Thorfun

So that would be one of the ‘smart’ membranes? Like the Intello Plus?

Don’t most manufacturers do their own version? e.g DuPont/Tyvek, Proctor, SIGA, ProClima, Protect, Gerband etc. with so many options it’s hard to know where to start but (as well as the recommendations above) you could check the Passiv House Institute? https://database.passivehouse.com/en/components/list/airtightness_system

https://www.ecowho.com/tools/r_value_to_u_value_calculator.php

does all your plant fit in to that? our plant room is 3.3m x 1.3m but we have a separate room for our comms and electrics (1.7m x 1.3m) and was a little worried about fitting everything in to the plant room.

our BC said that she would send off the SE calculations to the BC engineer to look over.

I have been quoted £50/m2 for labour and materials for internal block walls, in the SE. spoke to another bricklayer and he said that seemed reasonable. hope that gives an indication as to how expensive it is down here. feel sorry for my kids as they won't be able to afford to buy their own houses so luckily there'll be enough room for them to stay with us for as long as they need!

so you're suggesting that the MVHR is brining in hot air making the house hot? I would've thought sun streaming through a window would cause a greater increase in internal temperature?

I can only advise you to speak to a structural engineer. our building control needed to see structural engineer calculations for our build (a lot more complicated though) but I presume that'll be the case for even a simple build.

so that'll be about £36/m2 down here in the South East then, if we're lucky. ?

can you stop the heat getting in? i.e. reduce solar gain

interesting you say that as you're right that the cement bag says 4-1 with ballast mix but the ballast bag says 6-1. so I just made it up as I went along. like you say, it's just a light weight GRP box.

so I didn't learn this today but what I've learnt over the last few weeks that the basement contractors have been on-site is that there isn't a problem that can't be solved with a hammer. rebar in the way? smash it with a hammer formwork dirty? smash it with a hammer nut won't tighten/loosen enough? smash it with a hammer I'm surprised tool manufacturers make any money as it would seem that the hammer is the one stop tool that will fix anything and anything else is just superfluous to requirements.

nope. just thought I'd mention it as I was having a discussion with the guy between Anhydrite screed (which we've been specified) at 50mm and sand and cement at 70mm. thought it was interesting that it's normally stated that 70mm minimum for sand and cement but with the chicken wire (or possibly fibres added to the mix) you could go thinner.

this is what I thought as well but I was talking to an old plasterer/screeder and he said that sand and cement screed can be thinner if you put chicken wire in the screed!! not sure if he was winding me up or not though. I guess anything is possible. ? @nod you ever heard of this?

thank you! just the information I needed. appreciate it. :-)

cheers. sadly we didn't get PHPP calcs and our architects used a firm they use to do the thermal modelling before I found Enhabit otherwise I would've got them to do it. but it's done now. I'll drop Enhabit a quick mail to discuss the potential of putting the comfopost in now or leaving space for it later and will make a decision from what they come back with. Enhabit are doing our Solar PV and ASHP/DHW as well. been very happy with them so far.

hey @Bitpipe. sorry if you've answered this elsewhere but how did your EPS get attached to the basement walls? I know you didn't have an external membrane so didn't have to worry about penetrations in that Type A waterproofing but did you use fixings or some form of adhesive? if adhesive what did you use? I need to make sure the groundworkers use the correct adhesive to attach our EPS to the type A membrane without using mechanical fixings!

not got them yet as we're not out of the ground yet, but I will be getting Warema blinds from Corner Star (https://cornerstaraluminium.com). Depending on where you are there might be a Warema seller closer to you but I've been impressed with Jon @ Corner Star so far in my dealings with him. but the proof is in the pudding as they say and I won't have them installed for quite a few months so I can update on my dealings with them more after that.

the vast majority of our windows/sliders have external blinds and where they don't we will have a brise soleil so we should be able to control the heat getting in nicely when combined with the proposed Loxone HA system. we had a TM59 Thermal Analysis Report conducted and they concluded: "Most assessed areas would not overheat according to the TM59 methodology, some rooms may experience short periods of elevated temperatures, however, these have a low enough occurrence to be not considered as overheating." So I'm not sure that active cooling would be necessary. I presume we could 'bolt on' the comfopost post installation if required but that's a question I can pose to Enhabit who have designed our MVHR system. I was just thinking I could run a couple of extra pipes from the ASHP for possible fan coil units at a later date during the build. even if they're never used they're there just in case. hope you get in to enjoy your new house soon! ?

Hi @Dan F. are you finished and in yet? just wondering if you had any sort of update on the ComfoPost with the recent hot weather we're having? we're having a Zehnder MVHR unit and wondering if the ComfoPost does enough or if I need to think about fan coil or AC solution. Cheers.

Cheers. The reviews mention the blade is a bit thin and the bottom of the cut can be not square. Are you finding that?

Don’t suppose you could link to those blades could you please? I’ll have a lot of PIR to cut in the next 3 months and reducing dust would be great!

I think it was in reference to the timber frame moving/expanding/contracting etc but if people have first hand experience of flat green roofs being laid on top of GRP and they've not had any issues then that's a pretty good indication that it's ok to do! ?

we're having a couple of flat green roofs and the roofers I've spoken to have said that on timber frame GRP has been known to crack and would recommend single ply for a green roof. (random hit from Google for single ply solution https://www.bauder.co.uk/roof-systems/waterproofing-systems/single-ply) comments?

hi all. I've been doing a bit more reading on basement airtightness and vapour control (I know the thread subject heading is about airtightness but I think that airtightness and VCL seem to go hand-in-hand) and it looks like with insulation on the outside of the basement a VCL shouldn't be used in the basement. this article: https://www.buildingscience.com/documents/digests/bsd-103-understanding-basements says: "If basement wall systems are designed and constructed to dry to the interior – regardless of where insulation layers are located – interior vapor barriers must be avoided." so, can anyone who is much smarter than me confirm or deny this? it seems to me that I can wrap the ends of the block and beam flooring in airtight membrane/VCL and then stick that to the basement concrete walls and NOT take it any further down the wall. The external Type A waterproofing membrane won't let moisture in and so the basement is, afaik, designed to and constructed to dry to the interior and, therefore, no VCL should be used on the basement walls. comments on this please?!