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.

When you say "clumpy", is that foliage that's sprouting in clumps, of is the ground now uneven due to moles and ants etc. A brush-cutter will sort the foliage and after several cuts get the grass growing more evenly. If the ground is uneven, you will still need to clear/mulch as much foliage as possible, but the then either turnover the ground with a large rotovator or bring in new screened topsoil.

Definitely photos needed. If it's "just" brambles, clumps and saplings up to 1" diameter, get started by hiring yourself a ride-on brush-cutter for a weekend. Something like https://hertstools.co.uk/product/as-915-sherpa-2wd-ride-on-mower-hire/ If it's thick bramble and sloping ground then get an AWD version. ...and wear protective clothing if there are brambles and black-thorn etc. Oh, and wait for the area to dry out a little. These brush-cutters are really capable, I was shocked at how they went through saplings and brambles. If you are not in a rush I'd cut it 4 times over the next year to keep knocking back the saplings, and then start digging out the roots of things that won't give up and spraying any re-occurring weeds. How about the boundaries, is there over-grown hedging? Nope, it wouldn't cut through the foliage, and won't leave it suitable for re-seeding.

Dr. Rod Williams (Williams Energy Design): https://mango-projects.co.uk/2020/05/28/who-are-mango-projects-ltd/ https://passivhaus.uk/directory/williams-energy-design/ Rod helped me out on mine and was very good.

Not me either. I did look at it, but went with poured resin directly on the power-floated RC slab.

Yes, that is an ancillary use. You can't add a kitchen and bathroom to make it habitable, independent from the main dwelling.

Yep, should be. You'd be wise to collect evidence of it being your principle residence, ie. registered for Bank, NHS, Council Tax, Utilities at the appropriate address, at the correct times.

Married couples "only" get Private Residence Relief on CGT, on one property (unless you are Angela Rayner). So, depends what you plan to do with the second new-build in your wife's name. If you can apply PRR to the property in your name, any profit you make should be tax free, until Labour change the rules.

You'd need to apply for an S73, variation of conditions, and try to get that condition either removed or reduced from the original planning application. There is a push for LPA's to use Conditions less than they have done in the passed, and old conditions are getting easier to change, especially if they are unrequired today. But, to be successfully, you have to argue that in some way the condition fails to meet at least one of the following 6 tests: Necessary Relevant to planning Relevant to the development permitted Enforceable Precise Reasonable in all other respects Definitely one for a planning consultant. Search for S73 applications on the local planning portal, and try to find a consultant that has successfully achieved similar. It would be worth spending a few hours of time for someone to review the specifics of your planning condition and advise if you would likely be successful.

No, PD only covers use incidental to the main dwelling, which means the building can not be capable of being an independent living space. Normally, the Council will act on a complaint and then give the owner a chance to normalise the situation by submitting retrospective planning. If the planning then fails the building would need to be modified to something acceptable (or meets PD), or removed.

But, a house that has uncontrolled (natural) ventilation above 3m³/m².h@50Pa is deemed to have sufficient ventilation (when combined with trickle vents and wet room extractors). That leakage is unfiltered and without an option to recover energy from. Any additional ventilation brought in by an MVHR system is unrequired, so while it may be filtered and have 85% of the energy recovered from it, it is additional, unrequired ventilation and therefore adds to the energy losses and dust/pollen/pollutants (that make it through the filters) within the house. It's having better air tightness that stops the uncontrolled leakage of warm air and ingress of dust/pollen etc. and then provides the option of heat recovery and filtration.