Iceverge

Did a back of the fag packet calc a few years ago and reckoned biofuel for planes would use about 25% of the worlds useable agricultural land.

Firstly I'm not seeing any ventilation in the bathroom? I would make sure this is completed as part of the remodel. Get a Greenwood CV2GIP ( keep an eye on eBay for a cheap one). Get an appropriate hole in the wall/ceiling venting to the outside. In any case I would maybe remove one bay of insulation to inspect the plywood sheathing behind it. If it's in good condition I would replace the glasswool. I would buy another pack of it and fill any voids in the current insulation. Don't use PIR or something impermeable. You'll only make trouble. Then buy a variable SD airtightness membrane. Something like Gerband Vario, intello pro clima or Siga Marjrex. Diligently cover the walls with it, taping all joints and penetrations. Do the same on the ceiling and tape it to the floor also. The aim is to 100% ensure that any drafts cannot blow through the wall Via gaps and cracks in the structure. Tape the membrane to the doors and windows with airtighess tape. Next run 50x50mm battens horizontally over the studs at 400mm centres to create an insulated service cavity. Add extra blocking for any heavy fixings needed in the bathroom. Insulate with 50mm mineral wool. Add some marmox board of jackoboard to the window reveals and head. Plasterboard and tile/skim as needed. Wall u value will be about 0.25 but it's the Airtightness and lack of drafts will make it quite comfortable. ( Ensure the floor+ceiling is well airtight sealed and insulated underneath too).

Good to know about the 50mm. I'm toying in my mind with methods to avoid the human suffering if concrete pours.

An option you could explore to save a few £ is to pour every floor to say 25mm short of final level with concrete and tamp it to get it fairly flat. Then get a pumped screed to make the final bit perfect.

When it comes to concrete work and newbies they will be of limited use, (myself included when I first did it). I've seen the pattern too many times. They'll appear full of enthusiasm, gloved and booted up. The first 5 minutes will be all action but they'll quickly tire, start leaning on rakes and wondering "is there a better way to do this" because they can't fathom how much suffering it is. They'll start job switching and going off on side projects "I'll just start over here in this room" forgetting they're making a mess for later. They won't have the "touch" required with concrete. When raking in front of a screed they'll be constantly banging it, or taking huge lumps and making holes or dragging the surface so it's like a rice Krispy cake. They won't be used to the time pressure and heavy work and will respond to the robust direction of the gaffer by sulking. When given a lighter support task like washing up (very important) they'll see it as punishment for being sent away from the main action. What you require is someone who has spent some time in the military, is a strength endurance athlete and is also a plasterer.

I would recommend you get some experience help with this as it'll be a mess if it goes wrong. What kind of team have you currently lined up? You could build an expansion joint into the doors to allow it to crack there. I wouldn't fret too much about DPC's in the walls but would ensure that the localises water table is well below it. You might need to add a french drain to the house if it isn't. The rest of the plan sounds fine.

The real question is how much Mrs Nod is worth. I seem to remember a pic of her slating the roof on Christmas morning.

I did every penetration of the envelope myself for this reason and designed out all but 5 wires through the roof membrane. I had an absolutely no blame policy if anyone accidentally made a hole. "Just tell me and I'll patch it up" It worked well.

Yeah it's pretty normal. You could apply to do something else but I'd say it's unlikely to be approved.

Google satellite pic of the roof please.

I installed a non borehole non anode stainless steel one and am taking the savings as my own guarantee. 4.5 years so far so good. Copper Industries do some nice guaranteed products. Maybe worth a call if you haven't purchased yet .

This will work perfectly. Controlling vapour is largely nonsense. The aim is to control the flow of air and in doing so not create any vapour traps.

Woah woah woah........ This sounds like the wall has an impermeable layer outboard of the timer frame. Any sketches or pictures of the build up please to help us understand? I very much doubt your membrane is a fancy low permeability one. In any case I very much suspect that the wall was drying to the inside rather than the outside. Putting PIR between the studs would trap the sheathing between two layer of low permeability which really is a no no. Pics please...

Airtight layer placement isn't as important as making sure it's continuous. It's drafts that carry vapor laden air, not diffusion etc. I would just do what's easier to install at this stage. Probably something like FM330 foam to fill any big gaps in every "box" at the end of the joists and then some airtight paint over the top. Airtight tape is also an option. The important thing is that is joins the layer above and below the ceiling. I'm slow to rely on the foam long term for airtightnss as it shrinks.

Stick build on site and fill the frame with blown cellulose.

In other news a tilt and turn will be easy to get. Is it idiot proof enough though. They're more ingeniously destructive than you could possibly imagine.

A door. You want a glazed door.

Also why WBP and not OSB?

What's the proposed wall cladding going to be? I would encourage ensuring the steels are completely insulated. If they are outside the insulation and get they will be a magnet for condensation and the timber will rot where it was attached.

DIY for sure. Draw a line with pencil on the frame to mark the edge and it'll be 100%. It's much easier to do pre install if you have the time alone with the windows. You don't need to go to germany for tape, it's the install that matters. https://airtightnesstapes.co.uk/products/3100-black-airtight-tape?variant=48903193100567 This looks similar to the stuff i used.

Wise. No amount of shading or decrements delay will counteract 30+ prolonged external temps.

Why not just tape the OSB?

Yes that would be fine. The internal layout matters somewhat on the location of your airtight layer however If you have a lot of funky junctions or timbers or internal walls that can't be erected post roof build I'd be in favour of moving the Airtightness layer to above the rafters. It should just friction fit I think. It's nice stuff but much dearer than the equivalent mineral wool. I'm a big fan of including insulation above the rafters. Keeps the timber thermally stable and you'll have less chance of rot etc. Ok cool. Is the design of the cut roof set in stone? Can I get a cross section of the proposed structure? Works both ways actually, structures can dry in as well as out. It's bad airtightness that is the culprit for interstitial condensation. A single hole the size of a 50p will let more moisture into a roof than the entirety of diffusion over a 100m².

Not me. Maybe @IanR

What units are your using for this new parameter?