Replacement Flat Roof, Unheated Garage - Insulation / Building Control?

[ThreadLock]

Still weighing up options for renewing the flat roof on our (unheated) attached garage. It's felt, of unknown age, has no ceiling and no insulation whatsoever. Only used for storage, and has never had a car in it during our ownership!

I've now had a couple of roofers round for quotes. Both appear quite trustworthy, but neither has advised on the need to add insulation - either as a 'cold' or 'warm' roof.

Does this sound correct from a Building Regs point of view?

 

[robinbanks]

Doesn't seem like it forms part of the warm envelope of the house?

 

[ThreadLock]

Doesn't seem like it forms part of the warm envelope of the house?

I suppose it could be argued that heat is being lost through the common wall and out via the uninsulated garage roof?

Would it come down to the payback time for the additional cost of insulation?

 

[robinbanks]

Is the wall between the garage and the house insulated?

If no, insulate that rather than the garage roof (because then also to be effective one would have to spend considerably more insulating the garage walls, floor and draftproofing so as to make the garage part of the warm envelope of the house)

If yes, don't need to worry about insulating the garage roof

 

[ThreadLock]

Thanks, rb - the connecting wall is solid 9" brick (no cavity). The garage was, I think, built in the mid/late 70's and is of brick & block construction - with a miniscule cavity by modern standards!

As usual, I'm probably over-thinking things and should just take the roofers' advice. Things do seem to have changed recently regarding "Part L" requirements, but I'm not sure how they affect this job

 

[robinbanks]

I'd definitely be insulating the wall, for benefit of my gas bill; leave the garage a cold space unless you're planning extending into it