fixing insulation and plasterboard to block wall

[selfbuildextension]

Hi,

I am just starting the internal fit out of my extension which I have built myself so far.

The walls are dense concrete block and require 70mm celotex and then plasterboard.

There will be no battens. (architect spec)

I would prefer to use separate insulation and PB due to significant cost saving.

How do I fix the insulation to the blocks and then how do I fix the PB on top?

Should I be avoiding foil faced insulation?

I cat find much info online.

Thanks,
Shaun

 

[Swwils]

Use insulated plasterboards, the small cost premium is worth it in effort.

The right supplier should also be not too far off on price at all.

Some will need a little preparation before attaching to the wall, some do not. It depends on the backer used.

Ideally you will have a condensation risk calculation to tell you what insulated plasterboard to get and what vapour resistance value it should have - they are not all the same, even if a merchant claims so.

 

[selfbuildextension]

at the moment the cost comparison based on what i have been able to get quoted is

70mm PIR £26.65, 12.5 PB £6 = £33
Insulated PB 82.5 = £60

Difference is about 1k + vat

 

[mrrusty]

But now add in two lots of adhesive. For fixing insulated PB you can use either bonding compound (dabs) or foam adhesive - cost is about the same - dabs allow more potential for "positioning" of the boards on non-flat walls, foam is great if the walls are pretty flat. By rights, you should add a few mechanical fixings to stop the boards dropping off the wall in a fire... Insulated PB usually includes a VCL, and is much more rigid than separates, which makes for easier installation - it goes up like lego.