Redbeard

May we ask how the archo suggests you achieve 0.18 on retrofitted walls? If it's via EWI that is probably OK. If it is via 'hard-to-the-wall IWI that sounds like interstitial condensation waiting to happen. What is the plan so far? Note however that if you can get to 0.18 rather than 0.3 (in actuality rather than on paper) it will/should be better for the occupants in the long term.

Post and beam. Search Segal Method. I have built from small sheds to a garage/workshop with the floor plan of a fair-sized bungalow. Some just sit on pads (conc slabs on a concrete-filled pit for each post for heavier buildings; slab only if the building is light and you are sure of the density of your soil. But if the building is too light do you need to hold down? Could be as simple as some threaded rod or perforated strap embedded in the 'pit' footing and fixed up to the post. May not be as quick as stud-frame but it's such fun!

Glue and dowels?

And if they do, you can calmly explain that the house as proposed is within the footprint (I think) and the height (I think you said) of the previously-approved application, but adding the 2nd storey made it work better as your lifetime home (without any detriment to the visual aspect), as you expect to be living in and contributing to the community for many years to come...

Do you mean there is some of the original garage remaining, with its original floor in?

You mention a try-out with PIR, but then actually 'doing it' with XPS. Can I ask why? And can you, as @Nickfromwales asks, confirm whether the floors are currently level from the 'main house' to the garage conversion?

Ahh! Thankyou!

...However it's cold whatever, so I would suggest you excavate the entire floor and do a good (250-300 EPS or 150 PIR) job of it. Have an upstand of insulation all round the perimeter too. Edit: @Nickfromwales post had not popped up till after I had pressed 'go'

Extremely likely, but... It is/was common to have a step down into the garage so that heavier-than-air fumes wouldn't automatically creep through to the house. If that were originally the case, and the floor levels are now equal, there's either (say) 150mm of concrete/fill there or perhaps a little insulation too (@JohnMo has just posted as I type so sorry if there's any repetition).

A very small truck for difficult (tight') roads. I am in my 2nd day of waiting for delivery of a bulk ('tonne') bag and due to dodgy parking the truck cannot get up. I would willingly pay a premium just to get the ****** stuff here!

Sorry, what is a 'paint point'? I thought at first it was a typo inadvertently left in, but I see it appears twice so presumably it means something. A web-search does not elucidate much.

Take careful measurements, take them outside and cut to size. Clamp together, with a straight-edge to supplement the evidence of your eyes. Mark sections, drill, bolt up. Check again. Unbolt, take up to the roof, lay sections out and bolt up in situ. At this stage I'd use spiked washers.

I think that door is one if the internal walls dividing the previous garage, so those will come down to make it back to one open space again Hi @ProDave. Yes, you are right. Unobservant of me!

Unless that door with the neckerchief on is a fire door it will need to be when you 'disconvert'. Also the original garage floor level will have been lower and un-insulated. Let's say that for the conversion they put in an insulated / floating floor. You'd have to take that out. Otherwise exactly as per @nod. Easy! While you are doing it, though, just check whether there ever was adequate insulation in the garage ceiling/ bedr floor. If not, you have the opportunity to remedy that while you are making other mess. I don't know the age of the house but potential risk that 'asbestolux'-type fire protection board was used. Take care when investigating. Also/or if the conversion involved taking down the ceiling, habitable rooms below/habitable rooms above does not require x-hour fire rating. Garage does. Check it has what you need. (** x-hour' because I cannot remember whether it's half-hr or one hour. One, I think.

Are you on site? Thoughts run to a big thermos flask which you fill up when you prepare you 'snap' every day, which is there when HSE come... They don't say *how much* HW.

I misunderstood initially (I think). I thought you were going to retire to the bungalow and rent out your house. I now read it and think it's the other way round. I realise bungalows are a bit like hens' teeth, but do you think there is a good market for a tiny bungalow?

37m2? Back in my housing management days 35m2 was a '1B 1P' - one (single) bedroom, 1 person and really tight. Do you have drawings?

