Converting and soundproofing a detached single skin garage?

[Deluks]

Are you saying this might be a cavity wall?
Maybe get back to us when you've got a better idea of the current wall construction.

 

[Booty67]

Are you saying this might be a cavity wall?
Maybe get back to us when you've got a better idea of the current wall construction.

No, I'm thinking this could be solid brick instead of single skin, although I cannot confirm.

 

[Notch7]

No, I'm thinking this could be solid brick instead of single skin, although I cannot confirm.

Single skin is solid brick, do you mean a double thickness wall?

Double thickness is highly unlikely for a single garage

If you have a picture of the garage, you can tell by the brick bond

 

[Booty67]

Single skin is solid brick, do you mean a double thickness wall?

Double thickness is highly unlikely for a single garage

If you have a picture of the garage, you can tell by the brick bond

Yes I'm thinking double thickness I believe, I'm going to drive pass and take a few photos and measure external width

 

[Booty67]

Just drove past, externally the width is 2.72m, internally 2.5m. I believe this is indeed single skin brick?

 

[Booty67]

How should I be doing the roof? Cold roof or warm roof? I'm more inclined to do a cold roof, tho I'm not 100% sure if this is the best idea? I'd also like to install a loft hatch for storage

 

[Deluks]

Well the roof is already there. No point in redoing it.
But you'd need to do a plasterboard ceiling tied in with your plasterboard walls to keep noise in.
That door though, is your weak spot.

 

[Booty67]

I'm trying to understand these u values stuff, all the online calculators I've seen I can't seem to get on with.
Does this look correct? I'm not including stud works, DPM, vapour etc in this

I'm hoping this would satisfy building regs. 50mm of rockwool in the studs + 52.5mm insulated plasterboard (40+12.5mm) + another layer of plasterboard

 

[Booty67]

Here's my U values for wall/floor/ceiling.

I'm hoping that as my ceiling and floor is better than minium required I can offset the amount I require on the walls, will have to speak to local auth.
My plan for the floor is floating floor, DPM + 100m celotex on top with some T&G boarding. The plan for the roof is 100mm loft roll between the ceiling jousts and 150mm on top of that on right angle. With some celotex backed plasterboard + another layer of plasterboard.

Does this sound all right?

 

[big-all]

my neighbour 5 years ago 100mm studs plasterboard 75mm rockwool air gap breathable membrane 12mm tag shiplap thought he had cracked it and could drum to his hearts content untill i walked about 1200mm from the back off structure talking normally and he could hear me clearly so beware a sounding board off plasterboard sheet material through timber onto planking completely bypasses sound insulation

 

[Booty67]

Just worked out the space I'll lose if I were to insulate my walls to the 0.18 u value required. Almost 25%... Hopefully they'll be fine with me only losing 16%

Building Regs Doc L says

"3. If meeting such a standard would reduce the internal floor area of the room bounded by the wall by more than 5%,
a lesser provision may be appropriate."

 

[Booty67]

So I think I finally have a plan for insulating my walls, ceiling and floor. Had to make my own U Value calculator as all these online ones suck.

I plan on using 75mm of RW3 rockwool in the walls and ceiling, with insulated plasterboard to prevent any cold bridging + Green Glue + Another layer of plasterboard. Hopefully an u value of 0.275 will be enough for building control. From their documentation, it should be.

Floor is a floating floor with 100mm of PIR + 22mm T&G Boarding.

The ceiling is just 100mm of RW3 rockwool in-between the joists, with 75mm on top of the joists going the other way. With celotex plasterboard + green glue + plasterboard same as the walls.

 

[Booty67]

Any advice on above much appreciated. And I've seen a few builders start with the floating floor first then the stud work into the floating floor. This doesn't make much sense to me, but should I be doing the floating floor first? Thanks

This is the way I was planning but could be totally wrong

DPM across floor and 100mm - 150mm up the sides
Wall studs, with 25mm-50mm gap from the wall and DPM on the wall side
100mm PIR on floor
Foam and tape
22mm boards on top - glued
75mm rockwool in between studs
100mm Rockwool in between roof joists + 75mm on top right angle
Vapour Barrier Wall + Ceiling - Taped/sealed
Plasterboards + Green Glue + Plastering
Skirting
Decorate