Annker

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?

Studwork as required as the current preference irrespective of insulation choice is to plasterboard and gypsum skim finish the walls. Reason being I can do the boarding myself and then it should be easy to find a decent plasterer to do the relatively straight forward job of skimming (verses finding a lime plasterer) Ahhh, you think the parge coat may crack, is that because you think its too thick or too thin?

Update on applying the parge coat. We were applying using a sweeping brush to apply direct from a tub but finding that each dip pulls a greater amount of water and lime out of the tub which results in the mix remaining in the tub becoming progressively sandier. Initially mix was a full belle mixer gauge worth at 3:1, however we are having better results with a sightlier more lime rich mix and mixing smaller batches with a paddle mixer in the tub. Now the sand stays in suspension in the tub almost long enough to get it all used. Still undecided about which insulation to use. I'm actually now reconsidering using wood fibre boards now, for a specific reason I want the insulation layer positioned behind the studwork so the insulation is a continuous layer, however the difficulty is then how to keep the installation tight against the wall, as the studs only will only hold what is directly behind them. As wood fibre boards are typically bonded to the wall with adhesive they will stay in place against the wall regarding of studwork. Does anyone know is rockwool batts can similarly be bonded to the wall and if so with what type of adhesive?

As I said there is seemingly no consensus on the correct mix, but the majority suggest NHL 3.5 so that's what I went with. Open to correction but with the parge coat thickness on the wall ranges from 1mm to 3mm I imagine at that thickness using NHL 2 or 3.5 is a moot point.

Finally IWI has commenced onsite. The good advice given here has me sold on the benefit of a parge coat. I think no matter which IWI system you select a parge coat will sit very comfortably in the mix, its effectively the same material as a victorian brick wall (sand and lime) so little concern about introducing non-compatible materials that the building may reject. We have spent a few day pointing up the bigger gaps in the jointing, will parge now and expect much like a mist coat it will show up which areas need further attention. I'm mixing 3:1 Sharp sand to NHL 3.5. This mix seems broadly accepted to be OK, however I've seen @Iceverge add a shovel of cement and elsewhere others say NHL 3.5 is too strong, so again noo hard and fast rule it seems. I will say that its not as easy to put on as I thought, not in terms of hard physical effort but getting it from the bucket to the wall. I'm applying with a soft sweeping brush, the mix in the bucket need to be constantly agitated to keep the sand in suspension, or else you end up just whitewashing the walls. A lot of material goes on the floor, which when gathered and put back in the bucket dries the mix and so more water is required to bring the mix back to a brushable consistency. @Redbeardsuggested a pre-bagged mix which certainly would be an easier material to work with, but I figured I'd need 50+ bags so it works out to be a much more expensive option for my project. Here's how the first gauge is looking.

Below is a photo of it finished. I have a dig later to see if I have a photo of the EDPM detail, Illbruck have a good range of tapes.

I did a recent project with horizontally fixed sweet chestnut. For memory I used EDPM around the window reveals and head, tucked up underneath the membrane, then installed head and reveal boards (machined from the chestnut) which projected past the cladding. If I was doing it again I'd use pressed metal trims as the head & reveal boards.

I haven't checked the exposure resistance. The facade to be cladded is north facing (I'm yet to see rain drive against it), the house itself is in a town and well sheltered, we're ~30miles from the coast. Given that situates us in a relative non exposed site, I've assumed, perhaps wrongly, that even the least performing offering on the market should be adequate. I'm hoping the clipped together/non rolled joint versions will be satisfactory. I imagine they require less tools & skill making them easier to install but still should perform ok for a cladding install; for a flat roof I'd certainly veer towards the rolled joint.

Its a well appointed site, fully scaffolded and substrate will be fully finished ready for covering. I estimated the time taken similarly, I was thinking 2 installers x3 days would be a generous allowance. Ah the need for snipping makes sense now.

