Redbeard

Why not face-fix the frame to the wall inside the garage, so that the frame is wider than the opening? If we assume the stop-beads to be 0.75 inch each (a guess) then that gives you a door width of 34.5 inches.

Hi. Apols if you've said this before, but what is the existing eaves ventilation like? The staining on the membrane on the RHS looks like mould due to poor ventilation. Are you going to mess with the roof at all? For all I've said about not usually venting the ridge, if there's any Q over the 'quality' of the ventil'n at the eaves you might want the extra 'belt and braces' of the ridge vent. In terms of how much of a 'drop' to have at the apex, answer is enough to get a really good level of insulation at that point - say 300 mineral wool or other quilt - 'on the flat' . Make sure to get a really good 'hug' between the PIR and the quilt.

@ProDave, what I have in mind as a ridge-board in a typical Victorian terrace roof (approx 125 x 25) is (a) definitely not a beam, (b) meant to have collars below. However I have on a number of occasions seen 'rusticated' attics where the collars have been removed and the soffits plasterboarded right up to ridge-board. Droooop! If you are lucky there are 2 purlins each side lower down and the rafters were spiked in (or some of 'em). @Mr Punter I may be wrong but I have always been of the view that, unless the ridge is vented (which most old ones aren't) you *do* need ventilation from one side to the other. You need an 'in' and an 'out'. Air is drawn through, AIUI, by differential pressure at each 'end', and if there is an 'in' but no 'out' the potentially incoming air has no incentive to travel. I am not as convinced as some that ridge vents are essential, but if there is no ridge vent (in my view) there must be eaves-to-eaves through-flow. One of the ventilation acoutrement manuf'rs had some good info on this but b*****ed if I can find which one.

"Floor? Not sure but my googling says this may be up to 1.2. Does this sound right? - If so, I guess the windows don't make sense to go for the extra £4k." Search Floor Perimeter/Area ration for an expl of how floor U values are calculated. This site (https://warmafloor.co.uk/support-centre/u-values/) has a good explanation. Not sure that in actual 'comfort' performance it's going to seem the same for a solid floor as for a (ventilated) suspended timber floor.

@Mr Punter. You said "It is fine to insulate right up to the apex". True if there is no ridge-board but if it is like the roof in the OP's first link the between-rafter insulation will surely close off the cross-ventil'n. I always go for a small dropped ceiling. I am even doing so in my extension which does not have a ridge-board, 'just in case'!!

@Furnace, I am sure you have 'been here' already (https://www.gov.uk/government/organisations/natural-england/about/complaints-procedure) but there is at least an escalation path (however much one might feel that it might be made of fudge and long grass). How do you get on with your MP?!

Is this just for aesthetics? It may be too late but I'd have had the blocks flush-pointed and simply painted. It is, after all, a garage... Also not sure you'd want a gritty top-coat inside, unless you don't like skin on your knuckles! @ProDave: Snap!

"What im after is general building skills to take me through my projects" . Can you elaborate? What skills do/don't you have, and what do you need?

And if you are really good and thorough your clients will get used to the fact that they effectively get a project management service for free. One of my long-standing clients (ex-clients, I am not contracting anymore) said 'we love working with you, as we don't have to worry. You do all the worrying for us!'

As above, if it is on an external wall vent it to outside. That way it does not pick up warm moist air from the house and then condense it near the top of the flue. Win, win!

''Is there a certain way they should be replacing the door to maintain airtightness.'' As you imply - 'properly'!! Yes, no less tape than was there first off, and if the original taping was as cr*p as some I have seen then not so much more, as better applied. And if they go to use plastic 'plank' ask them to do a proper job. Good luck.

Thanks @Mr Punter. Bit scary on price, but then I guess Lindab (steel) would probably be no less. Anyone got experience of Lindab Ogee? Edit: Ah! Don't think Lindab do Ogee!

For cable and ducts you can buy grommets from, for example, Green Bldg Store, or make your own with EPDM and air-tightness tape.

