Iceverge

It's easy to do something like draw a layer of PIR taped correctly but another thing altogether to try to do it in reality. I built a passive house, really understood my junctions and airtighness layer, and did the necessary work to get it airtight. Having seen the level of detailing and labour required I think that attempting to do so in an old house with internal boards is absolutely futile. You will have leaks, you will have gaps behind the boards and you will get interstitial condensation. The impermeable nature of the PIR will prevent the wall from drying apart from the miniscule cracks where the vapour got in in the first place. My main preference for a parge coat and mineral wool is that good real world performance is actually achievable. Parge and airtighess paint is very forgiving on wonky surfaces and corners around timber etc. The parge is vapour permeable so all the wall can dry. The mineral wool can flex to old wonky walls so there's no gaps for condensation to occur.

TF as per the above description.

My proposal is to ditch the concrete blocks actually in this scenario. 20mm vertical cladding. 38*50mm battens across the wall 38*50mm battens up the wall at 600cc. Breather membrane 220*42mm studs at 600cc infilled with blown in cellulose. Airtight membrane. 45*50mm studs for insulated service cavity at 400cc. Plasterboard and skim. U value 0.16.

Ok, whats the plan something like this? 20mm vertical cladding boards. 35*50mm battens across the wall 38*50mm battens up the wall @ 400cc You'd need at least 8 fixings per m2 at a guess. 30p per fixing. 95mm wafer head screw and rawlplug. 215mm cavity block wall. 120mm PIR foamed to the internal walls. Internal face of boards taped. 20*70mm vertical battening for service cavity @ 400cc fixed at 400mm vertical spacing or 6 per m2. 60p per fixing 200mm wafer headed screw and rawlplug. Plasterboard ands skim. U value 0.18 You have 8 fixings externally so £2.40/m2. 6 internally but longer screws so £3.60/m2. Total £6/m2 and 14 holes. Add some extra for openings and waste £7/m2 and 16 holes. Assume your house is a quite small external wall of 200m2 thats £1400 on fixings, not too bad sounding actually. However you would have to drill 3200 holes into cavity blocks! At least 10% of them would pull out and fail because they're awful to fix into I think 3500 is still conservative. 20 fixings per hr say. 175hrs at a cheap labour rate of £25/hr. £4375 for labour of drilling and 5 weeks of absolute torture.

The parge is a mix of sand lime cement in the ratio 3:2:1. It is applied to make the interior face of your external walls as your airtight layer. You should return it on any internal walls by say 3-600mm to avoid any leaks at this junction. I choose 63 mm CLS timber because it is the thinnest studwork lightly to be any way straight. You could screw it to the wall but it'd need a lot of shims and drilling to get it straight and fixed. If you feel it us still wobbly you could fix it through with a hammer in fixing here and there to the wall. You'll need to shim it to avoid it being pulled out of line though Fix a top and bottom plate using a vertical laser level, mark your centres and cut your studs to fit and you'll be through it in no time by comparison. I would probably use 400mm centres but for the most efficient use of labour I would make sure its a snug fit for whatever your preferred batt insulation is. Normally 12.5mm plasterboard is best kept to 400cc.

Forks are not mega difficult to keep level, just take your time. If you get it wrong you can really make a mess of course! You can sling pallets with two straps and a hook too. Beware though the pallets have no SWL in this config and it can be hard on the straps. If you're careful it'll be a cheap way to move stuff though. These are what you should really use in that situation.

Sorry I should have said to put a layer of 20 x 70 strapping under the PIR on slope to create a service cavity too.

Sheeps wool is ace for clothing. I love my 100% wool jumpers. I wear them every day until they are full of holes. However I'm not a big fan of it for insulation. It's very dear and can attract wee beasties more than some other alternatives. I would not use it if you are budget constrained. Cellulose is a great option, as in mineral wool. I'm usually not mega keen on PIR boards but I think @nod is spot on here. My suggestion for the roof is this. On the slant, Slates Bituminous Felt 75mm ventilated gap 2x50mm layers of PIR with joints staggered and foamed. Inner face of PIR taped and returned to adjacent surfaces. Plasterboard Skim. Horizontal section. Ventilated attic 400mm of Mineral wool or celluloseabive and between joists. (better!)Membrane returned to all adjacent surfaces. 20mm battened service cavity. Plasterboard and skim.

Let me modify the above sentence for use in a super insulated modern house. "But first, writh uncomfortably by the fire, sweat dripping off the hairs on your toes, stareing into the lava hot, death furnace, as the steaming cocoa liquidifies your skin and the neighbours are asphyxiated by the emerging smell of melting human flesh".

I looked at the first picture you posted and held my head in my hands. In a different world you might be able to just lock the site gate and come back in 6 months,or a year, or two years when conditions were favourable. Alas impractical with all the paperwork following building . Another option would be to park the shovels and design some easier to build foundations like piles with a ringbeam or such. However we are where we are etc..... Before trying to pin your builder to the wall with emails maybe try to climb into his boots for a second. Take him to a nice cafe somewhere, on the clock, buy some buns, and have a grown up discussion. Importantly, listen to him. I know it's frustrating to see the budget and schedule slipping but I think it's the ground eating it. Not your builder. Resist for now the temptation to bolster the moral of men, up to their knees in sh*t, with dictatorial emails.

A Cavity wall is far less risky as the cavity will be either ventilated or insulated. A ventilated cavity will be excellent for allowing drying towards the outside of the inner brick. The insulated cavity will keep the inner leaf far warmer dissuading condensation.

But................... If someone was say, building a timber carport.......... With some glue you could bang one together in 5 mins. No routing or anything fancy. No ripping of ply. Is it an issue of making sure the horizontal "flanges" stay horizontal? I might make one if I have a few "two bys" hanging about

That roof looks fine and straight. As a side note though, it's probably only in such good condition because of the lack of insulation which kept the timbers warmer and less lightly to suffer from condensation. If you do insulate, you will elevate the risk of condensation significantly. To counteract that you'll need to install an appropriate vapour control membrane. What's your aim for the house? Do you want to flip it or live in it?

I'm stealing this. It makes a way more sense than "battens/ counterbattens"

What's you alternative, moistureboard? It's nothing special. I wouldn't build a boat out of either. PVA ain't gonna do much. Tank the hell out of the normal stuff and it'll be fine.