Redbeard

Limiting U values are not targets, though, so as others have said the values achieved look pretty disappointing. The way of calculating compliance with B Regs for new-build is based on a sort of 'pick and mix' insofar as you could get away with higher-than-ideal air leakage if you had better fabric U values and vice versa. The limiting u values are simply 'it cannot be higher (worse) than this'. Is there a membrane behind the plasterboard? What's the insulation? If foil-faced is it taped?

I don't quite get the maths here. If we assume the very beginning of Oct I think that's 16 weeks to date, with a 2-wk extension taking it to 18. Have I misunderstood?

I don't know, but if your username is indicative of your build-style maybe you have individual founds for each post (a la Segal Method) and therefore minimal threat to trees and roots and the LA recognised this. Or maybe not!

Soffited. Was that the sort of (very short!) answer you wanted? Please give more detail if you want more.

I have, in the past, done a 'downstand' of PIR/plasterboard internally to cloak the thermal bridge caused by lack of CWI behind the fascias. Oversail on the inside by about 300mm compared with the est'd position of the top of the insulation outside.

On the upper left you can see 25mm of PIR between the (75mm) rafters, leaving a 50mm ventilation path behind. Below the purlin a further 100mm has been added to the initial 25mm, and all the joints and perimeters of the boards are about to be taped as the vapour control layer. On the right-hand side is the final stage before fitting the plasterboard. After taping of the joints in the 100mm board 50 x 25mm timber battens are fitted horizontally, screwed through the ‘insulation sandwich’ to the rafters, and a final sheet of 25mm PIR is fitted between the battens, giving a U value of around 0.16W/m2K.

If you want smooth (-ISH!) use a bagged product with mesh and do the first coat with a toothed trowel. The 'tramlines' of the toothed coat act as a depth gauge. Do a small (1m2?) test 'panel' first and you can mess with it and refine it till you feel confident.

OK. Will get to that later.

Ventilation is a potential issue. You need a 'dropped section' (small area of flat ceiling) at the top to form a 'plenum chamber' otherwise the only things getting ventilated would be the spaces between 2 rafter pairs. Look at manufacturer's bumf and see whether 2 vents is enough. And is there 'supply ventilation' at the bottom of the roof structure? (You need 'ins' and 'outs'). Apologies if I'm teaching egg-sucking! Common practice since 2010 (when insulation became a requirement of re-roofing) has been to leave a 25mm gap between insulation and the top of the rafters, and this (https://assets.publishing.service.gov.uk/media/61d727d18fa8f50594b59305/retrofit-room-in-roof-insulation-best-practice.pdf) - gov't Best Practice guidance which seems to have sneaked in without many people knowing - says 50mm. Having 'trouble-shot' a number of moisture-ridden room-in-roof retrofits I favour 50mm, but no void of any size is much good if it does not have the 'feed' and 'exhaust' - the 'ins and the outs'. I prefer 'raw' PIR, finished with battens and pl'bd, to insulated plasterboard, as it allows you to tape the life out of the VCL. Plenty of example in BH pic history, I think, but pics from me if anyone needs them.

To me thermal wallpapers are an illustration of the fact that a thin thing has all the insulation value of a thin thing. They have their place where other measures are not going to be done (perhaps in some rented properties) insofar as the slight increase in surface temp may hinder mould growth. Don't expect huge comfort increases or fuel cost reductions, though.

Is this it? https://www.ukseptictanks.co.uk/ecoflo-nonelectric-sewage-treatment-6

Golden opportunity to sort out the basics - insulation, air-tightness and heating - while you are going to endure inconvenience anyway. Welcome and all the best with it.

Hello. It all depends (perhaps among other things) on the foundations. If the foundation was calculated quite tightly for a single storey then no, you probably cannot add a 2nd storey without underpinning (reinforcing the foundation). Underpinning is generally (arguably should be) done by specialists, so in some circumstances taking down and rebuilding (and maybe taking the chance to get Planning for a bigger extension) might be not much more expensive. Oh, and hold on, it's at the front. I am not particularly well-versed in Planning, but there may be more limitations on the front elevation than others. Hopefully someone else will chip in on this one.

Kitchen floor tiles got me thinking generally. Have you had an asbestos survey/are you used to looking for it? No wish to teach anyone to suck eggs. If you haven't come across it much before can I suggest HSE, and particularly their 'Asbestos Essentials' as bedtime reading? Looks like fun generally, though!

This:(https://warmafloor.co.uk/support-centre/u-values/#:~:text=U-Values of uninsulated ground floor&text=In order to meet the,by the addition of insulation.) has a useful 'ready reckoner' based on the IP3/90 Information Paper. This (https://www.gov.scot/binaries/content/documents/govscot/publications/advice-and-guidance/2020/02/tables-of-u-values-and-thermal-conductivity/documents/6-c---u-values-of-ground-floors-and-basements/6-c---u-values-of-ground-floors-and-basements/govscot%3Adocument/6.C%2B-%2BU-values%2Bof%2Bground%2Bfloors%2Band%2Bbasements%2B%2B.pdf) from Scottish Gov't, usefully separates out solid and suspended floors which the other one does not.

It couldn't be a second pump, a 'secondary return' for the domestic HW cylinder, could it? Is there only one pump, or is it a combi boiler? If so, ignore my suggestion.

I think if it were me I might be getting ball-park prices from local GRP/EPDM flat roofing contractors with a view to offering the neighbour a 'sweetener' which could lie somewhere between a percentage of the estimated cost of re-roofing their exg extension on the exg deck and the full cost of re-building their roof to become a Warm Roof (like yours might become, clearances permitting - I'm thinking windows, flues, whatever).

Welcome! I assume those are not in priority order, but if they were intended to be I would switch 1 and 2 and fit in the current 3 and 4 around 1 and 2 (or 2 and 1!). Sounds like a good blank canvas. Will you be able to do all works while it is empty, or do you need to live there during works? Are you planning EWI? Edit: Just seen your thread re EWI. Cancel above Q!

But as @saveasteading says, get the test done! If it comes back negative you will know you were worrying about nothing, but you have climbed a steep knowledge ramp in terms of future works. Make HSE's Asbestos Essentials a 'must read' item.

+1 for the test.

For the future what about a 'slinky' cable and a chain so that you can hook the fitting off and get it far enough for you to do the bulb change on the landing - then hook it back on? Sky-hooks are a good, but somewhat less serious, possibility.

How old is the house? Victorian houses often had wooden dowels instead of angle beads. If you chop a little bit out of the corner and insert a dowel you can then re-skim the reveal up to the dowel. If you want 'chunky', broom-sticks are cheap!

Make sure you use *Airtight* foam. Illbruck FM330 is what I use, but Soudal (and probably others) do one too. Not all foam is air-tight.

You've probably looked all this up, but the Green Building Co (Greenbuildingstore.co.uk) has used Diathonite a bit, but internally if memory serves me correctly. Apparently v good for air-tightness. Can also be used for EWI, as you say. https://luneretrofit.com/ had it spray-applied externally a few years back.

Yes, but you mitigate that by returning onto the relevant wall (internal or party). Typical return is min 400mm-ish