Loft Gable Wall - Insulation

[DIY2025]

Hi,

I had a loft conversion and done and I wanted to understand how I insulate the internal gable wall.

I have been told that I should use insulation plasterboard but I am not sure what thickness. I would also like it to match the existing plasterwork.

Any guidance will be appreciated.

 

[cross thread]

Will probably state on your plans what’s required

 

[noseall]

I have been told that I should use insulation plasterboard but I am not sure what thickness.

You need to look at solid wall (by the looks of it) insulation solutions from the likes of Kingspan, Celotex or Unilin etc. For the sake of Building Regulations, you will need to achieve a minimum U value, which should be stated on your drawings. It might be as much a 75mm thick PIR + plasterboard.

I would also like it to match the existing plasterwork.

Extremely unlikely unless you already have EWI?

 

[^woody^]

Thermal plasterboard wont meet the required u-value for the external wall. You need to check your design specification for the required standard you need to meet.

And start by filling in all those empty joints to prevent air leakage

 

[cdbe]

You're probably looking at 100mm extra if you do it internally. If your stairs are coming up there you need to account for that or you'll have sore shoulders!