IanR

"Thermal bridge free" is a common term used in low energy home design, but its use relies on the person reading/listening understand what the term means. It just means that the losses at junctions have been reduced to a level that they have no effect on the overall structure's heat loss and can therefore be considered as a continuation of the floor/wall/roof U Value. The PassivHaus threshold for "Thermal bridge free" is a PSi value of 0.01W/(mK). The PHPP thermal modelling package considers any thermal bridges with that Psi of 0.01W/(mK) or lower as not needing to be individually calculated into the building's overall heat loss. They obviously do still need calculating to show they are under 0.01W/(mK), but their heat loss does not then need to go forward to the total building heat loss calc.

To offer help here, we're going to need the junction sections, but if you didn't supply them to who was doing your SAP calcs, you probably don't need our help, you need your Architect to produce the construction drawings including junction sections. With regards your original question, do you need a professional "designer" costing around £2K. If that's just for the thermal bridging calcs, that's probably a bit high unless you have lot's of different, unique details in different areas of the build (which you drawings suggest you don't). But if the £2K is covering creating the Junction sections, and possible construction drawings, as well as doing the psi calcs, that's very cheap.

From your January post you were up to ground level, so can we assume you now have your timber frame up? Do you really have an issue or have you just not supplied sufficient info for thermal bridges to be calculated so worst case assumptions have been used. Can you post a labelled section through the offending thermal bridges. Did an Architect do the overall design? Added: re-reading your OP, is it possible he doesn't know how to calculate the psi values (hence you'll need a professional) and has just realised that the new SAP rules for cold bridging make using the default assumptions an almost definite fail.

Depends what you're measuring/comparing. Personally I'm comparing cost, performance, flexibility of system, ease of install. If performance is your main comparator, then all on this list below can achieve performance beyond PassivHaus (I believe), although maybe not all are PH Certified, and some will require specific super structure construction to fully avoid cold bridging. If you want a full package, Design, Supply and Install, then it's difficult to avoid the premium price that Insulated Rafts attract in the UK and most of packaged options in the list above will be similarly priced and that price will suggest that an insulated raft is more expensive than a traditional foundation system. It is better performing so most accept the additional cost. If your focus is very much on cost as well as performance, then there are two areas of an insulated raft system that can be targeted. Self install allows you to avoid paying a premium for the labour, concrete and steel. It's difficult to avoid a small premium for the EPS as I don't believe there's any EPS Suppliers in the UK that will sell the bespoke forms direct to a retail customer. They all appear to be locked into whichever system uses their product. ie. Springvale EPS for AFT foundations. You can also target the cost with an "optimised" raft, ie. one that is Engineered for the actual super structure that will be built upon it and not over-engineered with 250mm thick concrete and 3 layers of mesh when it's not required, as you end up spending twice as much on concrete and three times as much on steel as you need to. AFT prefer you to self-install and their rafts were optimised for reduced concrete and steel. They also have different options for different ground conditions, performance and different timber/ICF/masonry super-structure construction, so are/were no one trick pony. It was a while ago that I sourced my raft, and at the time only Tanner's system offered the same cost opportunities, although he didn't offer as many tailored solutions for non-Larsen truss construction. MBC's rafts are optimised and good performing when combined with their Larsen truss structure, but I found them inflexible and only available as a package at a premium price, so the customer doesn't benefit from the cost optimised design.

@lizzieuk1 Did you get your Raft installed?

Sounds like a managed close, so hopefully existing customers are safe. A real shame. I do believe they offered the best product in the UK, although a few others were close, and when Olof was in the UK more, they offered a very good Service (can't speak for more recent times).

My understanding is that is an splice CBT enclosure that should be able to take at least 12 connections (3 are used already). The double cable is probably the network feed loop coming from and going back to the overhead public cable. The yellow stripe cable is a single private connection to a building. It does mean it's more work for OpenReach to add an additional connection (since it is a splice enclosure, not pre-terminated), but should have capacity to add additional connections.

You only get the 7 year warranty with an approved install via an Approved Installer. Nibe are not catering for the DIY market Nibe has a modbus module that you can add-on. My Loxone communicates with SMO40 controlled via it.

Nibe are excellent, but expensive and they control their installers very well. I have an F2040 and it's never missed a beat in 9 years.

Yep, that's how mine worked. Plus recovery of 20%VAT on any materials you purchase directly, that aren't part of a supply and fit engagement.

Directly on to the Insulated Raft. At the time it was £75/m^2. If you follow the link to my post that -rick- posted, it's got the full info in there.

I can recommend the poured resin option. I also considered all the alternative options. Mines a two colour resin, in the style of a polished concrete finish and most people that visit ask if it is a polished concrete, even though it wasn't the intention to be an exact copy. Lot's of colour options and the different lacquer coats allow for matt, sheen or gloss finishes. I've been pleasantly surprised at how durable it is. It still cleans up (mostly) like new after 9 years and ours has a hard life. They can be re-top coated as well should it ever start to show the wear and tear or you want a different colour/finish.

Here's a reference for what I did on my cow-shed conversion. I built the studwork frame, foamed the steels and cut away any excess with a hand saw, then clad the studwork. If you clad first and try to fill the void with foam it will burst the cladding.

It's a job for a ride-on brush-cutter, a walk behind rotovator is unlikely to handle it and leave you a lot more work to do to get just grass growing.

Not sure how far this chap would travel, but he was very reasonable for me. John Dobson, Essex Mammal Surveys. (He does bats too) https://www.linkedin.com/in/john-dobson-1a7b315a/?originalSubdomain=uk Alternately, look for other surveys submitted for applications on your LPA portal and go with someone not to grand, that tends not to find anything that requires further investigation.