Thorfun

oh, right. so water from the screed going through the insulation downwards which would hit the slab underneath? nothing to do with damp rising up from below? but would've thought the concrete slab would be pretty impervious to water penetration, no?

thanks. not planning up updating the drawings tbh (costs more money!) but if BCO insist then i will. our ground investigation also shows no radon requirement but good to know i can get a formal certificate if required.

no changes, it's just that the SE drawing didn't have the insulation under the screed and is missing the sole plate but the architect's BR drawings that went to BCO did and BCO didn't say anything.

no yellow where we are. 🙂

floor levels are correct from plans in this specific section. it was always the plan to have a layer of insulation under the screed and on top of the slab. not done any calcs on benefit for heat capacity but 50mm EPS is a lot cheaper than an extra 50mm of liquid screed. 😉 above the basement, though, we were originally going to have a hollowcore floor but at the last minute changed it to block and beam. this meant that the floor level was 50mm lower that originally planned so we have 150mm to fill to get to FFL and so i'm adding 100mm EPS above the B&B above the basement to get a 50mm liquid screed level. plus there are extra savings as i can use UFH pipe staples rather than click tracks fixed to the slab.

no. we didn't need Radon barrier. GI didn't show any so we just used basic DPM. np at all. 🙂

I think we're getting our wires crossed here @nod! our external walls have a strip of DPC under the sole plate. I apologise that the original image doesn't show that detail but here's one that does. so this is already built as is shown. we have a DPM under the insulation and structural slab with DPC strip below the sole plate and TF attached to sole plate. so all good so far. above the slab I am having a screed to cover the UFH pipes. below this liquid screed I am adding 50mm EPS100 to build up the depth (which reduces the thickness of the screed) and also to fix the UFH pipes to. do I still need a DPM under that insulation? it is internal and sitting on a structural slab that is wrapped in DPM externally. hope that makes sense!

well, it's all a bit moot now anyway as the superstructure is up and all the foundations were finished and paid for about 18 months ago! but we have clay here and are surrounded by woodland and we have a basement which these above ground 'arms' of our building are against. so it's quite complicated but i asked the SE for an insulated slab under the basement and 'arms' and that's what they gave me. if it's overly cautious then i'm ok with that. better safe than sorry.

but even if my structural reinforced insulated slab is already wrapped in DPM below ground? seems superfluous to then DPM on top of that already wrapped in DPM slab. 😕

coz the SE said so!? 😉

morning all. I'm pretty sure I know the answer to this one but I'm just after confirmation before I do something stupid. our ground floor rooms not above our basement have this makeup below ground. so the entire insulated slab is wrapped in a layer of DPM. Do I still need to put a DPM below the internal insulation that I'm putting down before the liquid screed. (obviously, I know about the layer of DPM above the insulation before the screed). from my search I've seen other posts where a layer of DPM is done under the insulation but that's because it's direct on the ground so not sure that is relevant in my situation.

thanks all. guess we'd better get shopping for basins first then! will ask more questions once we have those and 'temporary' fitted.

afternoon all. I'm resurrecting this thread as, sadly, I'm still not finished with my first fix plumbing. I still need to do the basin/sink/bath/shower waste. focusing first on basin and sink waste...... is there a standard height above FFL that I should run the waste pipes to? or does it completely depend on the basin? I would've thought there was a standard basin height and so that would lead to a standard waste level. Also, is there a strict requirement for maximum falls as there is with foul waste? if so, what is it? I presume I can do vertical drops and then the required fall into a boss on the 110mm waste pipes? I was going to just use 40mm solvent weld pipe for all basins and sinks. is that ok and the correct thing to do? I seem to recall @Nickfromwales saying something about 32mm pipes furring up over time.

got some and is certainly sticky! great colour as well.

the above 2 statements really, to me, defeat the main benefit of self-building and that is building something bespoke that you want and not just something that looks the same as someone else or something similar to 'improve pp chances'. you run the risk of building a house that someone else wants rather than what you want. seriously reconsider this. also sounds like the architects are being a bit lazy. could do with chatting some architects who are passionate about designing a house for you! just a word of warning here....we bought our plot because the previous owners bought it with a bridging loan and then couldn't sell their primary residence and it got to the point where they just had to sell one of them. put both their primary residence and this place up for sale and whichever sold first they'd keep the other and either stay where they were or build their dream home. they ended up losing loads of money because of the bridging loan and not being able to sell their primary residence. just beware, i'm sure we're all aware of how long selling a house can take and how fraught with danger and stress it is without having high interest bridging loan payments to pay or the risk of losing it all to a bridging loan company.

+1

yes (in my opinion)

Get a condensation analysis done by the manufacturer of the insulation. They can also advise on the location of the VCL.

it's a liquid screed. already done the prep work for one load. i promise you the chance of getting the liquid screed under the DPM will be minimal but i'll be foaming all gaps between EPS sheets (if there are any) and taping them for good measure. the benefit of self-building is you can belt and braces everything! takes ******* ages though. just ask @pocster.

i'm all for a sticky about due diligence but it still might not help some people. i did due diligence on our TF company (Flight Timber). i checked the accounts, filings at Companies House, spoke to previous customers, site visited a build in progress, did web searches. all looked good and they built me a good timber frame. a year later they were out of business and some on here got stung by that. so part of due diligence is looking for reviews and if some saw my reviews of how happy i was with the house then, it could be a major part of the decision to go with them only to lose money. so you could do all the due diligence in the world but still get stung. although i guess you reduce the risk of that happening.

unless he treats it as a loss leader to get the experience and references on his CV?

nope. afaik, ridge height is from ground level. so the height of the ridge above ground level.

Well will you look at that. It is a thing! https://www.sheetplastics.co.uk/jaffa-tape-50mm-x-25m

Would foaming any gaps be good enough? And do you mean gaffa tape? Or is Jaffa tape a thing? (Checking Google now!)

Surely the neighbours building in their garden has set a precedent? Should be a massive argument for approval right there.