Off topic: Infill slab so moisture comes up between wall and slab. Hate infill slabs. There is a thermal bridge between the wall and slab below the insulation. The vapour barrier won’t do much to stop temperature transfer. It’s actually really difficult to stop thermal bridging with slabs. There is always somewhere that bridges. Door entry, patio entry etc etc.
I heard there are issues related to OSB glue in warm roofs stopping moisture from going through and reaching the breathing membrane, thereby creating damp, rot and decay to the boards. Have you built warm (non walkable) sloped roof without OSB? Rafter/vent - Insulation - Breather membrane - counter/batten and tiles?
Hi, I normally put a dpc membrane under the insulation boards, (belt and brace’s) and on top also when doing a warm roof you need a vapour membrane under the insulation.
Full cavity fill with wool is not the best. The outer wall might not be completely waterproof (hence the dampcource) and the rockwool will loose its structure and its insulation capacity rapidly when wet.
Good video very interesting to see the detail you are employing. I am about to dig out an old concrete slab that was laid down on an 1895 house, to get insulation down with a reinforced concrete slab on top with underfloor heating embedded in 6 inches of concrete with stone tiles on top. I intend putting the upright insulation up to the concrete level, idea is to use the concrete slab as a heat store so 2 weeks to heat up and cool down.
Not sure why you popped up on my feed, but I'm glad you did! Your accent clued me in that you might not be far away from me. I have an existing single storey extension on the back of my house which was added by the previous owner. It can get very cold, and acts like a heat sink for the whole ground floor. I suspect the insulation (particularly in the roof) is not adequate. Do you do remedial work for existing buildings at all, or could you recommend someone in the North East who does? Thanks!
Hi Chris, I’m based in Wallsend but we cover most of the North East and yes we do remedial work. If you visit www.lambertconstruction.co.uk and go to Get a quote. Just fill your details in and I’ll get in touch and see if you would like us to pop out and see you.
Hi Phil, thanks for your comment. 80mm PIR insulation beneath screed gives floor a U value of 0.22 w/M 2k. 👍 unless it’s now changed. This was nearly 2 years ago and yes BC signed it off. We are still working to building control drawings that state 80mm PIR insulation
Hi, I've got a small extension piched roof that I'm insulating with kingspan. The rafters are 6x2 and the kingspan is 75mm thick. Should I just double up on the kingspan? Would appreciate any advice from you
@@sten40too1 The internal wall is sat on the ground. The only other option as someone else has already commented on here would be to use something like foamglass at the bottom of the wall to isolate it from the ground but it's not a common practice in the UK yet as far as I know anyway.
That mineral wool becomes useless IF gets wet for any reason in the cavity. You should put in Rigid insulation or rockwool that wont absorb water. The best would have been full external insulation for a new build. Why not externally insulate?
@@ianlambert284 I know its more money but still.. I would not put that yellow wool in the cavity. That extratherm insulation would have been better choice as well in the cavity. Probably more money again, but.... What is the brand of this cavity insulation that the architect recommended?
Tbh Im only a first year carpentry apprentice and when I seen the yellow insulation in the video I raced to comments to have my suspicions confirmed. So im also very interested to know what brand of cavity insulation was used. Thanks. 👍
Unless I missed something in your description, surely you have a large and continuous cold bridge between your cold slab and the inner leaf which are touching each other? Also as someone else said in the comments about that 'cavity insulation', without knowing the actual product specification (what was it incidentally?) it doesn't look like it's suitable for a full fill cavity.
Hello Fraser, thank you for your comment. They’re only touching each other below the layer of 80mm PIR insulation and there’s an insulated up stand. It’s done exactly to specification by someone who actually knows what they’re talking about. The cavity insulation is Knauf dry therm cavity insulation if you must know. Suitable for insulating a cavity
@@ianlambert284 Hi Ian, thanks for taking the time to reply. First of all, I appreciate the time and effort you've taken to make and upload the video, so fair play to you for doing so. We all know as soon as you do that, you're exposing yourself to comments and criticism from armchair experts who often tell you "....you should have done this, you shouldn't have done that". You've just done what you were contracted to do which is build what's on the drawings. Thanks too for advising about the DriTherm spec, that makes as difference to knowing it is indeed suitable for full fill cavity insulation. It just looked in the video to be a more open type of mineral wool - just goes to show, you shouldn't go by appearances! I have to say though that my assertion there's a continuous cold bridge between the slab and inner leaf still stands. The slab is clearly 'cold' (the insulation is above it) and it's continuously touching the inner block leaf. The only thing the "insulated upstand" you refer to is doing is separating the warm screed from the inner leaf. I accept the cavity insulation is helping the inner leaf remain warm, but I'm really surprised the BCO signed off that base detail. I'm more surprised that the architect designed it with such a detail! I say that as a fully qualified architect with more than 35 years experience, so I do - hopefully - know a bit of what I'm talking about. I know this'll maybe sound really arrogant and elitist but is the person who prepared the design drawings definitely an 'architect' (legally you can only use that term if you've done all the years of training and sat the necessary exams to get ARB accreditation) or were you just using the term in a sort of generic way and meant 'the person who did the drawings'? Apologies if you were referring to a different insulated upstand that's not visible in the footage and that's somehow breaking the direct connection between cold slab and inner leaf but based on what I could see in the video, the slab and inner leaf would appear to be touching so there's definitely a cold bridge. Once again, cheers to you for doing the video and responding to the comments, it's appreciated.
@@giotto4321 correct,he did say he wanted to use a thermal block but was told not to.i would also put at least a 80 mil plasterboard on walls as well never enough installation.
As soon as the render starts to allow water to penetrate through the wall your gunna have loads of damp on inside wall, you basically have a wet wall ( outside) and a dry wall ( inside) your supposed to have a gap between insulation and outside wall to, a) allow air flow and b) not allow damp from the outside wall to cross the cavity to the inside wall, this is why the cavity wall insulation never worked and it cost millions of pounds across the UK to suck all the crap out
Still building as you did in the 1940s then… Jesus….. this is soon 2022 and we send ships into space. How Long did This extensions take? If you out undulation under the slab which technically you could avoid. And put insulation externally you could avoid all of these nonsensical expensive details!
@@ianlambert284 are you not going to put insulation between the rafters seen in the roof then? - vapour berrier should be on the warm side and not om the cold
sorry Chris, at dpc level the damp proof should go across the cavity and then up the internal skin, otherwise you will be bridging the cavity with the item that is meant to be protecting it.
I will mate .Full fill cavity insulation the cavity tray should go behind the insulation the damp can track across .with partial fill cavity the insulation goes up the the back of the insulation
