Insulating a garage roof

[taz777]

I have a part-integral garage with a flat-roof. The ceiling has broken plasterboard and all sorts of water wans waste pipes running at various angles across it (some of the water pipes supply the bathroom which is above the integral part of the garage).

What's the best way to insulate and fix a new ceiling in this garage?

 

[freddiemercurystwin]

You're talking about insulating the bit that's beneath the living accommodation above, not the outside bit? Or both? Or just the outside bit?

 

[taz777]

Just the bit below the house (the bathroom is directly above the integral bit).

 

[ajrobb]

If there are no electrics, I'd be tempted to stuff it with loft insulation to the full depth (not space blanket stuff). The open mineral wool will allow bathroom splashes and leaks to drain. Moisture resistant plasterboard might be less damaged by occasional leaks.

The garage ceiling under the house is a fire barrier. As such, I suspect the work is notifiable to your LABC. They might also be interested in the insulation as you are replacing an existing layer in a thermal element. They might ask you to secure the mineral wool with chicken wire netting above the plasterboard as that could increase the fire resistance.