Where is the ventilation going to be? If the PIR is very carefully and tightly installed you can run the ventilation up between the PIR and the membrane, having a dropped 'ceiling' at the ridge so that the ridge board (if any) does not block the cross-ventilation. But 2 comments: 1. BEIS Best Practice guidance now suggests 50, not 25mm gap (https://www.gov.uk/government/publications/room-in-roof-insulation-riri-best-practice). Yes, it's not really a room in the roof, but you are seeking to mimic the insulation strategy of one. And (2) You are going to all that faff of insulating the entire sloping roof simply to house the MVHR unit. Why not just stick-build an insulated 'MVHR shed', with no insulation on the 'floor' (the first floor ceiling within the footprint of the 'shed') and you can wrap it in cheap mineral wool at 300-400, rather than a relatively unexciting 75mm PIR? Note that what your roofer describes is not a Warm Roof at all, though it may give you a slightly warm(er) roof space than if you had not added the PIR. It won't be that warm, though, as you have added 400mm of mineral wool on the first floor ceilings to make it cold.

Do an 'invisible mend' on the soakaway position.

I ordered a whole load of C24, and when the delivery came some was C16. Took that part of the order back to the yard and out comes the bloke with an ink-pad and a stamp... Oh look! C24! The official explanation was that all their timber could be graded C24 but if they stamped it all thus some people would think they were paying over the odds, when all they wanted was C16. So they stamp some of it C16 and some C24. It must be true.

Can anyone recommend a supplier for 125(W) x 100 deep black alu ogee guttering, fittings and fall-pipe? Did a search and am now too overwhelmed to buy anything! Thanks

No, absolutely not fine! But depressingly common. I have had a contractor tell me the same thing, but being told it is fine does not make the insulation value any better. If the 2nd (under-side) layer is not completely tight to the first (between-rafter) layer, and the ventilation is working as it should, then you may even get thermal by-pass - cold ventilation air getting between the layers of the sandwich and effectively negating the effect of the between-rafter layer.

Yes, water-resistant plasterboard exists, as do cement fibre boards for shower panels etc, but loads of people have (maybe shouldn't have, but have) tiled onto bog-std plasterboard in the past with few or no issues. If the grout and all the perimeter joints are good then where does the water get in? I'd stop worrying for now, grout it well and re-do any mastic as required. Stick a note in your diary for an annual check and re-tweak as required.

What about costs of insulating the existing walls? Part L of the Building Regs will apply to all the elements of a conversion.

Looks a bit *too* black to me, but here in S Yorks (and I am sure other areas too) we have 'Black mortar'. The (lime) mortar was made using an aggregate of mixed sand and steelworks or colliery slag. It's awful stuff to hack out, as it was also used in basecoat lime plaster. I think as a theory that does not stand up, though, as if I understand you correctly the render was over the lot, and from what little I can see the render looks like sand/cement and thus probably much more modern than to date from the 1920s/30s heyday of 'black mortar'. Oh well, it was worth a thought!

@Chris HB, see www.heraklith.com , for example.

Wood-wool and lime? Using it on my extension as I want to avoid plasterboard and gypsum. Heavy, and not cheap.

Hello, You say 'Hampshire, Suffolk, Wiltshire'. You also say you need to be near specialists etc. Should 'Suffolk' read 'Surrey' or do you just have 2 disparate search areas?

Welcome! There's a wealth of experience on here so I am sure you'll find what you need. If it's general (eco) retrofit perhaps also have a look at https://sdfoundation.org.uk/wp-content/uploads/2018/01/2015_bristolsolidwallinsulationguidance.pdf and (Scottish) SEDA Sustainable Renovation guidance: Chris Morgan, John Gilbert Architects: https://static1.squarespace.com/static/5978a800bf629a80c569eef0/t/5beca5f021c67c2280e66de3/1542235691571/Guide+to+Domestic+Retrofit.pdf Also look up the Gov't's Best Practice guidance for under-floor insulation, internal insulation of solid walls, room-in-roof insulation and one other (I think) that escapes my fevered brain just now.