Thorfun

welcome. there's loads of information on that subject on here. happy reading! ? I also found that Mark Brinkley's Housebuilder's Bible book was a very good place to start https://www.amazon.co.uk/Housebuilders-Bible-14-14th/dp/1916016812

sadly, SE England prices are very much similar to Central London.

doesn't a liquid screed surround the UFH pipes better as it 'flows' around and under them to fill all available gaps? I didn't think a sand and cement screed did this so it would/could leave pockets of air resulting in slightly poorer heat-up times for UFH? I could be talking b******s though. we're having a liquid screed in the basement for the ease of it all. 6m3 of Cemfloor is costing me £2200 all-in (based in the SE before @nod quotes his up'north prices ? ). seems very reasonable to me and I'm happy to pay for the quickness of install and drying. For the ground floor I'm still undecided as to which way to go and I guess I'm using the basement as a tester to see how the liquid screed works.

are you starting to get a feel for what's required for self-building and project managing? you pretty much need to have decided windows, blinds, cladding, insulation levels (determines wall thickness), ventilation system (in case MVHR ducting needs to pass through steels or glulams) and I'm sure there are more BEFORE your architect draws up the plans!! each blind manufacturer may have a slightly different requirement for their cassettes which will need to be factored in to the architects drawings and if you're going for an all-in-one solution with blinds and windows then you need to have decided on the window manufacturer as well. (one area that takes a lot of research and time to get quotes as there are a lot out there and, according to posts on here, prices vary for the same manufacturer depending on the job). everything is affected by everything else and it's only later down the line do you realise how much a decision has a knock-on effect on other parts. eg. we wanted external blinds and chose the Warema ones. They required at least 80mm from the external side of the timber frame to sit in to and so we had to have 2 x 47mm x 47mm timber battens for our vertical timber cladding. this added a lot of cost to the battening as we went for a standard 140mm TF. if we'd gone for the 300mm twin-wall TF I presume we wouldn't have needed such big battens, or even a 190mm TF walls then it would be the same. so the one decision to have external blinds added more that we thought at the time. not that we regret the decision it's just one of those things I've learnt as we progress through our self-build journey! each decision has many unforeseen effects. don't let me put you off though, it is a lot of fun and we're enjoying the experience a lot.

I'll let you know when they're installed. ? but they're on vertical rails so I don't expect there to be any issues https://www.warema.com/en/venetian-blinds/basic-external-venetian-blinds.html

something like this I believe https://www.toolstation.com/tooth-plate-connector/p44246?store=SE&utm_source=googleshopping&utm_medium=feed&utm_campaign=googleshoppingfeed&mkwid=_dc&pcrid=558033462390&pkw=&pmt=&gclid=EAIaIQobChMI08z1wKjF9QIVc4BQBh2JzAMnEAQYAiABEgK1n_D_BwE&gclsrc=aw.ds

this is similar to what we're doing but I was planning to run 3Ph from the kiosk to the plant room in the basement and then run the house off a single phase but run 3ph to the garage internally so we can install 3ph car chargers (one EV at the moment and will change the other car to EV at some point once the build has finished and we have some money again!). our garage is built on an insulated slab so we can't run cables underground to it any more. although I've not discussed this in detail with the electrician so it might not work that way!

but those joist hangers need nails. ?

I have those on my roof trusses and, afaik, they hold the joined timbers together. they have lots of spikes on the back and when two pieces of wood are put next to each other they bang one of those in and it holds them together. or summink like that. so, no nails required in those

seems a little pricey. have you tried another company who offer a different brand of ASHP? I always get 3 quotes for comparison but you don't mention if you have or not. also, you've not mentioned the size of heat pump you require/already have.

this is how ours have been designed to fit. the timber frame company created the window openings wider and taller to accommodate the additional timber above and to the sides and I fitted that after the TF was erected and before the windows were installed.

it's not finished yet! a balustrade will eventually be installed but I'm not even at first fix yet so things like that can wait. ? yes, the really old bungalow just at the end of the flat roof is the current house that will be demolished and become our garden. so view out over the neighbours house and woodlands beyond after that. plus ancient woodlands to the left of the roof. South facing as well so just setup perfectly for a bevvie or two on a summer's evening.

we have one too from our bedroom overlooking the flat wildflower roof. I love it already and can't wait to be sitting on it, drinking a beer and watching our existing house be demolished! may not get much use after that but who cares. looks great.

ours haven't been installed yet but we have made a pocket above the windows/sliders and they will fit recessed in there and the cladding will come down in front of them. should look very similar to @IanR's. We're getting Warema blinds

yes, except we're putting glass wool between the studs (Frametherm 32) and 80mm PIR inside the studs so we're not cutting PIR to fit between the studs. that's not something I'd ever want to do! also, with mineral wool you get better decrement delay and more sound attenuation so I like the hybrid approach. this surprises me as we have some large glazing and Norrsken could handle it without issues. so if your feature glazing is beyond their limit then you're in a whole other ball game to us! internal blinds will do little to keep out the solar gain as the heat has already entered the house. there are a few examples on here of folk who built to passive standards and regret not adding external blinds as part of the build and had to resort to films on the windows. if you plan the external blinds now you can hind them in the fabric of the building. Also, from reading other's experiences, overhangs only really help during the summer months when the sun is high. in the spring and autumn when the sun is lower they do little. there are those that also installed Sage glass and love it too. so if your budget extends to it then that might be the way to go. if you search the forum you'll find examples. this forum is a wealth of information and a veritable gold mine for learning from other peoples mistakes! read it all and you'll be more informed to make decisions....or your head will explode with all the different options.

