Thorfun

Hi @ADLIan, in my situation we have the following buildup from inside to out: VCL Joists 70mm PIR between joists Firrings to 1:60 fall 18mm OSB 100mm PIR 11mm OSB fully adhesive single-ply membrane This has passed all of the condensation risk analysis and the VCL (will be an AVCL actually as it'll be the same membrane I choose as the airtight layer for the rest of the house) will stop moisture from the house get in to the joists. What happens to any moisture that does get in to the joists though? it can't go up as surely the single-ply waterproof membrane will stop it escaping above? I trust the condensation risk analysis but I'm just confused as to what will happen to any moisture that get's between the joists?

if I can add my limited experience to this subject... We have a balcony that is a 'link' between the main house and a flat roof room. like this: the intensive wile meadow green roof if a warm roof with 190mm of PIR above the joists. The balcony was designed as a warm roof with vacuum insulation panels (think Optim-R from Kingspan) but due to the exorbitant cost of those and also a mistake in the design we ended up with not having enough room for a warm roof. We are now having a hybrid roof for the balcony section with 70mm PIR between the joists and 100mm PIR above the joists. This has been through a condensation analysis by Xtratherm and it has passed. The important detail is, as has been said above, the VCL layer which is below the joists and any penetrations need to be sealed properly to reduce the risk of condensation. So, a hybrid roof is a faff but it's definitely possible if the relevant calculations have been done and you have a document to prove it. hope this different perspective helps.

I get the feeling you'll be disappointed when the timber cladding goes on. ?

good luck!!

Greetings! Apologies for the crass title but I am still a kid at heart. ? After a brief delay due to Covid-19 the carpenters were able to attend site and erect our timber frame. Thanks to the accuracy I insisted on and ensured for the coursing blocks the sole plates were a doddle and were done in no time at all although we did have a bit of rain and I had to get the puddle pump out! We used Flight Timber for our timber frame and they have their own lorries with cranes built in and so each stage of the build was delivered by the lorry and then craned in to place. Here’s the ground floor panels arriving. It took them just 2 days to finish all the ground floor external and internal wall panels. The speed of it all is very impressive. Then the posi-joists arrived These took a few days to do but thanks to the 8mm designed deflection and 300mm centres they are rock solid even across the 6.2m spans. It’ll be a bit of a nightmare trying to run MVHR, electrics and plumbing but we won’t have any bounce on the floors! Plus when the sun shines through it creates some lovely lighting effects Next we had a weeks delay as Flight didn’t have any chipboard flooring in stock as they were let down by their suppliers. This was a frustrating delay but with the current material shortages not one that I should really grumble about too much. It was eventually delivered and the chippies got on with laying it and the first floor panel starter plates. And then it was on to the first floor wall panels. These took 2 days to do as well and so within a couple of weeks of starting we had both floors done ready for the attic trusses They were also a couple of days delayed due to Covid-19 but arrive they did They didn’t take long at all to go up and I love the symmetry of them Then it was another week or so getting the roof finished and building the vaulted ceiling in our entrance hall etc and then they were done! It was 18 days on-site from start to finish. Amazing to see. I took some time-lapse footage and you can see the video below: And so we have a superstructure! The roofer is not far behind so my next blog will be about the roof slates and Solar PV array. Thanks for reading and until next time…

sorry @BotusBuild I missed this question. I'm not sure to be honest as they were applied by the basement contractors. I recall them mentioning having their training on the product and I can only presume that FIS were happy with that as I have a 25yr warranty for the waterproofing and my warranty company haven't requested any other information on the subject.

thanks Dave. our pipe will be behind a wall that runs through the larder and then goes in to the plant room in the basement and then out underground so I could actually do with that pipe cooling down those rooms! ? thanks for the study link and the summary. I'll be putting some Rockwool in between the studs of internal walls so I'm hoping that it won't make a difference for me, but if it does I will just accept the extra 20W of heating load. any particular reason for this? is it due to water ingress or some other factor?

