Redbeard

OP, forgive me if I have missed this, but where do you see the mould and condensation? Is it on the main frame members (perhaps the bottom of the uprights and on all of the horizontal members) or perhaps only at the very bottom of the bottom members? The former could suggest that the specific frame sections are much less well-insulated than many of us thought* and the latter that it's perhaps the cold floor cooling the frame and taking it below the dew-point, in which case replacing the course of bricks immediately below the cill with Compacfoam could arguably warm things up enough to address (I hesitate to say 'cure' as we do not know enough about the specifics) the worst 'manifestations'. *Do they still use galv steel reinforcement at the corners of bigger frames?

@fandyman sounds like a 'bowing-out' post. I was about to trawl back for/ask for further details of the condensation/cold, and exactly how it was manifesting. I thought I had read more of cold spots than of condensation of mould, but I may have skipped past a significant bit. If you're bowing out I won't trawl back/ask my Qs (which would have included what the issues were with condensation and mould on the old door. Edit: I think maybe you did not have a door there at all, as you had a conservatory.). Is the condensation forming on the frame and running down onto the screed, or forming on the screed, *not* on the uPVC? The more detail you can give the more help we can be. I wish you luck with it, whether you pursue it here or by other means.

I think the points being made by those who have responded to your OP suggest that, however regrettable it is, most window/door re-fitters do 'fit the hole'. In the absence of any other instruction (such as re thermal bridging mitigation, which might be included on an architect's or other professional's spec.) that's 'what they do'. If they have not 'fitted the hole' very well (the sealant is poorly-detailed or the opening lights do not 'kiss' the draught-stripping well) this can and should be amended. Then they would have done the job 'with reasonable care and skill', 'fit for purpose' (it's a door without draughts) and 'as described' insofar as their 'offer' probably said something along the lines of 'supply and fit XYZ door'. (What did it say?) If peripheral insulation measures had been promised and not installed then the CRA (of which I know nothing, TBH) may 'kick in'. Knowing that you are unhappy about the cold threshold I suggested a careful and painstaking 'stitching' job with Compacfoam or similar. That could be done (with caution - don't accidentally introduce 'droops' as others have said) but it would be an extra over and above (as far as we know) what was quoted for.

Deleted: Edit: I had not read @RedRhino's post above, so I had just effectively repeated their theme. Sorry!

Answers: 1. I doubt if any of us here would say it was acceptable but I suspect it is common. 2. Yes for me, and I guess for all of us here. 3. Not much, and yes. 4. I don't know. I fear that there's no obligation to insulate below a cill. I'd do it anyway, but whether Bldg Regs would *make* me do it, I think perhaps not, but not certain. The last patio doors I was involved with were sat on Compacfoam. 5. No, sorry. I think if I had been presented with what you have there I would be cutting out a brick at a time and replacing with something like Compacfoam - expensive but effective load-bearing polystyrene. I am sure there are lots of really good uPVC window and door installations. Unfortunately I have seen a large number of average-to-awful ones, so this detail upsets me but does not surprise me. Was the uPVC door a replacement of an existing door, or is that a 'dropped' window opening? The latter, I think, given the odd cuts on the bottom half, RHS. Edit: Thinking about it, the patio doors we did were in a wall with EWI, so the compacfoam was 'buried'. In your case you'd have a 'raw edge'. It's late, so I'll think in the morning how one might deal with that. How far above ground level is the external cill? If it is close you'll get a lot of splash-up. OK, it's not a timber door, but neither is it ideal. (And whatever the Building Regs say, rain splashed up more than 150mm in many areas!

Oh I do like the potato connector idea!

?1 or 2 IBCs, cut out as necessary.

Ah! Thank you! It did, however, get me digging for relative weights of alu vs timber frames, and I could find no general authoritative source. AI, however (which I don't rush to believe generally but which may be right in this case) suggests that alu and timber frames (the alu being hollow and the timber not until the CFBs get in!) are similar in weight. So I ask the OP, or anyone, where does the 350 - 450kg come from for a 4m2 window?

Thanks for that?! At least it encouraged me to check the relative weights of alu vs timber. From motorcycling days I always thought of alu as very light, but then I never rode a wooden motorcycle...Rest assured that I never have installed alu windows and do not intend to, so all is well from that point of view!

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.

Variegated crushed stone, with a path area laid lower as a base for recycled block paviours. (Our contractor got approx 12m2 for free via Facebook when we needed to match in with some that I had laid 30 years before). That way you get a clean path and a solid (if perhaps sticky-in-the-wet - though I am sure that a better knowledge of stone than mine might also sort that one) hard-standing. If you have the space, 2 paths give clean vehicle egress for both sides of the car.