Party garage wall insulation methods - help!

[Mr Punter]

You may be overthinking this.  Independent stud wall (95mm timber or 70mm metal) with the face of the studs 110mm from existing wall with dense mineral wool infill and 2 layers of 15mm soundblock and there will be no thermal or sound issues. The regs give you lots of leaway as it is an existing wall and not exposed to outside. Metal stud would be my preference.

[Gooman]

13 hours ago, Mr Punter said:

You may be overthinking this.  Independent stud wall (95mm timber or 70mm metal) with the face of the studs 110mm from existing wall with dense mineral wool infill and 2 layers of 15mm soundblock and there will be no thermal or sound issues. The regs give you lots of leaway as it is an existing wall and not exposed to outside. Metal stud would be my preference.

 

That sounds a lot simpler.

 

Can you give more specifics on the cross section and the type of product? Do you mean 110mm of dense mineral wool? For example, 100mm Isover Acoustic Slab and two layers of Soundbloc only gives me a u-value of 0.319 (and that's not taking account of the 70mm metal stud, as I'm not sure how to add that in Changeplan).

 

The BCO has said that although the other side is not exposed to the outside, as it's an unheated non-integral garage it's regarded as an external wall and needs to achieve 0.3.

[Mr Punter]

If you want good acoustic insulation the dense mineral wool is better, if you want thermal the PIR wins.

 

You could stick some Celotex - say 30mm to the wall then a 10mm gap and 70mm metal stud with 2 layers of 15mm soundblock infilled with dense mineral wool.

 

I am not sure if this applies:

[Gooman]

I don't think that's going to fly with my BCO. He's insisting on a 10mm gap for acoustic reasons, and the thermal rating. 

 

I think I'm back to plan A :

 

10mm gap

50mm timber studs infilled with 50mm PIR

12mm PIR on top

25mm battens and mineral wool (plus cables in conduit)

15mm Soundbloc 

5mm plaster skim

 

I think that's the best I'm going to get. Unless nextdoor turn their garage into a major workshop working evenings and weekends, I don't see that I'm going to have a big noise problem.

 

Thanks everyone for all your suggestions and help!