How big of an impact in reality will it have? Is there any data or have there been studies done? It all sounds so very doom and gloom!! What if the pipe that’s vented is insulated or boxed in and the boxing in insulated? Will the cold from the pipe move through the connected pipes and affect all other soil pipes? I’m struggling to fathom how it’s possible that one vented pipe can cause such an issue! we did speak about venting sideways as well but that’s still a penetration and will surely have the same effect? one of our soil pipes is near the garage so maybe venting that one will have less of an overall impact?

nice one. I did speak to our BCO about it today and she said you can do it but it's 'best' to vent at the head. and she said that again to reiterate it when I made the point about venting at the STP again. so I have taken the hint and will just vent out of the roof but we've agreed that I can use one of these slate vents (https://www.slate.uk.com/product/nature-vent/) which is a lot less obvious on the roof than a pipe or mushroom. I'll just have to make sure the penetration is well taped and sealed.

he did mention something about writing a book and retiring. then he realised that he'd be bored sat at home all day so, thankfully for me, is carrying on doing my roof

my roofer has started today and we're having natural slates fitted so I thought I'd pop out and ask him for you. ? he said the same as @markc in that they shouldn't bend the slate but it should be snug. he also mentioned that the slates shouldn't butt up to each other and there should be a slight gap between them to allow for lateral movement of the roof. thought I'd pass on that little gem in case it's needed.

this is an interesting subject for me as I've started thinking about it. didn't I read somewhere on this forum that you can have the open vent on the sewage treatment plant and have all AAVs in the house? Our BCO is visiting site on Monday so I'll chat with her about it anyway but I'm sure I read someone on here had that.

I agree with the comments above and suggest speaking to a different SE. we had a 3.5m-ish dig for our basement and it's scary how deep that is! my mind couldn't comprehend it until I was actually there to witness it. I definitely wouldn't be wanting narrow 3m deep trenches if there was another solution. and there is always another solution!

so the BM will take the frame batts back but the Metac will cost me an extra £600 when compared to using the frame batts and is on a long lead time (probably not available this side of Christmas) so I think I know what my decision is going to be! it's just so hard to quiet the voice at the back of my head that tells me I'm doing it wrong. ?‍♂️

exactly what I said to them but they had slopey shoulders and carried on with the 'not recommended' line of answer. yep. again that's what I said! ahhh...someone who is just as cynical as me. ?

thanks Dave. I remember reading your blog and posts about it which is why I'm sure it won't be an issue but when the company says things like "As the Isover Timber Frame Batt 32 is designed for timber framed walls, we do not have any test data to support this within the pitched roof application. Thermally, it would be acceptable but you will need to ensure that there is no risk or slumping and it stays in position once installed." that makes me think that there's no BBA certification for between rafters and I will need to check with BCO if it's acceptable.

I was speaking to Isover technical department today to get a condensation analysis on my roof make up and when I said I was using 140mm and 50mm ISOVER Timber frame batt 32 to give me 190mm of insulation between the rafters they said that between the rafters they recommend Isover Metac (https://insulation-uk.com/products/isover-metac) as it was designed to go between the rafters and the frame batt may not be self-supporting. this surprised me and I've already bought the frame batt 32 so to change to Metac now would be a costly mistake. I believe that there are many on here that have used the timber frame batt 32 (and 35) between their rafters although it does seem like many use Knauff products. Anyone ever had issues with using timber frame batts between the rafters? I am putting 100mm PIR below the rafters so would think that would hold the glass mineral wool in place and would presume that the timber frame batts do not slump otherwise they'd not work in walls. do I just crack on or speak to the BM about returning the frame batts and going with the Metac?

or go to a different company where 3g will make a difference?

Can you get water cooling for your gaming rig? Might reduce the generated heat (and noise) and also allow you to overclock more ?

I've looked in to and thought about burning the battens but I think it'll take a lot longer than paint. our local BM has suggested this Superdec paint from Sadolin (https://www.sadolin.co.uk/products/sadolin-superdec-satin-opaque-wood-protection/). We've used it on a previous house for exposed timber but I wonder if it's overkill for battens (it is rather expensive!) or if there's a less expensive product that we could use

and if I did that I'd have no wife either. errr.....hang on a minute. ?

If only!

not something I've looked in to and just don't have the budget for it at the moment! I'm hoping that our 10kWp array will produce enough electricity on the good (and maybe some not so good) days that we can drastically reduce our reliance on the grid and simply pay the higher cost of buying from the grid if and when we require it.

not installed as the superstructure is still going up. but it's almost all paid for. we've decided to get a single phase inverter rather than 3-phase inverter even though we will have a 3-phase electricity supply. the house is only going to be run off a single phase and this way ALL of the generated electricity can be used to run the house and charge the battery and then excess can be exported. the research I did revealed that net metering and 3-phase smart meters are hard to come by at the moment and I just didn't fancy the extra complexity of exporting 2 phases and then importing on the single phase especially when our application to the DNO for a 10kW export was accepted. so, long story short, only 1 battery required on a single phase inverter for us. I think this is one competition you will win.

sounds like you're throwing down the gauntlet! must.......resist.......