Thorfun

planning wouldn't give us a bigger property above ground as it would've been substantially bigger than the existing property. so my 'fun' rooms had to go somewhere and so a basement it was. plus I've always wanted a basement. ?

@pocster speaks words of wisdom here. even if you can't do any of the labour yourself then you could save a lot of money by project managing the build and using subbies to do the work. could save at least 20% over using a main contractor.

+1 to this. we are having a basement built (just nearing the end of that) but it will end up being about 1/3 of the total cost of the build.

I moved it all to the garage quite a few weeks ago as well so it's now in the dark. hopefully it'll be ok.

thanks for the response. I thought that might be the case. I will double check with Wunda what the maximum UV exposure time is. it's still wrapped in their paper type packaging which might help I guess.

do you need a 'special' contractor? insulated foundation systems are very simple to lay so surely any decent groundworker can figure it out. as soon as you start looking for a 'specialist' the price goes up! maybe worth looking for a general groundworker who is recommended and ask them if they're happy to do it. if they can follow a drawing then I'm sure they'll do fine.

rather than doing that might it be better to go with your gut feeling and the 'chemistry' you have with one of them and give them the opportunity to come up with a few designs. if after that concept stage you don't really like what they've done then just explain it all and cut your loses and move on to another one. that way it saves you £10k and a whole lot of hassle with other design ideas fitting into the chosen ones as discussed above. but I think you'll find that if you've done your homework then your original chosen architect won't be a million miles away after initial concept sketches and even if you are then a few quick discussions with them and they'll come up with some changes. that happened with us, his first sketches weren't what we wanted at all. but after a quick meeting we discussed the bits we liked and didn't from each of the concepts and he came up with something we loved.

we chose the architect that we thought we'd be happy to work with after meeting them all. worked out great! portfolio and costs were also a consideration but I think the 'chemistry' that @Bitpipe was talking about is of paramount importance.

prepayment is normal unless you have an account. worse case scenario is he does a runner with the money but the cost of 10t of 6F2 isn't going to get him very far so I'd suggest it's a gamble worth taking. ?

openreach supplied all the ducting for running our new connection to the house. it's the grey stuff they use. have you tried contacting them?

+1 you don't need the 50mm ventilation gap if you have an air permeable membrane like Proctor Roofshield and can fully fill the rafters. but you do need to batten/counter batten above though. but make sure your BCO is ok with that. ours is.

this is our gable end. cost for the glazing (not including the front door and top light above) £4500. triple glazed alu-clad.

good luck. we've just finalised our schedule and will sign the contract this week ready for installation in October. they've been very good throughout the whole process and hopefully the delivery and installation will be just as good!

I've got the install guides for the Powerwall somewhere so will read up on the Gateway. all our PV panels are on Solaredge Optimisers due to shade. would that make the strings irrelevant? our PV is being designed by Enhabit who, iirc, who used as well? I'll also speak to them again about this whole subject.

all good points Dan. pretty sure we'll be taking 3-phases to main consumer unit, I see no reason not to. yeah, I've read about vector-sum metering before and it seems logical but as we're having a Powerwall I'd rather the generated power ALL went to the battery and then any excess is 'sold' back to the grid for a paltry amount. just seems more logical and more simple that way. I presume that if I wanted to change to a 3-phase Solar PV system in the future I could swap out the single-phase inverter for a 3-phase inverter? if so, think I'll just stick with the simple setup for now. obviously, if the DNO says no to the PV array size on the G99 then I'll go for a 3-phase inverter.

we've actually gone the other way (DNO approval pending) and have decided to run our 10.2kWp PV array via a single phase inverter even though we have a 3-phase electricity supply. we are running the house on a single phase and didn't want the other 2 phases from the PV inverter just being 'lost' to the grid when we can use it in the house. A 3-phase inverter would've meant only a 3rd of the generated electricity being usable most of the time. At the moment we don't drive enough in our EV to make a 3-phase charger necessary and so hardly any of the PV generated 3-phase electricity will be used. if we have a need for 3-phase in the future we can make changes then but for now just running a single phase throughout the house and with our PV systems seems logical. the 3-phase supply was a trivial amount more than a single phase connection so it was a no-brainer to future proof.

was also quoted £280 + VAT for a lorry load of recycled crushed from a company in Herstmonceux, but definitely shop around. there are deals out there although I found that recycled crushed depends on what they have at the time.

I paid less than £35 + VAT for type 3 virgin granite. not saying you need it as I agree than recycled crushed would probably suffice. but if you do want virgin type 3 then PM me and I'll give you the name of the company I used. but they are based in Kingston-Upon-Thames so shouldn't be hard to find if your Google skills are up to it. ?

we got quotes from a couple of different Internorm providers and they were very different. In the end we went for Norrsken and were very happy with their price and the quality of the windows/doors in their showroom. They also install with in-house installers so they're responsible for supply and install which means only one point of contact.

do you not need a second form of escape from a basement? I certainly did.

I hear and read that often on here and it's not that I don't believe the people who say it, it's more that it's hard to get my head around the concept of not needing heating! I guess it's a leap of faith (although I'm sure science could well be involved in doing the calculations try telling my brain that) but the voice in the back of my mind keeps saying 'what if it isn't?' and then maniacally laughs at me.

I have no cooling demand numbers sadly but I do have a very low overheating risk as we have external blinds. I'm looking for something as a just in case kind of thing. I was thinking of fan coils run off the ASHP but involves more ducting through the house whereas the pipework for a multi-split AC system is small. but, the flip side is the wall units for the split AC are large and the fan coil ducting opening is unobtrusive as far as I know. I will mention the fan coils to the M&E company. But I was also thinking that the split AC could be used as supplementary heating in the bedrooms if required and would negate the need to run UFH pipes. ps. hope you're in soon! was back in March that you were plastering iirc so you can't be too far away.

hey @Dan F. how are you finding the supplementary cooling via your MVHR system in this hot weather? is it doing the job? just about takes the edge off? or not very satisfying at all? I'm considering supplementary cooling and our M&E guys have suggested using Split AC rather than using the MVHR system. just wanted your opinion of it please.

if this was aimed at me I don't have a clue! but I'll be interested in the response and will try and store the answer for future reference.

we used a Civil engineer to design our drainage, driveway, culvert and new entrance to public highway. it wasn't cheap but we have detailed plans of pipe runs, falls, invert levels etc.