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Expanding on my thoughts. If you have ground that suitable for this solution and are happy with the performance then it's a valid option if it is cheaper/quicker/easier to install. But I suspect you can get the same performance from a traditional foundation with somewhat lower cost (can get any groundworker to do it vs a specialist) and the industry is just much more comfortable with the engineering of traditional slabs which may make other things (insurance, future sale, warranty, etc) easier.

I missed that before, sorry. Still not sure it really changes my view. Marmox blocks are good but they are still much lossier than the other mentioned solutions. There is also nothing stopping using marmox blocks with a traditional foundation and save all the custom eps/engineering costs (use it on the inner leaf and ensure the non-load bearing floor slab is thermally broken from the foundation).

@-rick- Thanks for your comment. Just checking, did you see the whole image? For some reason, after I uploaded it, I only see the whole image if I click on it and open it. Here it is uploaded a different way. Does that answer your question? They have a toe on the raft which the bricks sit on, but with a course of Marmox blocks.

That looks cool. Just need to find a suitable competent person willing to use it and sign which might be a problem. Having said that, in time this looks like a solution that will work once the competent people get familiar with it.

While SAP10.2 allows manufacturer data and fallback to default values that are 'tolerable', SAP10.3 and it's follow on Home Energy Model (HEM) essentially force the calculation of thermal bridge PSI values. Using the defaults may fail your whole property and manufacturer data is no longer allowed. Failing SAP10.3 would mean you do not get you completion certificate and not be able to occupy your house. I have deliberately chosen SAP10.3 as it certifies a higher thermal performance which to me translates to increased value in the house. However, getting the psi-values done has been a cost and professional involvement nightmare with one wanting between £5-8k for 12 junctions. Recently I came across a real alternative that would give you back control. It's easy to use and does not cost a fortune. The site is https://psiclops.io with plenty of verification links, the ability to use DXF drawings as well as layer definitions and it validates against BR497 and gives you a full report.

Should we consider BS 6297 as just a guide when applicable to England and Wales? There are conflicts - for example undisturbed ground between trenches. BS 6297 says 'equal to or greater than 1 metre'. Part H says 2 metres. That's a huge difference when it comes to designing drainage fields!

Storage yes massively important for building. Problem is you need the space you are building to be clear so you can build it. And you need to live in your existing space. We still live in chaos but by necessity have evolved a system of boxes/crates for stuff - the PPE box, the mastics and selants box, the small tools box, the large tools box, the rolls of tape box, the useful wood offcuts box, the electricals box, the smart home box, drawers with zipbags of stuff you need to find later, the 2.4m timbers corner, the cable reels cupboard, the box of sample leftovers pieces so you know what you bought 10 months ago should you need more of it etc etc etc.,

That's a pretty stonking great thermal bridge there. Not keen. Both AFT + Kore systems have thermally breaks between the inner and outer leaves. With that thermal bridge I'm not sure why you would bother with the extra cost of an insulated raft vs traditional foundations. What U value are they claiming?

I'm shopping around for foundations for a timber frame structure with brick outer leaf. I don't plan to do it myself but will engage a ground works company to do the install. I've not had a ground investigation yet, but indications are that I have good ground conditions, about 600 mm top soil with compacted gravel and sand below. I've had to dig holes and trenches down to about 1.2 m around the plot for various reasons, and never seen water. I'm most interested in speed of installation, simplicity and cost. Regarding energy efficiency my expectation is that whatever foundations I go for, they can be made be good enough. So I'm not wedded to any particular type of foundations and have been getting prices and talking to installers, suppliers and structural engineers to make my decision. I had been talking to AFT and an installer they had recommended, but as I mentioned in a previous post, AFT have ceased trading in the UK. The recommended installer is looking at carrying on his business with a different insulated form work supplier and is looking at Build Lite. I'd be interested in thoughts or comments on my approach but also on the Build Lite insulated raft system. I've attached their sketch from their website. Thanks

I really think you should call a few installers and see what info you get from a first chat. I don't know the amount of back and forth you've had with Gemini but I suspect it's only giving you a partial (at best) picture. There are planning permission issues with multiple heatpumps, 2 is the limit now I think so you might be ok but would need checking. Also worth checking that AC style units comply with the MCS noise limits. The water based monoblocs are generally all MCS compliant but AC units might not be as they are more often used commercially and if you want to use them for heat you need to make sure they are sized correctly for UK winters (some aren't). I suspect an AC installer would be able to install an overall AC system for a bit less than Gemini guesses. There is also a £2500 grant available for AC units similar to the Boiler Upgrade Scheme though I think less complicated (not sure how it's claimed). Still given you are planning to replace pretty much everything going to a water based system with fancoils is likely possible for a similar net price quoted above once the BUS grant is taken into account.

