Redbeard

A question: ''350 - 450kg?'' I have just looked at the order conf for one of my windows - 3G timber approx 2.3m2 - weighs 82kg. Yours are nearly double the area, so say double that weight - 164kg. I find it hard to understand what gives you the extra 190-290kg. Or have I misread the Q?

Could you perhaps build them in plywood boxes like some do for EWI and fix back to both brick and block? In EWI the EWI would form the reveal, but in your case perhaps you could tape in airtight and waterproof tape over the ply 'end-grain' and cover that end-grain and tape with, say, 25/ 32mm scotia moulding?

Sorry, did not spot this till now. I kept the OSB - it was anti-racking, too, and stapled the Intello directly to it. A/T tape over each staple...

Exactly what I had in mind for my post-and-beam extn, but at a late stage the variability in quality of OSB in terms of air-tightness made me think again. I used Pro Clima Intello and taped all joints and perimeters to an obsessive degree.

Copper. My roof is about 135 years old. I reckon 70+% is 'as laid' and has the original copper nails. No membrane, of course, and no leaks at present.

Add a good margin for error to the cited turn-round time. My last big-ish order was estimated at 8 weeks and took just under 14.

I assume you mean 'remove the need for conventional deep strip foundations...'. Even with steels you still need foundations - just fewer of them, insofar as you only need a footing where a post hits the ground (probably - ish). - Installation of new structural beam supports with associated foundations as required There are, at very least, 2 bits you need the SE for, I'd say: 1. To tell you how you make the pool 'stand up' while you almost undermine it with your footings and 2. To tell you what you need to make your extension stand up. Oh, and 3. You need his/her PI insurance....

Welcome!

Maybe. I cannot see a side path, but maybe there is, on the RHS. Can you get down there all the stuff you need? If it is a narrow path then there may be a lot of double-handling; for example pallets of bricks need to be stored at front and barrowed in small loads. Etc. etc x lots. You need an SE to design footings which will 'cut the mustard' with the least possible digging and impact on the pool. @Gus Potter may be along later. What is the green bit next to the proposed ext'n? Is it a hard-standing or the roof of something else? A lot may depend on whether you are having this wholly built by mainstream builders, or you are having significant input yourself. One person's 'fiddly' is another's 'joy of detailing'. And again, in terms of cost reduction, if you are providing say 75% of the labour after footings, and you are good with blocks, then building in block may be the answer. If you are good with wood, then TF... etc. So, is this a 'contractor job' or are you getting your hands dirty? The more detail you can give re 'variables' the more informed an answer we can give. I am visualising v deep footings next to the pool (ooh err!) but I am not a Structural Engineer.

Do you want more than you can get with PD? PD limits ridge height to 4m (from ground). We have a sloping site which 'lost' us c700 of that, so it would have ended up with a shallow-pitched roof which looked really stupid. Went with Planning and there was no issue except the wait. But we did not have the tree issue. If you can build what you want under PD why not do it. If you want to dot all i's and cross all t's you might go for a Certificate of Lawful Development as irrevocable (I think!) proof of PD.

Perhaps if your introductory mail had made reference to a range of apparently different surfaces of apparently different ages we might have suggested more than one sample, but the impression I, at least, got, was that it was the same original material throughout, in which case one sample is surely enough.

Send them a quote on letter-headed 'paper' to supply one to them at the price you have been quoted + 20 to 25%, and confirm it *will* be at the address before their contractor arrives.😉

Very true, but a lot of authorities used it as a 'short cut'.

+1 re no gas, although of course you can have no idea of how much you will save till you get a quote. Ditto agree with @Bonner re negotiating.

Dehumidifiers will do the job if the 'box' (the house) is closed. If it's not you will be trying to dehumidify the world (and that will take a long time!). If my guess re floor level is right and that residual cavity at the bottom of Pic 1 remains open you will have a sizeable thermal bridge all around the perimeter of the house at floor level. I find it hard to imagine the intention was to leave the lower cavity open, so what was the original plan for it? @Oz07 is right, I think, that injected bonded graphite EPS beads are your only option now (and the right option, compared with Rockwool which may absorb moisture, below DPC). I have had difficulty getting EPS blowers to engage with partial jobs or 'non-standard' installations, so I hope you have better luck in your area. For such a relatively small area, but one which it is essential to 'treat' with insulation, I think whatever you have to pay is worth it. I don't have any contacts in the SE, I am afraid. I am sorry you have had a difficult time of it.