Annker

I actually have found a back to back frame and cistern here, didn't know they existed but looks like a good option where space is tight. Good luck with the planning.

@garrymartin I now am attempting to solve the back 2 back concealed frame challenge, and very appreciative to find your post, as even Geberit themselves seem to be hiding this fitting from the public Can I ask if where you found the Back to back frame diagram above as it doesn't appear on the product page on the Geberit website? Did you actually fit two frames back to back

It is work but, work with a return (although it may not be a necessary return) I'd add dealing with tyre kickers on market place is more work, certainly more painful!

Only difference I have with my cellar vs your garage is the cellar is damp, not very but not bone dry either. Although I guess the PIR wont be able to trap any dampness within the floor build up, that is the main concern I have.

Due to a IWI spec change I now have a lot of 40mm and 60mm PIR sheets that need either reselling or using elsewhere in my renovation. There are three potential situations I think they maybe be used as additional ceiling insulation fixed directly to the underside of GF joists (cellar ceiling), 1st floor joist (GF rooms ceilings) and 1st floor ceiling joists (1st floor rooms ceilings). The original plan in all these instances was to solely fit rockwool between the floor/ceiling joist, given its characteristics (easy of friction fit, acoustic and vapour open) and I still do that at the very least. Overboarding with PIR prior to plasterboarding will obviously increase thermal insulation performance but are there any drawbacks? Obviously ceiling height will be reduced but I have high ceilings and regardless lowering them in bedrooms and cellar is not a big loss. I have never seen PIR used in this situation so would appreciate others opinions. And just to add I don't plan/want to batten behind the PIR prior to plaster boarding unless necessary. Or go to the faff of taping the PIR joints to provide a VCL layer, which I don't think is required here.

If anyone can recommend a good heat & plumbing contractor with experience (and who regularly does such work) of full system installations a DM of their contact details would be great appreciated. Added to the usual pain of finding a competent contractor, I'm finding it particularly difficult as the usual channels for recommendations only return plumbers who seem to focus on boiler servicing and leaky tap repairs. In my experience those contractors who focus on that work dont have the interest in committing to a project that will last longer than a day; they prefer to get in, out and paid the same day and some don't have the knowledge of putting a full system together. Or if anyone knows a register/resource, or any pointers indeed, to find this type of contractor that to would be greatly appreciated also.

@mjc55 I'm just referring to a liquid applied roof covering. I used Restec Flexitec 2020, it is a flexible grp membrane @IcevergeJust came to mind that the breather membrane is probably there to catch any drips that pass the primary covering, its position directly over the PIR which serves as a VCL threw me.

@Iceverge interested to know what the purpose of the breather membrane is here? I've just completed a warm roof, I would describe it as the conventional build-up. Roof covering (liquid in my case) 18mm osb (Thermally broken fixed into joists) 150mm pir Alutrix vcl 18mm osb Roof Joist Plasterboard and skim (Yet to be completed) I did reasonable research before opting for this build-up but after going through the process of assembling it together a number of drawbacks/shortcomings became evident I will not use this particular design again. I'll post a full critique when I get a moment.

Typically you would pattress out areas of wall that are going to have fixtures prior to plaster boarding

Interesting take on IWI solutions from British Gypsum, (I've based the studwork from this spec). The most recent version of their GypLyner Independent System incorporates Isover Steel Frame Batts; however in a previous version from a couple of years ago they were pushing PIR as the insulation, interesting to wonder if this indicates a move towards a more vapour open solution? I imagine BG are specing Isover Glass fibre (and not mineral wool) is due to them both being owned by St Gobain. I wonder what are the vapour permeability performance of glass wool, Isover claim "Achieves Eurofins Gold certification, the highest accreditation for indoor air quality" whatever that means. May give them a call to hear how breathably they believe it to be.

I called Rockwool tech dept with some queries. Asking whether Rockwool can be bonded/adhered to brickwork, (specifically to ensure it stays against the wall as wood fibre can) the response was no it can't as it would delaminate. Furthermore the advice was not to use RW in this situation as there would be a condensation risk if the batts were not held tight against the wall, the person I spoke to went as far as to advise to use the "alternative insulation I mentioned" i.e wood fibre. They did however confirm that Rockwool is breathable and entirely suited to installation in older properties, so a mixed response, maybe even a confused response... Regardless I worked up the build up below using Rockwool: Gypframe 48mm "i" studs fixed floor to ceiling at 600mm c/c without intermediate support "i" studs stood off existing brick wall by ~20mm 75mm RW45 can only be obtained in 600mm wide batts, hence studs at 600mm c/c rather then the more robust 400mm c/c RW45 is fitted tight against the existing brick wall, ~20mm of insulation behind studs to eliminate cold bridging, Friction fit of insulation batt around the "i" profile of studs keeps the batts in position

Yes I had considered doing that, I have plenty soft sand on site so will mix up a 50/50 sharp/soft gauge tomorrow. I suppose given that the parge wont ever see weathering soft sand will be OK, it may even fill the finer gaps.

Thanks for all the input @Iceverge @Mike @Redbeardand all others, very appreciated. So WRT a smart VCL, the jist is that even small gap in the VCL will leak much more domestic bourne moisture into the wall buildup through air movement, than the VCL can return back into the room through vapour diffusion? Therefore an imperfectly installed VCL* (smart or standard) hinder the drying ability of a vapour open wall built up. *Agreed here the reasonable assumption that a perfectly retro-fitted VCL is a unicorn.

Re the parge coat I had in my mind that it would show up any gaps in the mortar joint we had missed with our initially pointing pass, and it has illustrated a few so perhaps we will give apply a second parge coat over what has been done and apply thicker going forward. Perhaps I should have specifically stated my plan was to use the Itello plus membrane rather than saying a vcl; is Intello Plus a vcl? Regardless I had in my head the inclusion of the Intello Plus as a supplementary layer, added in the understanding that it will not completely eliminate vapour diffusion into the buildup, it will leak but it will also allow drying to the inside.

I think this is a good build up. One potential issue I'm trying to get my head around is how/will the stud work keep and maintain to keep the insulation against and in full contact with the wall. The perimeter edge of the insulation boards wont always align with the stud centres and where they dont line up wont the whats keeps the insulation against the wall? Perhaps the second layer of insulation between the studs is necessary to ensure the first layer closest the wall stays against the wall. I've nothing against the cost of doing a WUFI analysis but I'm concerned it will be another case of "this or that" "may or may not" work. I'd rather just assume a vcl is needed and fit it. I imagine it could be double sided sticky taped to the metal studding and then plant on batten on the metals studs to create the service cavity?