Internal insulation - advice please

[Poondie]

I have a single skin concrete construction - I think called shotcrete.

I have removed plasterboard and 13mm polystyrene sheet to reveal a timber framework with felt to the outside of that and then about 80mm of in-situ concrete and render.

I propose to internally insulate with 70mm celotex PIR, foil taped joints between boards, ceiling, floor and internal wall, then Knauf vapourshield plasterboard, then tape & fill. This gets me to 0.28 u-value and deals with vapour barrier issues.

Q - is this correct method for internal insulation?
Q - How is it best to fix celotex and plasterboard? I was going to bond celotex to timber frame and then screwfix p'board through celotex to timber frame (110mm drywall screws)

Any ideas please

 

[thomasw]

you can render over the insulation boards you will need to put a mesh over first you can get the render ready to use in 25 liter buckets but dont forget to vent each wall

 

[Poondie]

Are you taking about external insulation? Why would I mesh and render internally?

 

[thomasw]

Are you taking about external insulation? Why would I mesh and render internally?

to stop it cracking

 

[alittlerespect]

Hi

Do a web search on 'Kingspan k17' and save yourself a lot of hassle, you can mechanically fix the boards to the timber studs that you have exposed. Then tape and joint and decorate - end of story. Obviously there are other manufacturers who provide a similar products and it will be for you to test the market to find out where you can get the best deal.

Basically you will be replacing what you took off with a thicker layer of insulation, also the PIR will act as a vapour barrier. If you want to get a bit of added value get hold of some bright foil and tack this to the uprights before you fix the insulated plasterboard in place and this will reflect some of the radiant heat back towards the room.

Regards