin brick, one side wall is a neighbours garage, the other side is the house wall so should be insultated and the front will be a fake wall with a door in.

My questions are what type of plasterboard should i use? I am going to use 12.5mm but do i need sound,wall,vapour or moisture boards.

I was planning on using rockwall for insulation and have room to come out 110mm. what type should i use and where best it to buy it from ?

Thanks for the help

 

[ajrobb]

The external back wall could be a problem. You should use treated* timber against external bricks and moisture resisting insulation. You could use Crown DriTherm cavity slabs or PIR (typically Celotex foam slabs or Kingspan K18 foam backed plasterboard). If you use mineral wool insulation, you'll need a separate vapour barrier on the warm side (either 2 coats drywall sealer paint, polythene sheet or foil-backed plasterboard). With PIR you don't need a separate vapour barrier.

*If you use Celotex or similar PIR, you put the Celotex against the brick and batten on the warm side (don't need treated wood then).

• Consider moisture resistant plasterboard if the room is going to be mostly unheated.
  If it is going to be a music room, you could use two layers of Soundbloc plasterboard on resilient bars.
  If you can skim then you can use cheap square-edged baseboard.
  Otherwise you can use tapered-edge plasterboard and tape-and-fill the joints.

 

[vallumlj]

I have already screwed the wood to the wall and forgot about the Dpm. Are you saying If I used celotex wall boards I wouldnt need to use anything else eg I would not need to treat the wall. What type and thickness should I use.

Thanks for the help

 

[ajrobb]

http://www.celotex.co.uk/Applications/Wall-Insulation/Solid-masonry-walls-Internal

 

[vallumlj]

Thanks ajrob for the link. Celotex looks the easist and best to do it. So let me get this right if i used celotex i don't need to use anything else on the wall i just need to keep the celotex off the wall.

If the gap is 100mm big and I use 100mm celotex it will touch the wall would i be best using 75/80mm.

Thanks for the help.

 

[ajrobb]

No, it's easier than that - Celotex directly on brick held in place with vertical 19mm deep battens at 400mm centres fixed through Celotex. Horizontal battens at top and bottom. Ideally tape joints in Celotex to complete vapour barrier. Screw ordinary plasterboard to battens. You can use the space behind the plasterboard as a service cavity. The sealed reflective cavity behind the plasterboard has an R-value of 0.6 (equivalent to an extra 15mm PIR foam).

There is a PDF-file available from the link I gave that gives detailed instructions. You have to fill in a request form to get it but it's free.

If the timber you've already put up is treated, it might be cheaper to go with Crown DriTherm cavity slabs. Again, they can touch the brick.

 

[vallumlj]

I have studed the wall already. What would you say my best Option is now.

Thanks

 

[ajrobb]

I have studed the wall already. What would you say my best Option is now.

If the timber you've already put up is treated, it might be cheaper to go with Crown DriTherm cavity slabs. Again, they can touch the brick.

 

[vallumlj]

I will double check the wood I think it is Cls stud from jewsons so hopefully it is treated. If it is I can put the slabs in and they can touch the brick. Do I need to do anything else to the brick

 

[vallumlj]

The wood is 4x2 c16 treated.

This is a old picture I have now added all the noggins.

A picture is a 1000 words. Would you still recommend the slabs now you have seen the picture. Would I use a vapour check board on that wall ?

What plasterboard should i use for the other walls and ceilings.

Thanks for all the help.

 

[ajrobb]

I should explain that I am not a professional builder. I have a single-skin Georgian bathroom to insulate, so have done some research. The problems you face look pretty similar.

I suggest you have a look at the British Gypsum Site Book. If the garage floor is below the damp course and you want to leave the place unheated much of the time, it might get quite humid. You could use moisture resistant board to cope with the humidity when cold. Duplex (foil-backed) plasterboard is quite expensive when you can get a vapour barrier from two coats of drywall sealer. 1200x455x100mm Crown DriTherm slabs should fill between the timbers you've got. A pack of 12 might do that end wall. You might notice some cold bridging by the timbers, which can attract a bit more dirt (due to Brownian motion).

I am a bit concerned that you haven't allowed for the ceiling plasterboard to reach the walls. This would normally act as a fire barrier to protect the roof timbers for 30 minutes. On the other hand, a modern garage should be built to contain a fire from the rest of the house.