agreed. with that sort of budget/build cost then spending another £1k to get a second architect/designer to go through some preliminary ideas would be worth it in my opinion. at the very least I'd be confident that I'd done due diligence.

massive amount of guts I'm sure! and the OP has said they've been at this for 7 months with the architect so it's hard to fathom the amount of guts it would take to start over. but, sometimes those hard decisions have to be made and it's, generally, for the best at the end of it all.

been through these discussions on this thread recently common consensus seems to be that 8mm expansion strip is all that's needed and it is what our screed company has asked for (just bought 125m of the 8mm x 150mm stuff from eBay). I thought the 25mm or thicker insulation upstand was to reduce thermal bridges? but you've got ICF, right? so there shouldn't be any of those. @Nickfromwales has also mentioned in the past (iirc) that even with the insulation upstand you'd still need the expansion strip. I do have a thousand things going around in my head though and so can't retain everything I read so I might be wrong. plus I'd hope the screed company know what they're doing!

We did very similar to @Bitpipe, he was, in fact, inspiration for a lot of my decisions. Our basement has cost us approx £1100/m2 and that has got us a large area for 'fun' rooms where our teenagers can go and be out of the way with their friends. that cost is just to build it though and doesn't include the fitting out costs. when you consider that in the SE England finished houses can go for approx £4000/m2 there is a massive uplift in value of the property by building underground when planning won't let you build above ground. it was quite an easy decision for us as our ground conditions meant that any foundations would've needed to go down 2m to the bedrock (we're on clay surrounded by ancient woodland) and so, although more cost, as we were going down 2m anyway I thought let's just dig it all out and build a basement that I've always wanted. Also, as has been said previously, you could reduce the size and bulk of the above ground structure and make it fit within the plot a bit more as you could put snug/cinema/study/gym etc all underground. I really like @ETC's sketches and look forward to seeing what @Iceverge comes up with. But, in saying all of that, I fully understand that you're very far down the line with this design and get that the thought of basically starting over again, when considering the time and costs you've already put in to it, is not very appealing. but read the comments above again. it's not just one person mentioning these things. you've got architects, architectural designers and other professionals and serial self-builders all saying the same thing. can they all be wrong? I remember watching an episode of 'Building the Dream' where Charlie went in and said the plans were all wrong and suggested they go back and redo the design and planning approval etc. the family were reluctant but they did in the end and said it was the best decision they'd made. sometimes we get so caught up in it all it takes someone on the sidelines to point things out and to help make those tough decisions. whatever you choose I wish you the best of luck and will follow your progress with interest.

but passivhaus principles are all about reducing heat loss through airtightness and insulation, those renewables you've listed are gravy on the top and the UFH is a byproduct of having a well insulated and airtight house. I think that what we'd really like to know is how you plan to build the superstructure and what details you're planning to achieve the passivhaus levels of build? you've already stated that it's going to be timber frame but are you planning passive house walls (300mm blown cellulose) or a standard closed-panel system, or an open-panel timber frame and fitting the insulation yourselves, which is what we've done, or even a SIPS build. knowing this will allow you to focus in on who to approach for quotes as some TF manufacturers don't offer some solutions. we chose the open-panel TF due to costs but if I hadn't built the basement then the money I would've saved would've gone on a 300mm blown cellulose wall structure but we couldn't afford that with the house that we designed with the basement included. also adding insulation yourself is not something to be taken lightly! I have saved thousands doing it ourselves but I am already pretty sick of the sight of insulation and I haven't even started on the internal PIR boards over the studs. For windows/doors we bought Norrsken and the fitters they got for me were excellent. Windows are very good quality 3g and were delivered on time and I couldn't fault the lads installing them. I can very highly recommend Norrsken and am a very happy customer. this is the approach we took and it has worked well so far. don't underestimate the time and energy project managing takes though. your brain will be swirling with the 100s of decisions you have to make and sourcing materials to ensure they're on-site at the right time for the trades to do the work etc. There are many blogs on here which will give you great insight in to the whole process. I highly recommend you read through them. mere babies. ? best of luck with it all, looks like a great project and we look forward to reading about your progress.

no, it's really not that bad at all down there. and it won't get wet again as all our windows and doors are in now so if we get any more water in the basement then we've got big problems!

thanks. so that makes me feel a bit better about running heater and dehumidifier on one extension during work hours. will turn the heater off overnight though.

definitely not groundwater! it's more just a case of rain getting in to the building and through the block and beam before we put the windows and doors in. and it's cold down there (about 6°C) and so I just wanted to warm it up and get it dry. I looked at the dehumidifier sticker and they're a bit cheeky with their 20l/day. that's at 30°C/80% humidity! it's 10l/day at 27°C/60%. so at 6°/90% I'm probably not getting much water out at all. which is confirmed by how little I'm having to empty the tray. ? I'll stick with my current plan though and I will get it dry.

that is a damn good idea! I will speak to my sparky about this. I think we're still about 4 - 6 weeks away from starting 1st fix, the bloody insulating is taking me bloody ages. ?

yeah. I saw this thread. devastating. we live on site in the existing property so there is always a sense of over-confidence as we're always here if things go wrong. but even living on-site wouldn't really help if a fire like that breaks out.