Iceverge

Very comprehensive. Not too many holes to pick really for me. Budget I'm spitballing will be about £500000 by the time you move in. I always like a shower + bedroom on the ground floor but I guess you've provisioned for a lift. Have you thought of solar PV? My mate put in 2 seperate dressing rooms from the master bed. I wish I'd thought of that. Especially with different waking times. Some of the details might be tricky to achieve passive levels of thermal bridging + airtightness as drawn. Run PHPP soon if you can. Your southern glazing looks like it might cause overheating despite the awning. I'm impressed with your "amateur" drawings. What did you use?

I'd avoid PIR in the roof if I could. Especially between timbers. Mineral wool, woodfiber or cellulose would be better. I went on a bit if a rant here. https://forum.buildhub.org.uk/topic/23894-u-value-for-solid-wall/?do=findComment&comment=369038

Hi @ADLIan Can you show me the part of BS5250 you're referring to please?

Easy. 2 of these. Property prices at £8000/m2 in London should justify the price. https://midsummerwholesale.co.uk/buy/sunamp-heat-batteries/sunamp-ehw-12

Tape is impossible to get it to stick to anything concrete related in my experience. We used airtight paint. First coat was very watered down, almost like a dust suppressant + primer. The second and third coats were neat. I bought my stuff from Philip in Prodomo in Tralee. He's a mine of knowledge too. https://www.prodomo.ie/online-shop/#!/Belgacoat-Brush-dark-5-liter-air-tight-paint/p/137351991/category=109789652

Every build project has disasters no matter how diligent or experienced you are. We've all employed people who've let us down in one way or another. It happens unfortunately, don't beat yourself up. Impossible for us to tell I'm afraid. Of course please make sure you are safe when bringing it up with him, maybe a phonecall is best. Don't expect him to be delighted but give the man a chance to hold his hands up and admit he got it wrong. I suspect the most likely scenario is that he will answer your call, probably be defensive and after you hang up you'll never hear from him again but you never know.

I've been looking for it. The old version has been superseded by the 2021 version but thats subsequently been withdrawn from the BSI store for some reason. Are you using the new version or the outdated one and do you have a link?

https://www.ubakus.com/en/r-value-calculator "HK33" will be EPS bonded bead in the material list.

Add a copper slate rivet?

I wouldn't put a vapour barrier in at this stage. 2 layers of impermeable materials in a structure is a recipe for decay. Moisture will get in. You have to make sure it can dry either to the inside or outside. The inside in your case. Having a brief look at UBAKUS you can put full mineral wool batts/roll between the rafters with no condensation risk. Then plasterboard with care to seal all penetrations. https://www.ubakus.com/en/r-value-calculator/

We did ours below the roof trusses at ceiling level. Then a service cavity and then plasterboard. We left a gap between the roof trusses and the top of the internal walls so we could run the membrane uninterrupted from external wall to external wall.

From experimentation I found the average temperature of my tank is 30 Deg when it's no longer providing 40 Deg water at the top. After that it's just calculating the total energy in a body of water before and after. Putting the two formulas equal to each other and cancelling. Mass X deltaT X specific heat capacity of water

Bad idea. Rotten roof territory. I seem to spend half my time on here telling people that this is a terrible plan. Out of interest where did you get the idea that it might be the way to go? It seems to be everywhere. What is your current roof build up, what level of performance are you hoping to achieve?

Impressive .Good luck. How do you intend to build the retaining wall in a low carbon fashion? Stone gabions, low CO2 cement?

Have you run this past your SE re snow loading?

Maybe I wasn't clear. I was only suggesting OP should consider water storage temperature before committing to a 250l tank. Our taps are at about 50deg (same method as @ProDave) We use about 300l of water at 40deg (baths+showers+handwashing etc) and about 20l at 50deg per day. I disregarded the lower volume and higher temperature water for simplicity in the formula. In our case we get 400l of shower water from our 300l cylinder stored at 70deg but if we stored it at 50deg we would only get 200l. Agreed. We have a direct 300l E7 cylinder. 10kWh per night or €365/annum for hot water (2 adults +2 kids). Here's the complex control system and tank. Cost about €700.

How did you come by this number? With low temperature heat sources like solar thermal in the shoulder seasons and ASHP (50 deg) you will need larger than your current LPG setup at 70deg, I think i’d go for the largest simplest cylinder you could fit. If you want something bespoke Newark cylinders are helpful.

https://www.cylinders2go.co.uk/shop/stainless-steel-unvented-cylinders/telford-tempest-300-litre-twin-coil-solar-and-heat-pump-unvented-cylinder/

welcome welcome. It’s difficult to get proper room sealed stoves outside germany and austria. Here’s one site. Search “dibt” room sealed air supply. https://www.kamdi24.de/kaminofen Remember you will need an excellent flue system also to get good airtightness. I was all set to go down this route but I couldn’t get good installers and good products for a reasonable price. I have little regrets about not bothering as we couldn’t have gotten as good an airtightness result with a stove.

I built my own silencer. worked very well. Next time i would combine and build my own manifold/silencer like @joe90 did. I would consider building a soundproof cupboard for the MVHR UNIT too. You can hear it when the door to the utility is open.

0.45 isn't too bad, especially in a terrace. Have you run done a run through PHPP or Jeremy's heat loss spreadsheet here ? It's pretty good and will give you a feel for the balance of varying U values. Concentrate on MVHR, airtightness and high performance windows and you'll be fine.

They're waiting to see how gas works out. Its probably still too early to tell.

It's too cheap and too easy. Couldn't possibly work .

You probably don’t want to hear this but i’d rip it out. Take the unused PIR back to the shop. Chuck any used offcuts into the loft. Buy some membranes and mineral wool and do it properly.

Gas was too cheap. Tradition of wet heating systems. No contribution to DHW. Costs start to stack up if you want to out one in every room ( in a well insulated house you don't BTW) COPs weren't always as good as now. People didn't know about them in a residential setting. If you look outside our fair isles they are extremely popular.