junglejim

Thanks… that was my gut feeling. Do you think good above both?

Thanks for the reply. This is an internal stud wall on timber frame build. Raft slab. No dpm under the slab. Will lap up external walls but no bed on internal stud as within the envelope but had wondered about taping to the dpm strip under the stud. Have read that overlap alone is sufficient though hence confusion. ta

Argh I’m overthinking this so could do with some advice. Here’s a photo of my internal stud wall with dpm strips underneath. I was going to lift up the thicker black dpm and lay my floor dpm with double sided tape between the 2 but thinking now that it’s probably better to lay the floor dpm over both? I’m also unsure whether taping is needed or the overlap is sufficient? Paused mid job to think over a brew so any advice greatly appreciated. 👍☕️ @nod@Nickfromwales @saveasteading

Thanks for all the advice so far. One more detail I’m wondering is how high to bring the floor rpm up the stud work? It would seem to make sense on the external walls to lap up the concrete upstand (overlapping soleplate dpm) and then tape to the soleplate or sills or be left open at the edges and come up higher? or… extend the dpm higher to underlap ybs foil and then tape the joint between ybs and dpm

Currently building a new house and looking at my electrical planning. I’ve read somewhere that DC is worth considering as an alternative to traditional ac lighting circuits. Wondering if anyone has any advice or opinions one way or the other. Ideally looking to future proof and also with sustainability in mind.

happy Christmas. thanks for all the advice. There’s none underneath. It’s a raft slab.

Difficult to explain but here’s what I’m thinking. The difference from what seems to be the norm is not taking the perimeter strip all the way to the concrete slab. It feels better to make sure the insulation is tight/snug to the edges of the room. Unless the perimeter strip (green) is supposed to also provide some compression/expansion around the pir.

Thank you Nick for such a thorough response. That’s as I imagined. I’ll definitely be using the foam strip as advised by the screed company but think it’ll be better above the insulation rather than all the way to slab. These also suggested osb strips at the bottom of the studs to give the strip a solid backing to adhere to… makes sense although possibly belt and braces. Any further advice welcome 👍

Thanks… that’s an interesting point… was planning on taping it to the insulation and also to the stud

Thanks. The polythene is a skirt on the expansion strip to be taped to visqueen layer laid ontop of insulation. I’m really questioning the logic of running the expansion strip full depth rather than above the insulation… seems like standard practice to go full depth so I’m wondering if there’s something that I’m not understanding.

Thanks for the advice. The image I first posted was from Google and not exactly illustrative of my case (timber frame). I realise the external wall will need additional insulation such as 25mm perimeter pir up to ffl I think. My main question is around the use of the expansion strip. I’ve attached an image that our screed company has provided as an example of what to do. However my instinct is to run the pir right to the stud then install the expansion strip above. Unless it’s serving another purpose?

I’m a bit confused by what seems to be standard practice so must be missing something…. The advice is to fix the expansion strip to the perimeter prior to floor insulation. (See attached) Surely as this is much less insulating than pir it provides a potential cold route to the slab around the edge of every room? Would it not be better to fit the insulation tight to the edges and then add the expansion strip above this. Taping the ‘skirt’ to the top of the insulation / visqueen layer will ensure a good seal for the screed without the need to compromise on floor insulation? i also thought it was good practice to install a vertical strip of pir around the edges but does the expansion strip negate the need for this? I’m likely missing something so any advice greatly appreciated. Thank you

I’m just trying to work out the detail for pir insulation with ufh and screed at external door junctions. Along the exterior walls I think I need a vertical strip (25mm wide) of pir that will finish flush to the finished screed level and be hidden by the flooring and skirting. However where there are door junctions this will be against the bottom of the frame and the engineered floor will go over the top. In wondering if as it’s a high traffic area I should really use something like brigi foam at these junctions or am I over thinking it? Thanks for any help

Thank you for the thorough reply. The black dpm where your arrow is folds down and underlaps the dpm beneath stud partition by about 150mm. There isn’t any tape though but not sure if that’s essential? You’re correct to notice that the black dpm underneath the studs doesn’t extend 100mm … more like 50mm but the clear strip which also goes under the partition extends about 200mm. I’m hoping that’s ok and I can then tape the membrane that I’m laying over the concrete floor onto this. Thank you again, really appreciate any further advice you have here.

Top of screed will be just above no.2