Thorfun

Thank you so much. I’ll go through it once GBBO is finished!

good catch. yes, the architect has specified 30mm PIR above the internal waterproofing system. I'm not 100% sure why but maybe something to do with not being able to or maybe not wise to screed directly on top of the waterproofing membrane. or maybe he just took it from this drawing supplied by the waterproofing contractor. either way, I'm actually ok with the extra 30mm PIR. The screed is because of the waterproofing membrane. we can't put UFH pipes in to the slab due to the fact as well, so we need something to go under the finished flooring to house the UFH. we could use 30mm PIR on the walls but that will reduce the room size and so maybe adding extra EPS outside the walls would be the best way to go. thanks for the responses so far. definitely giving me food for thought.

welcome. you're right, there's loads of folk on here that know what they're talking about. one day I hope one of those will be me! ? our architect charged us £2k +VAT to get us through planning (in SE England) so £5k seems a bit steep to me. good luck.

the architects have already been in contact with KORE (albeit a chap called Steven) and we are awaiting a response from them. I just wanted to put it out to those on here who also know what they're talking about. ? the 0.10W/m2K target is overall floor U-value for EPC/SAP calculations really. tbh, I plucked the figure out of the air based on the MBC passive slab. it seemed like a good target to get to at the time as I was (and still am) pretty ignorant of the whole thing. same with the walls. 0.12W/m2K seemed like a good figure and the as-designed SAP reflects those target values. Once I actually get the house built and budget becomes a factor I have the option of reducing the wall insulation a bit which will give a 0.14 or 0.15W/m2K figure and then the as-built SAP will change. but for now I just want to get the BR drawings finalised so I can get the submitted and crack on! it seems that the SE is awaiting the final thickness of EPS required to get the U-values I requested of the architects. probably should've done this all sooner but you know how it is. ? did that add a huge amount to the overall cost or was it pretty negligible?

Hi @Edward. thanks for the response. I think the architect is already asking Kore about the calculations but this forum has already given so much great advice that I thought I'd seek out the thoughts of the collective hive mind. I'm aware that there are other companies that will offer the insulated foundations and I will approach them for quotes but this is simply for the building regulations drawings and as-designed EPS/SAP. I did ask about needing EPS300 and some of the point loads on our building are high enough to require EPS300 (I'm not going to argue with the structural engineer on this point as I trust their calculations and I am in no way qualified to do it myself) and to avoid confusion where EPS200 could be specified and run the risk of getting the wrong spec in the wrong place they have specified EPS300 throughout. I'm ok with this and would rather it was over engineered than run the risk of issues in the future. Again, on the second drawing I am not going to second guess the structural engineers and believe they have designed the foundations to deal with any heave. the company, TSD, are insulated slab experts and so I trust them.

so, I've put what I think is correct into change plan and got the following for the basement floor and walls. do they seem correct? if so, I'm happy with the floor but the walls aren't quite near to the above ground u-values of 0.12W/m2K. I'm thinking that I really shouldn't be worried about hitting 0.12W/m2K in the basement walls as to get that level I'd need 300mm EPS which seems excessive for a basement, especially when airtightness seems to have a much bigger impact on heat loss. thoughts?

thought I'd better add the spec sheets for the Kore EPS ?‍♂️ Declaration_of_Performance_KORE_Floor_EPS_100_White.pdf Declaration_of_Performance_KORE_Floor_EPS_300_White.pdf

Hi all, I'm after a little bit of help calculating the U-values for these proposed foundations using the Kore system. this one is 200mm of EPS300 under the basement and up the walls: and this is an example of what's under the rest of the house where there isn't a basement. this is a TSD designed Kore system with 300mm thick EPS which is very similar to the MBC passive slab so I would presume that this will yield a U-value of 0.105W/m2K as stated on the MBC website? our architects need to know the thickness of insulation we'll need to achieve 0.10W/m2K on the slab and 0.12W/m2K on the walls and I'm hoping that someone would be able to assist with what these current drawings would yield for U-values. I do use https://www.changeplan.co.uk/u_value_calculator.php to do my normal U-value calculations but I can't see anywhere on there that would take in to consideration the soil at the depth of the basement slab nor what effect the soil has on the basement wall U-value. can anyone assist please?

or potentially use the Helm tracks that @Onoff mentioned in the thread I linked above if the wall size is sufficient and it's the look they're after.

