junglejim

Thanks Nick … the pictures didn’t load previously… looks good… really useful 👍

Thanks. Posi’s are 22cm from very top to bottom so hoping I might get more than 100mm insulation in there. Good suggestion on the strong backs. I do have some narrower channels with no strong backs so predominantly going to use those but there will be a few places I need to scallop out. 👍 Do you have photos of your ceiling build up? Would be interested to see and get a visual in my head. cheers

Thanks that’s useful. Still trying work out the best build up for my ceiling. The posi joists upper cord is about 45mm and there are regular noggins with the same gap above so thinking maybe 50mm Rockwool rwa45 then MVHR ducts then another layer of acoustic insulation. I feel like the ceiling should have as much insulation as I can get in but realise I also don’t want to be insulating the wiring . I’m probably way off here so really interested in what others do… another steep learning curve!

My MVHR parts have arrived 😀 I have plvcu ceiling/wall plenums and wondering the best way to mount within the ceiling. The mounting tabs are useful but not sure whether to go direct to the underside of the 22mm egger floor above or whether I need to fit a piece of timber for each one and screw into that. Any advice and photos would be really appreciated. Thanks

Thanks Nick that picture’s really useful too 👍

Thanks Nick. I assumed the 100mm would just compress slightly which i don’t think would affect acoustic performance too much?

Thanks John. That’s interesting. I was pushing the insulation right up to one face and running the electrics behind where electrics are only on one side. I’m wondering how easy the slab will stay in position if it’s in the Centre.

Possibly a can of worms question but my internal studs are 89mm deep and we’re looking to use Rockwool rwa45 slabs. First question is thickness: local merchant stocks 50 and 100mm so was going to go 100 but now wondering how best to manage wiring ie to sockets and light switches within that? Many thanks

I’m wondering what folks use for manifold water system. I like the way it’s done in Scandinavia and they seem to use pex-a. Local merchant has suggested easy lay but I’m not sure of the differences, advantages etc or best system to couple either with for connections etc. Any experience/advice/photos appreciated. Thank you

Thanks John sorry I wasn’t clear enough…internal face of external wall.

I’m wanting a couple of sockets on external walls they are battened at 600 centres with 38x50 and have super quilt then osb and timbers frame. I’m wondering if anything has any tips on getting back boxes into here. 38mm depth sounds ample. With a 25mm shallow back box I’d be looking to recess 13mm so not much but struggling to get any kind of noggin etc behind. I’ve tried the telescopic metal brackets but still struggling as the depth is much shallower than they are designed for. Any ideas? … I’d rather not bring the whole wall out for a couple of sockets. Ta

Thanks for the detail. I think now that one I counter batten the ceiling there may be enough room beneath the strongbacks to accommodate the ducts 🤞 really useful info though so much appreciated.

My posi joists are joined with cross members like the attached. I’m wondering if can drill through those or take out to run MVHR ducting along the length? The open web is great for running across the building but I also need to go parallel to joists. Any advice appreciated thank you

Hi, I’ve got my MVHR designs but wondering about coming up through the floors deck (above posi joists). I have one section where all of my upstairs ducts will come through as o 7 ducts each with 75mm diameter. I’m wondering whether I should cut a rectangular section and add noggins around the edges of deck or individual circular holes or something else? Thanks

I’m going to be adding battens to the underside of posi joists to ensure a flat surface and additional service cavity. I’m wondering the best size to use (was thinking 25x50) and also trying to work out hope to finish the edges where they overhang the joists to the wall. Any photos of similar appreciated. Thanks

Thanks @JohnMo any recommendations on where to source manifolds for this in uk? I can find lots of ufh manifolds but struggling with domestic water distribution. Thanks

I’m currently planning my hot and cold water layout. I like the idea of the ‘home run’ setup with pex runs from a central manifold. Its a lot of pipe though and I’m thinking a smart spring might be to zone the house and run zones from the manifold then tee off from the zone to the appliances. my logic for home run is that we’re doing timber frame build and I don’t want joints in inaccessible locations. The home run setup doesn’t seem so common in the uk as it does in Europe so wondering what folks think? thanks

Thanks that’s really interesting. I’ll take a look.

Thanks. Building is 15x10m with upstarts in roof space so total floor area approx 300m2 so not massive. That’s really interesting to know what you’re using in Scotland.

Thanks for all the help. Clearly have a lot of homework to do! I was hoping the plumbing company would help with this. Here’s the heat calcs they’ve run but I’m not sure they have factored in the efficiency of the build and other aspects such as MVHR. Im not sure where to start in terms of doing calcs myself so any help really appreciated. ps. Location is Guernsey so no extremes in temperature.

I’m trying to get my head around heating design. We are building close to passive house timber frame. I have ufh downstairs and want provision for radiators upstairs. I’d like the ashp to part heat dhw if possible so presumably unvented indirect cylinder. A plumbing company locally have shared suggested design but is generic and what I’ve read is that low loss headers are not best with passive house. Any advice welcome as Would like to meet with them to talk through. Thanks Proposed ASHP Layout - Charmaine.pdf

Thanks. Does it matter how much overlap there is. The battens are about 60mm off the floor so could tuck underneath and tape the overlap without lifting the battens.

On most walls there’s enough space to lap up underneath by about 7cm without removing battens. But presumably would still need taping regardless so not sure if there’s any advantage to that.

Yes prefabbed. Came like that with vertical battens

Just working out best way to tape this junction. The vcl is lapped around the cassette from bottom floor to top. Should I trim and lap under the ybs and then tape or just tape direct to the ybs as it is… seems like there’s no gain in folding and extra work. any thoughts? Thanks