Building regs on old extension

Doozergirl

FreeBear said:

Doozergirl said: I've never had the conversation the other way around where the existing building is considered to let the extension down.  We know already that older houses don't meet current regs - it's the extension that needs to meet them, not the house.  The house could have zero insulation and still

be fine to be opened up into a compliant extension.

It might be possible that Building Control suggests improving the insulation levels of the walls in the old extension. If it is practical to do so without incurring huge costs, adding extra insulation is worthwhile. Depending on wall construction, 65mm of insulated plasterboard could well satisfy BC.

That said, ignore what the extension company says. Let BC guide you - It is unlikely that they will want additional work done on the existing structure or even be interested in it.

I agree with you.   Having read back over the OP and looked at the picture, the OP wants to upgrade the roof anyway, which will have to match current regs and improve insulation in other areas.   I think Building Control will be delighted about that.   They will not be worried about the foundations - the work is clearly historic and I've never known them to be concerned with foundations in any kind of conversion in 20 years - outbuildings, barns into dwellings even.  They're certainly not going to complain about the OP upgrading insulation. 

OP, I don't think you should be compromising here in what you want based on one person's opinion who probably doesn't want to do the work.  

Your intentions are good, you want to do the only thing they might ask of you and a chat with an approved inspector about your plans would make you feel better.  I think even LABC would be perfectly fine about it, but an approved inspector will negotiate with you on the upgrades.  

I would be building all of that with one roof, extension included. It will look far, far better as one entity and be less prone to leaks if it is just one roof.