I'm with @Mandana on this one and wouldn't be looking at pocket doors. from the looks of the plans the pocket wouldn't hold much of the door (assuming a single track pocket door) and bifolds would give a larger opening. although I'm happy to be corrected if there is a better solution out there. I looked in to large pocket doors and couldn't find any large ones. here's the thread as there were some other good suggestions in there for you.

following with interest and when you find a solution please can you let us know as we have a similar space between our entrance hall and kitchen/diner! ?

good luck to you @Eddy. I admire someone willing to make such a big change to their life in order to be happy. I wish you all the best. have you thought about approaching the Job Centre about re-training courses? I thought the government were doing a campaign recently to get people retrained in to new industries.

we're having 197mm top chords, I'm just going to fill with insulation (obviously leaving the 50mm gap) and then put PIR on the inside against the chords. I believe that's a pretty standard way of doing it? means don't need to pay for thicker trusses.

I have heard of them and they were on our shortlist of companies to use. I was impressed with them as well, the price was very reasonable and we weren't completely put off from them after going to see a property they were building although there were some things we weren't 100% sure on so in the end we chose to go with Flight Timber as we got a better feeling for the quality of the build for them that we went to see. if the quote is good then go see a house that they're building to see the quality of their work. or just do that anyway before they quote! then it'll save time for both sides if you're not interested from the off. ?

about 10 years for us and 2 previous attempts at purchasing something falling through but now we're about 2 or 3 months away from breaking ground! Welcome Heather!! stick with it and I'm sure something will come up eventually.

this! for me it will be hard to let go of that and trust a subbie. but I know I'm going to have to as I can't do it all myself and be finished within a family acceptable timeframe.

do you mind telling us how long it took you to do on your own and how much you did, i.e. m2? it's one of those things that I'm thinking about doing but it will all depend on the time it will take compared to the quotes I get in for it.

I had a timber frame company that refused to use posi-joists as they'd had a bad experience with deflection on them. it goes without saying that I didn't use them as I don't want to be drilling holes in I-beams to run cables, pipes and MVHR ducting! I'm sure that if that TF company had just designed for a less deflection on the posi-joists it would've been fine.

you're quite a way ahead of me! we probably won't break ground until Jan 2021 so I think I'll be following your install with great interest. ?

Yep. Plan is for a loxone system.

we are going for external blinds which we believe are a good solution. although not as cheap as building in an overhang they'll also reduce solar gain in the non-summer months when the sun is lower. plus, for us, it reduces the need to have internal curtains/blinds in those rooms!

yep. it was initially 12mm but after reading some threads on here I decided I didn't want to take the risk of a bouncy floor and asked them to reduce it to 8mm deflection. another win for this amazing forum!

I asked the TF company to design our first floor joists to an 8mm deflection which they did at no extra cost. our floors should be solid as a rock as the joists are 300mm centres.

just checked my 13th edition and he still has the model house for price references but the Case Study is his own self-build. I'd suggest the 13th edition (or latest) is always best to get for the few pounds saved by buying a second hand version

if you're going to go back to planning can you start just start over again with a house design and layout that you want from the off rather than trying to adapt someone else's plans? that's what we did. when we bought this place it had approved planning for a bungalow and outline planning for a 1 1/2 storey house. we didn't want either of those (although the bungalow would've been a fallback approval in case ours got rejected) and got an architect to design a 2 storey with basement and full pitched roof house which we, eventually, got through planning. now we get to build the house that we want. it's taken a lot longer than had we just put a minor amendment to the existing planning but it'll (hopefully) be worth it!