Forgot to put an update on this!!! It FAILED spectacularly. Building control refused to sign it off on many counts which was the only sensible outcome. P.S. for those who thought it was acceptable and those that are watching and still build like this, don’t come to Shropshire , substandard workmanship isn’t acceptable here 😎. For those that were helpful and constructive I thank you 🤠

Thank you all for your comments, I’m not a self build person really but got great project advice from this forum some years ago. I get that the first proposal is complex and expensive and I have an option B that Gemini has summarised below. I could keep my vented HWC but I’d like to remove the shower pump and cold water tank from the loft. I’d appreciate any further comment from the group Standalone Capital Project Cost Estimate By stripping away complex hybrid refrigeration-water networks and executing this clean, standalone Air-to-Air + Independent Slimline Direct Unvented Cylinder layout, your project total drops into an incredibly attractive budget bracket, remaining 100% eligible for the 0% VAT rate on the heat pump and cylinder elements: System 1 (Ground Floor A2A Multi-Split): 3 Midea Breezeless-E heads (Lounge, Sun Room, Kitchen): £1,900 – £2,300. System 2 (First Floor Loft Ducted + Playroom Head): Medium-static fan-coil + 4-zone motorized dampers + Playroom wall unit: £2,500 – £3,100. System 3 (Unvented Direct Cylinder Conversion): Supplying a 150L Slimline Direct tank, full gas boiler decommissioning, radiator removal, capping the gas mains, and removing the loft cold tank/shower pump: £2,200 – £2,900. System 4 (Bathroom Elements & Smart Towel Rails Fitted): £300 – £500. Boiler Resale Spare-Parts Credit (Private Cash Offset): -£80 to -£150. ESTIMATED NET CAPITAL OUT-OF-POCKET COST: £6,820 – £8,650 (No BUS Grant needed for this tier, keeping your capital outlay significantly lower than premium hybrid systems).

Not sure what risk they’re taking given there doesn’t appear to be any penalty?

Manager ? In reality I'm the resident labourer, and got fed up falling over stuff left behind by others. So the role evolved into - every day- clearing up after everyone else. Clearing up is a very necessary job: bit like oiling the cogs in a machine. Clearing up wet concrete has to be done at the time - but mostly you cant do that. So it needs planning for. @TerryE's suggestion saved my sanity. I would have blown a fuse if I'd been faced with @Spinny's ermmm, dump We have about half an acre, so a good few nooks and crannies . House is about 10 by 10m I think it was @TerryE who -years ago - suggested self builders make a storage plan - so I did. Very glad we did TBH.

There's no room around the outbuilding for the heat pump either unfortunately – we're building on the site of an old walled garden on a hillside, and have neighbouring properties on all sides. Outbuilding is about 45sqm total, although only 30sqm has UFH pipes in. (the remaining 15sqm has a cellar)

I will ask the question, thanks.

Do you need a drain to go in there for the cylinder ?

Don't worry, your builder will take good care of this issue... (It certainly won't be dumped on your drive and left for 3 months before a labourer breaks it up with a sledgehammer and SDS drill. 🤪

Which will enshittify the world even more. What amazes me about these scams is that the creators have a flair for marketing/advertising/promotion/sales, and then take a risk by selling total crap. They could use the exact same skills they have and sell viable goods, and probably at a higher markup. I used to work at one of the largest jewelry retailers in Europe. The markup was about 10 times the wholesale price. It is never worth stealing jewellery, you may, at best, get 20% of the wholesale value. Not really worth it.

FYI I called Ubbink UK and the salesperson said the Brink / Vigor units are exactly the same except for the branding. It suggests to me that a bunch of sellers in the UK are grey importing from Europe.

The EU are doing fine. They have been putting record fines on the tech companies for non-compliance with various rules. Not sure about advertising. But most of those rules we have too as they predate Brexit. The amount you can bring in in fines should easily pay for enforcement. The pre-existing EU derived rules have plenty of fines based on % of revenue/turnover (depending) and so does the Online Safety Act. EU court has just ruled that under existing rules the tech companies are liable for content on their platform so they can be sued if they host defamation, take part in fraud (false advertising), etc. Again those same rules should apply here. Basically this country should stop making excuses. The government has already shown it can force the tech companies to implement ID/age verification all over the place that in my view is a huge detriment to the open internet ('want to access this reddit post that might contain the answer to your tech issue, we need to create an account and verify your identity first'*). If they had put the same energy into forcing the companies to take responsibility for what's on their platforms the platforms would likely have got much more kid friendly, fraud would be down, etc. * We aren't quite there yet. AFAIK you need to verify ID to post but not to read, but with the under 16 ban I can't see how they implement that without every website like reddit being completely blocked until you create an account and verify ID. Even if you are ok with doing it for one site, if you are doing a search and you get 10 results and every webpage on the list requires an account and verification to proceed it becomes completely unusable. People will just ask AI instead (which creates a whole host of other problems).

Neighbour one side has a scaffold tower up and is busy replacing his rotten bargeboard. Neighbour t'other side has his builder son in slowly cladding the front and rear of their side extension. I sit in the middle working with my LVT flooring guy to complete a 1000 piece LVT jigsaw without a reference picture. Busy Street - roofer, floorer, builder.

I'm so disappointed he didn't buy one of these for each room I loved the advertised claims, then the test and finally the deconstruction of the unit The old adage is "if it looks too good to be true then it probably is" has never been more apt

Then you broke up the concrete for hardcore? I wish we could return the big bags and they were recycled. Or the material didn't turn to plastic dust if you try to reuse them.

I think the EU are becoming stronger on this. Not a lot of resources though.