Dreadnaught

In my case, I found that the local structural engineering firm had one (relatively junior) engineer in the firm who specialised in SUDS and was able to do my SUDS designs and calculations that satisfied the planners. A general mid-sized engineering firm near you might have the same. As it turned out, using them was one of the biggest mistakes so far with my build, not because of their work but because of their approach and attitude, but that's quite another story. Also, I don't think its relevant for you, but in my case I subsequently learnt that the manufacturer of the system I was intending to use (in my case a green roof) would happily provide SUDS designs and calculations free-of-charge (so long as I also bought their products) and I wish I had used them from the start.

Zero missing? "OPTIM-R E panels achieve a declared thermal conductivity of 0.009 W/m·K", source.

@anonfool77, welcome to the forum. I can't offer any advice but thanks for sharing that list. I will be looking into getting one of these warranties for my forthcoming build (even while knowing that they are all quite useless). And your list is a good starting point for me. Good luck finding a solution for your problem. Personally, I would be tempted to ask the seller to arrange a retrospective warranty so that the sale can go through.

I am about a month behind the schedule in my mind. My signing-up with a timber-frame company was delayed as my favoured company moved their factory over Christmas. In the end I seriously considered no less than seven frame companies, met with five, and visited the factories of four. I have now chosen the company and will be signing on the dotted line soon. It is a local Cambridgeshire firm and represented for me the best balance between cost, their approach, and the personalities involved. Observations from the last month: Old Buildhub searches work well. I have text shortcut the throws the following in to a google search: "site:buildhub.org.uk". That enables effortless searching of the Buildhub archive for any string. For example, when thinking about which SE to use to design my slab, I threw "site:buildhub.org.uk Tanner" into Google a re-read the posts by @Alexphd1, @Triassic, @RichC and others, some of which were years old, arranged a call with Hilliard himself in Ireland, and all my problems went away. Same applied for bolstering my list of raft installers and a host of other subjects besides. I looked again at the make-up of my roof and foundations. My dwelling has a ridge height limit in its deeds and I want high, 3m, ceilings. I went around the houses on both subjects (thanks to you all for your contributions to my threads on the subjects). On the roof I ended up somewhere new, and flipped form a cold to a warm room, and saved about 200mm. On the floor, I ended up back where I started, with an insulated concrete raft attached to screw piles but, with the help of Hilliard Tanner, it will be a thinner 100mm raft, with strengthening ribs, and a 200mm ring beam. Because the raft will be tied-in to the screw piles the insulation beneath will not be load bearing. This means that PIR will work just as well as EPS as insulation. PIR is thinner for a given U-value so once again I will be saving about 200mm of thickness. Resolving the issues the ridge and front-door-threshold heights then enabled me dive deeply in to the levels. I have a small but complex plot and deciding levels took quite some head-scratching, especially as my site is supposedly "no-dig" because of previous tree roots. Levels are now done I think. With all the fundamental decisions about the build now resolved, the cavalcade of actions leading up to the start on site can now begin in earnest: frame design, engineering inputs, construction drawings; planning-conditions discharge (and maybe non-material amendment); tenders for groundworkers, screw-pile suppliers and installers, raft makers, rooflights, windows; site insurance, building control, warranty. Oh, and I have re-designed the façade once again. All systems go! Spirits are high.

Thanks @Dan Feist. Are you intending to buy one yourself? I wonder, how does one read "A+7/W35kW"; I am guessing "A" is air temperature and "W" is water temperature? I am following this closely as this as potentially ideal solution for my forthcoming build, combined with a SunAmp. Interestingly, R290 seems to be simply just propane gas (!) (CH3CH2CH3) but it has a desirably "low Global Warming Potential". I believe that a qualified and therefore expensive gas-fitter is not required for installation.

Did it. Skipped lots of the questions. It all helps, hopefully.

Welcome @Dpirie76. Suffolk is a beautiful county. I'm just across the border in Cambridge. I don't know any other Suffolk-based members on here but there are few of us in neighbouring counties.

Welcome. You're just south of me, I'm in Cambridge.

An impressive piece of draftsmanship!

@Nickfromwales: https://www.imore.com/best-homekit-humidity-sensors

I have embraced the Philips Hue smart lighting, especially the "white ambient" bulbs. Pricey I know but the "temperature" of the white light is tuneable.

Thanks @Archer. I hadn't seen Quickbase. Had a quick look. Says "lightweight foundation system for conservatories and lightweight structures". I will drop them a line to see what "lightweight" means.

Thanks @Archer. By coincidence yes I did notice that system this very weekend when doing some google searching. Yesterday, I sent them an email enquiring for more details.

Thanks @dpmiller, that's useful information. Another option for me to consider. Very good.

Not a great deal of help for you but I would counsel to choose a solicitor experienced in land conveyancing, not just houses. Its quite a different specialism.

I can't think why not. A steel ridge beam superficially sounds like a splendid idea. I will investigate.

Interesting. Is concrete board the same as cement fibre board? What type of insulation did you use? Were the joists timber I-beams? VPL, is that a VCL?

Thanks @ProDave. Makes sense.

Ah I see. Thanks @ProDave. Would the final floor covering need to be structural? LVT would not work?

Ah, I'm slow on the uptake. So a 1:8-biscuit-mix screed does not form the final floor surface. It is battened out and a final floor surface (e.g. Egger Protect) is added above it. [Bottom] Deck 1 → Joists (filled with insulation) → Deck 2→ Battens, biscuit screed & UFH pipes → Deck 3 [Top] Is that right?

Thanks @PeterW. Interesting suggestion. Will explore. One question: why "Add 25mm battens / timbers", what are they for? (Its a ground floor.)

Thanks ProDave. Very helpful information.

Now that's an unexpected suggestion, worth exploring! Thank you. Supported on the screw piles? How to insulate, PIR insulation above somehow?

Thanks @ProDave, as always. Good thoughts. Why do you have a timber floor downstairs? Do you get much underfoot flex? Do you have a screed? I am wondering if that would change how it feels.

Max span is about 5.8 metres. If that span was problematic, I presume it would be quite straight forward to specify an extra screw pile or two. Yes screw piles. The floor will have no direct contact with the ground surface. Yes, I presume so.