It depends to a degree on how well-ventilated the disused flue is. It should be really well ventilated ideally, but in some circumstances the 'in' (at the bottom) will be from the inside of the house (an air-brick in the ch brst in a room), not from outside. Which is the case here? If the air feed is from outside and the discharge is via the top of the stack then I am not sure you have much to worry about re condensation. If the air feed is from inside a room then you may have something to worry about, as the 'feed' is of warm moist air, not cold drier air. The warm moist air can reasonably be expected to condense out in the upper reaches of the flue. Other protection I would argue is less necessary since you will have a padstone below, and arguably a small lintel above. You could put in physical protection at the sides, but I would prefer, say, slate rather than (potentially sweaty) plastic. (OTOH it probably won't be sweaty if the cross-ventilating air is dry enough, as above).

I usually seal the wall with a lime parge coat. Although it is often not done this is quite important if using PIR (I wouldn't, usually), as the condensation risk assessments you get from the PIR manuf'rs will usually assume very good breathability *outwards* through the wall, on account of having closed the breathability path off completely with 2 sheets of foil. If the existing plaster is lime-based you may get away with leaving it, and augmenting where it never was (often behind skirtings, for example, and between Ground and 1st floors). Just make sure to strip off any non-breathable coatings. I tended to use wood-fibre a lot more than PIR. Yes, it is expensive, but much better at 'managing' moisture from the room. Even if you decide to use PIR I would strongly recommend using PIR *and plasterboard*, but not bonded. Yes, each sheet of insulated plasterboard has a VCL, and when you join them together, they don't! If you use separate PIR (or other insulation) and VCL you can tape the life out of the PIR before adding the plasterboard. Yes, wood fibre is only about half the insulation value of PIR but is so much better in many ways. And it does not give off cyanide when it burns.

Flashband or similar are good 'quick fixes'. They degrade fairly quickly, though TBF the last bit I used is still surviving in a 'second-hand' sort of way. The lead or alu could be 'permanent' (theft excluded!)

I am definitely not an expert, but HSE is/are, and IIRC some of the bitumen-based adhesives had asbestos fibres in 😞 I assume you have already read HSE's Asbestos Essentials guidance. This is the one you want: https://www.hse.gov.uk/pubns/guidance/a23.pdf

As possible alternative to lead you could possibly get a good alu fabricator to fold you a cover in self-coloured anodised alu. Lead needs a good lead-worker; Folded alu needs a good folder *and* good measurements to start.

Lead, but do you think it's porous? If that were a cill I would not be expecting to have to clad it. What is the specific issue? (Sorry, perhaps have not read the 'that leak' thread closely enough).

Yes: https://assets.publishing.service.gov.uk/media/61d727d18fa8f50594b59305/retrofit-room-in-roof-insulation-best-practice.pdf Proctors used to do (may still do?) a membrane which claimed to function with no air gap. I have sadly seen numerous examples where serious condensation and mould have occurred with a nominal 25mm air gap (OK, so poor installation and possible insufficient size of eaves vents may also have been contributing factors. For 25mm extra loss of headroom I honestly no longer think it is worth the risk. If headroom is a particular issue on stairs (re BR req'ts) consider sacrificing 25mm of insulation in that area only.

Sounds like foil-backed plasterboard, the foil being a Vapour Control layer/barrier). On the other hand I have never liked it since, at every joint, there isn't a VCL. Is that picky? Especially nowadays when many use the VCL as the air-tight layer, I don't think so. and So if you can afford to lose internal space how about remove the plasterboard, 75 x 50 timbers horizontally at 400-ish ctrs (to suit insulation size), Yes, you still have a full-depth thermal bridge at the cross-overs, but life is not perfect. Either that or go over with some rigid board, such as PIR (I dislike it as much as many), taping all joints and perimeters as you go, and then 25 or 38mm deep battens screwed thro' to the frame and there's your VCL and service void. (and if you take the view that a hole in the VCL for the screw is a hole in the VCL, pre-drill, squirt in silicone and wind the screw through its own 'silicone grommet'. Or can you do EWI? For Best practice you'd still have to address the incomplete VCL but if it is done well it can be a very good thermal overcoat. Out of interest has your frame survived with little rot?