Hi,
I'm soon to embark on a single storey rear extension project, which is essentially upgrading an existing ~40m2 extension that's been added to and upgraded several times since it was built some 50 years ago (none of them by me). Original drawings depict a single uninsulated slab 150mm (no screed), probably around 30m2. Patchwork of new sections added to date, may be insulated I guess but difficult to know.
Plan is to extend out a bit and sideways a bit, new warm flat roof meaning a new L shaped slab to go to a total of about 55m2. Highly glazed so U values already a potential issue.
Regs submitted and approved, detailing new insulated slab but not specifically stating whether this applies only to the new section or the whole area - thoughts being that we could negotiate with BC to put some minimal insulation on the existing slab rather than digging the whole lot up. Wet UFH intended (using thin panels designed for retrofit).
A few opinions on our chances would be appreciated from you guys with knowledge!
1) Regs have something of a get-out in that it states the U values are the target and 'where it is not practical or cost effective to do so, do the best possible' or words to that effect. Do BC tend to actually apply such leeway here? I don't think it's practical to excavate such a large area 'just' to make it pass on U values - personally I'd rather pay a few £100 more gas a year than many thousands now to dig up and re-lay a seemingly serviceable slab. (Obviously if budget allowed I'd love to have it all up and start afresh, but cost is a challenge already.)
2) If we do have to remove it, any idea how much money we're talking about to get a contractor in (SE England) and how could it be done without shaking the rest of the bungalow to bits? From what I've seen of it it's not the strongest mix but the sheer size of it is daunting. Access for a smallish machine and removal of waste not an issue.
Cheers - I have more questions brewing but this is the one that's the biggest unknown at the moment
I'm soon to embark on a single storey rear extension project, which is essentially upgrading an existing ~40m2 extension that's been added to and upgraded several times since it was built some 50 years ago (none of them by me). Original drawings depict a single uninsulated slab 150mm (no screed), probably around 30m2. Patchwork of new sections added to date, may be insulated I guess but difficult to know.
Plan is to extend out a bit and sideways a bit, new warm flat roof meaning a new L shaped slab to go to a total of about 55m2. Highly glazed so U values already a potential issue.
Regs submitted and approved, detailing new insulated slab but not specifically stating whether this applies only to the new section or the whole area - thoughts being that we could negotiate with BC to put some minimal insulation on the existing slab rather than digging the whole lot up. Wet UFH intended (using thin panels designed for retrofit).
A few opinions on our chances would be appreciated from you guys with knowledge!
1) Regs have something of a get-out in that it states the U values are the target and 'where it is not practical or cost effective to do so, do the best possible' or words to that effect. Do BC tend to actually apply such leeway here? I don't think it's practical to excavate such a large area 'just' to make it pass on U values - personally I'd rather pay a few £100 more gas a year than many thousands now to dig up and re-lay a seemingly serviceable slab. (Obviously if budget allowed I'd love to have it all up and start afresh, but cost is a challenge already.)
2) If we do have to remove it, any idea how much money we're talking about to get a contractor in (SE England) and how could it be done without shaking the rest of the bungalow to bits? From what I've seen of it it's not the strongest mix but the sheer size of it is daunting. Access for a smallish machine and removal of waste not an issue.
Cheers - I have more questions brewing but this is the one that's the biggest unknown at the moment
