Dreadnaught

I might add that my foundation build-up will be as follows. Bottom to top: Blinding Heave protection, 220 mm, such as "Heave Stopper" or "Jablite" or "Cellcore". The thickness of the layer is dependent on the physical characteristics of the clays. PIR insulation, 200mm (100 mm for the edge thickening ("ring beam") and ribs). Also to contain various water supply pipes. Reinforced concrete. 100 mm (200 mm for the edge thickening ("ring beam") and ribs). Also to contain under-floor heating pipes. Quite a thick set of foundations. The insulation is usually EPS but I was able to choose PIR to make the build-up thinner because the insulation is not load bearing. As I have learnt, PIR would probably support the weight just fine but it has not be characterised sufficiently well that an engineer would be willing to specify it if it were load bearing (or, more to the point, his liability insurance would be willing to insure it). PIR can be only used when not load bearing, at least at present.

I am having an insulated raft over shrinkable clay, albeit with screw piles. It is currently being designed for me by a specialist engineer in Ireland. Edited to add: oh, and I inherited a soil survey from the seller of the plot, and everyone concerned with the foundations has asked to see it.

Its an understandable question but, no, the tops of the screw piles, which are capped, are embedded in the concrete raft, so that the dwelling's weight is fully transmitted through the piles and does not bear upon the ground (and so the tree roots are happy). The issue of thermal bridging from the piles is occasionally raised. It is a marginal thermal bridge that can be taken into consideration in the overall thermal modelling. The piles can be sheathed with insulation for some of their depth if needed (not in my case).

Understandable concern but consider that the water pipes buried in the raft are continuous, no joins. I suspect and hope that the chance of a problem is remote. And attaching those pipes to the steel mesh when the raft is being constructed doesn't cost much. I have mains gas in the road in front of the plot and for a long time assumed that I would connect to it. But with the arrival of electricity tariffs with overnight electricity as low as 5p/kWh for a nighttime window, I have been persuaded that installing an ASHP is a better solution, especially for the long term.

It seems so long ago that these decisions were taken, I can barely remember now (!) Thinking back, I bought the plot with planning permission already in place (I subsequently resubmitted and changed it) but that already specified the screw piles, which were chosen principally for their minimal impact on the tree roots of the protected trees that neighbour the plot. I chose the insulated concrete raft after looking at the alternatives, such as beam-and-block or timber cassettes. I liked that a raft can be used as a form heat battery, with embedded underfloor heating within it; an approach used by some of the other members on this forum. And it of course gives a solid-feeling floor with no bounce or flex.

No, yours aren't screw piles from the sounds of it. With yours, they will drill a hole, remove the auger, and then fill the hole with a metal cage and concrete. With screw piles, the steel pile itself has a screw ending. It is torqued in to the ground and left there; no concrete involved. See picture below. For mine, above the screw piles I will have insulated reinforced concrete raft, 100mm thick, with 200mm edge "beam" and cross-ribs, all tied in with the screw piles. The insulation under the raft, which is often EPS, will for mine be PIR. It is all being designed for me by a specialist in Ireland.

Welcome to BuildHub Herbie! What type of piles are you going for? I will be using screw piles for my build in Cambridge (once restrictions are lifted).

Welcome Edward! Looking like you've good progress. I will be building soon-ish, as soon as the restrictions are lifted, in central Cambridge.

That looks really good! Congratulations on a job well done.

We have a storm drain nearby but still had to opt for a green roof to comply with our SUDS requirements. The requirements limited discharge in a bad storm to 2.8 l/s and prevented the first 5mm of any rain event entering the storm drain. I had to hire an engineer to do the discharge calculations to make the planners happy. Unlikely but could adding a green roof be part of a solution for you?

(Great use of photographs (from a drone, I assume) and diagrams in your post!)

Any pipes or cables coming back out from of the house, such as for approach lighting, outside tap, garden power point? In general, things attached to the house will probably come through the wall but things further beyond will often be in a duct.

Many thanks @Tony K, I've sent you a PM.

By the way, @Tony K this is what @LA3222 managed to achieve … Very impressive!

Why do you think that? Does the example of people like @LA3222 and @Triassic, among others, not inspire you? I have had quotes for the screw piles. And I have a quote for the raft from a timer-frame company that does a combined solution of raft and frame. My engineer is currently finalising my raft design (or at least will be when the frame design is finished) and I will then explore the best approach to building it. If I can find someone, I would much prefer to partner with someone who is more experienced than me with such things and build the raft with them as a team. And then hire a specialist team only for the concrete pour and power float.

I am on a similar journey, @Tony K. I too will be taking the advice of some of those on this site who have done it before us.

What is it that you can only get from BPC and not the other supplier? Can't the other supplier supply everything you need? What's the advantage of not splitting an order? I'd personally go for 160mm if you have the chance and the runs will fit. All else being equal, bigger ducting will perform better.

Oh that's interesting. If it is in a bedroom then that would be a supply vent. Do you not have any silencers at all on your install therefore? I am aware of the debate about having a second silencer on the return-side, but yours would be the first install I have come across without any silencers at all.

Welcome to BuildHub @Jeremy! I note that the Shropshire Hills and the north Cotswolds are both within 50 miles of U. of Birmingham. I for one would love to live in either of those locations.

I'm going for fibre-optic FTTP*, using a local fibre-only ISP and a Government Gigabit voucher. * fibre-to-the- premises/home.

I would expect them them to contain a larger compressors than a small under-counter larder fridge (which is what I have in mind). And as noise increases non-linearly with work, all else being equal I would assume that they would be noisier. Happy to be provided with enlightenment. Are there American-style fridges that are inaudible now? My experience of them in general, and the one in my present home, is that they are unpleasantly noisy. Perhaps I am out of date and they are being fitted with quieter compressors, upgraded insulation, and inverter drives these days; although perhaps these are costly additions.

Because the temperature difference it is required to achieve is much the greater.

Others I believe have contradicted the thought, but my view is that it is problematic to have freezer within a living space because of the noise of the compressor. My preferred arrangement is a larder fridge in the kitchen, much quieter, and for a full-size freezer to be relegated to a utility room.

Anyone see Building The Dream S9E05 in Devon, the revisit to Siddy Langley and her glass-blowing studio cum house? She mentioned getting volunteer labour in exchange for bed-and-board using a website. Does anyone know which website?

And here is an example of an applicant writing to the his local council with a deemed discharge notice in 2019: http://plan.scambs.gov.uk/swiftlg/MediaTemp/1154319-869034.pdf