Thanks both @Russell griffiths and @saveasteading for the response. I got of ~£6k+vat quote for supply and install vm zinc to include; 8m of parapet capping 6m RWP & hopper 8m2 of cladding with 1no window penetration. To me it seems like a very expensive quote, making reasonable cost assumptions for the coping and RWP suggests a rate of ~£500 /m2 for the cladding element. I've called Catnic and Cladco, I will call Lindab also. (Metal solutions were also recommended here) Ideally I'd find a supplier that would take a look at my drawings/sketch and then spec the required trims (Cladco said they don't stock trims but can manufacture whatever profile I ask for) Certainly don't mind hiring or even buying a few hand tools for the job. Have you any suggestions for specific tools?

Can I ask if any the above poster have install the metal roofing themselves and if so was it technically difficult? I've some cladding to do, small area but a window penetration and the usual abutments. I'm a carpenter by trade and have done some lead work so resonable confident those skill will transfer across to metal work. Also Lindab appears to be some manner of partner (not manufacturer) of Greencoat, so when people refer to Lindab standing seem is that actually Greencoat?

I should have added that quote is the only quote I have received, I was expecting/hoping it would have been a more reasonable price and I could have just gone ahead with the order as I believe the installer would do a good job but I'm finding it hard to justify not shopping around now. I'd love to know what the materials cost is, as it hard to see there being more than 3 days labour (if that) for x2 installers. This part of the facade is a bit of a architectural feature and I think hard metal is the correct choice. I think alu coping and downpipe are a good choice. I priced some up online, material wise will cost ~(£1000 incl VAT) max.

On my ongoing extension there will be a vertical metal cladded area, approximately a 1.2m wide x 6.4m height, there will be a single window penetration within this cladding facade (.5m wide x 2m high) I have received a quotation for supply and fit of VM zinc standing seam to this area for £7k (incl VAT) the quote also includes ~8 linear metres of zinc parapet capping and a 6m zinc downpipe and hopper. The price is more than I had expected given there is only about 8m2 of cladding, granted there will be some detail around the window and where the cladding meets the brick splash course but nothing too involved. The parapet capping is a 4m run 90 degree turn and another 4m. Anyway this price has me know considering what self install options are out there. Has anyone any experience or options on them, I have seen Comex roofing as an option for one.

@MikeSharp01 A couple of years ago I was struggling to find a supplier for beads and then found these guys 30 mins from me, located in Kent and have a good range. https://www.ghsupplies.co.uk/plastering-and-drylining/metal-beads/qic-reveal-beads/

Fair play to you for taking the time to make this, much appreciated @Iceverge, I haven't watch it yet but will do this evening.

Yes its pricey but anything done at this stage will certainly be cheaper than rectifying works after decoration is done, its along that line of thinking that I'm happy to sell on my already purchased PIR at a loss. WRT to using RK38. Do you use it neat by its self or with sand as a replacement for the lime in the parge coat.

I've seen that system/video. I think the princple is broadly OK but I hope to be able to produce a more robust install myself and at a lower price.

I'm unsure if an Open Vapour buildup should be modelled in Ubakus, but when it is it shows a condensation risk. Is that what we should expect and accept on the proviso that been vapour open the condensation can dry to the inside? Same buildup but with the inclusion of Intello Plus VCL. @Redbeard I believe you were suggesting the inclusion of a VCL?

I'm coming around to mineral wool option, it would mean selling the PIR but that can be done at a minimal loss. The brickwork doesn't take fixings too well, so the studwork will be fixed at floor and ceiling level, no intermediate fixings to the brickwork, also the floor to ceiling height is ~3m, so that all points me towards using metal studding. With that in mind I'm unsure how mineral wool batts could be kept in place, tight against the face of the brickwork. Fitted in between studs will mean an absence of insulation behind the studs; hence a gap for condensation to occur (this will be the case with either timber or metal studs). I suppose mineral wool could be simply packed behind the studs or perhaps first install a full layer in landscape format, fix studwork and then infill studwork.