Redbeard

Was there anything in your purchase 'stuff' which states an air-tightness test result. If not, ask the developer what is was. It may cost around £400 to get a basic A/T test which will give you a 'number' (in m3/m2/hr or air-changes per hour), or a fair bit more to get A/T and thermography at the same time. De-pressurise the house with the fan on a day when you can get a +10 degree C diff between inside and outside temp, and you get an IR 'pic' of the leaks. If the discrepancy between the developer's stated no. and yours is significant, ask awkward Qs.

BC and Planning are separate, so if the amendments you made via Planning are 'material' (my use of the word, not 'Material'), and have an effect on the B.Regs elements (The cladding changes from 12.5mm cement board and render to 100mm wood-fibre and render, say) then that would have an effect on the B. Regs side of things (Part L in this case, but feasibly another Part if the cement board acted as an anti-racking board and the WF didn't) then maybe you need a discussion with your BC body, but as you say, that's a private firm, not the council. So, as far as I am aware, No, your chosen BC body will do that. Note my background is all in refurb, not new-build in terms of direct dealings with BC, but I cannot see LA BC being interested in specifics of a build being 'policed' by A.N.Other BC.

@sgt_woulds I appreciate the 'pulling up', and I usually recommend WUFI to my clients anyway, as each case is different, but my suggestion not to have a membrane was not without (WUFI'd) precedent, from a refurb we did on a cement-based pebble-dashed 19th C house 8 or 9 years ago in Yorkshire (micro-climates vary!!). Nevertheless you are right that WUFI is advisable in the vast majority of IWI cases (in my vie whatever material you are using), especially if you use a merchant who offers it free anyway. My own preference, when I was contracting, was to aim for 100mm WF (c0.35W/m2K on a 225 solid brick wall - no so far from the Part L 0.3 target) and then use WUFI to tell me it's safe or not. A general note - If you don't find merchant offering WUFI then independent 'WUFI-wranglers' are a bit few and far-between. I have been told of one, though I am not sure on Buildhub's advertising rules. *Mods,( @Nickfromwales, are you a mod - I think so. Sorry if I am wrong) can you confirm it's OK to give the name*? I can't see why not. Edit: I see I did give the advice to use WUFI in my post on Monday at 20.35. I read @sgt_woulds's post as if I hadn't, and was surprised at myself! If framing I agree with your use of Intello and have used a great deal of it, not least in my own house.

Well, it involves bits of bent metal, so it's 'after my own heart'. I'll have a closer look later.

Many would say so. I say not, as the VCL is there on each sheet, but not at the joint. You go on to say 'Traditionally', nothing, which is why I prefer working with insulation only (say foil-faced PIR), taping the foil face , then battening and hten boarding. However a few people have started to use 'fluff tapes' like Contega or Pavafix Win, over which you can plaster, so that would work, although strictly that 'bit' of the VCL is not in quite the 'right' place. I think you can get a 'tighter' VCL if you use bare boards and separate plasterbds. I rarely use foil tape - it's too variable. I prefer to use Pro Clima or similar air-tightness tapes.

What renderboard had you planned previously? Does it have to change? Do you want to get more insulation? You could use wood-fibre board (lambda somewhere 0.039-0.044W/mK). I used Baumit Silikon Top. It comes in varying grit-sizes, from really gritty to almost smooth.

OK, try again! I cannot see how wide your butt joints are, but could you have it galvanised with one end flat and the other rising and curling over the curved section of the next tile. But how does one stop water running down the strap? And again...! Brackets shaped to sit over the ridge with 'wings' rising up the triangular edges of the ridge tile to 'hug' them - maybe 2 per tile, and somehow with some 'spring' to the 'wings'.

Oh bu--er! I have just looked at your pic again. I was thinking of bog-standard Victorian terrace ones like mine, where each one has a 'hood' which overlaps the next. That won't work with your plain-ended tiles. Will see what else I can think of.

I think in a straight fight between your mortared wall and a combine I know which I'd bet on 😉but it may help against the sheep. Sad, though., It looks the business.

Hmmm... a) I share your pain! b) Maybe there is (though I am not certain for refurb) due to the feeling that mortar and gravity are not going to hold your ridges forever. I wonder if you could satisfy them if you did some clever metal strap-wrangling so that you could trap down each 'plain' end below the 'oversail' of the next. If you used, say 3mm steel and worked it hot (or got a fabricator to do so - all they need is your sketch and dimensions) this could work. But it would have to 'work' for roofer and BCO. If I had such lovely ridges I would be happy to finish that myself if BCO would accept it.

The lack of a completion cert suggests it has not been signed off! (Surely). I always received completion certs for my jobs. The heading says 'Date of Completion Cert (If issued)' and the comment is N/A. I would read that as 'It is not applicable because there is no date, because there is no completion cert', but I see that in this case they use it as 'not available'. Either way I don't think that helps you, as it could be 'not available' 'cause they lost it, or because there never was one. Of course I could be wrong....

If you go with Wood-fibre you could go to a merchant which offers (dynamic, more accurate, condensation risk assessment) WUFI for free. Building Control depts are very variable. Mine used to be quite hard to get a conversation with, so if you were doing anything with any element of doubt you just had to go with your gut and hope the BCO agreed. Since they may only do 2 (or even one) visit(s) you don't, ideally, want to wait till you have done something (based on your best researches) to get a BCO opinion on whether you've done right. They should have no problem with an area-weighted calc, and should also be OK with you not quite achieving 0.3W/m2K (0.3 with WF may be an IC risk). I used to use the WUFI calc to back me up on that. On the other hand some merchants do a cost/benefit trade-off and suggest even less than I'd use. Not sure always how you get that past BCO. My feeling re WF is that if it functions without a VCL then you don't have a VCL to get wrong. Just go tight as a tight thing and stuff any gaps with 'fluff' (cutting 'swarf' mixed with water). Always use a (lime, in my view) parge coat. Views about gypsum as an under-layer vary. As I say, I have used PIR when the client cannot pay for WF, but I'd much rather use WF.

But surely the hole will be in the right place

I am sorry you have had a rough time. I picked up on the words 'acting as my electrician'. Are they one? If it were me I guess I'd be looking at the terms of the original agreement (which might be the 'feel' of it if it was verbal). Did any particular thing precipitate the decline of the relationship? Have they done of not done anything which might be of interest to Trading Standards? Oww! 'Multiple more thousands' sounds painful. I don't know much about the Small Claims Court but is there a clear breach of what you thought they intended to provide?

If I were doing something like that I would use Pro Clima's Intello (which is vapour-closed in low temperatures but becomes slightly vapour-open as te weather warms up, allowing 'dumping' of any accumulated moisture) as VCL, not the foil on PIR, so just make the wall as thick as you need to get the U value you want without the PIR, then it could 'breathe' (a bit) both ways instead of being 'blocked off' on the inside.