Redbeard

I realise this post is in the context of EPS-clad blocks, but a reminder that XPS also leaches the plasticisers out of cable sheathing. I was once puzzled as to why I could not move a 2400 x 600 sheet of XPS I found in a loft void. It came up a little but would not 'let go of' something. Found it had 'glued' itself to a series of lighting cables!

Can you? You'd probably need to ask your sol'r since, by doing so, you would be fettering their 'funding stream'. What about water disposal? What are the drainage arrangements? Are they seeking to get you to pay +30% on top of disposal as well as supply? (Or is drainage private?). Arguably it's a sound decision *not* to, for them, insofar as they can charge you if you don't do them. Or have I understood this wrong?

I am not yet engaged with AI except as a method of speeding up meat production, but here's what it says: "Generally, upgrading room-in-roof insulation does require Building Control approval if more than 25% of the roof area is being replaced or re-covered, as this triggers the need to meet current thermal insulation standards. If the work involves replacing or significantly upgrading a thermal element (like a roof), building regulations apply, and you'll need to ensure the insulation meets the required standards. " ..and that's the line I have followed. Bldg Regs defines 'renovation of a thermal element' as 'adding or replacing a layer' (of an 'insulation sandwich')

You have already answered your own question. XPS (I assume) was spec'd so that it would not become a wet sponge if flooding happened again. It has not been used. A dry sponge has, and a dry sponge will get wet in a flood. Obviously tricky as you say most of it is completed, but you did not fail to follow the spec.

If the specification of closed-cell material (XPS, I kind of hope, but OTOH it floats well) was specifically related to knowledge of the flood incident(s?) then it arguably matters a lot. If the builder had the specification it is also arguably their problem. If you expect (at least the possibility of) flooding again then yes, the use of a material which sucks is an issue.

Re my post: should read 'ask for *their* comments'

Have you notified the owners (presumably the local authority, with no budget for such works) that the lack of adequate drainage on their property is causing a periodic nuisance and asked for this comments?

Ow! So sorry to hear that. Hopefully someone on here can suggest a suitable person. Perhaps a minor issue, and perhaps most people will be VAT registered (I never was, and equally never was a 'window person'), but Deceuninck could have ruled out an excellent non-VAT-reg'd specialist there.

I guessed 'Micro-dumper' - and at least one variant is referred to as that. (https://www.cjhire.co.uk/product/industrial/hi-tip-narrow-dumpers/micro-dumper-2/) (No connection with that firm; just my first search result).

That's RD SAP for you! Vague data in; vague data out, plus the way in which EPC assessment was marketed as a money-making opportunity - 'Full-time wages for part-time work' was one of the mantras at the time. I did not believe it because I had seen a similar set of circumstances with (inland waterways) Boat Safety Examiners. A race to the bottom in terms of price and quality. There are still many EPC assessors who want to do a thorough job, but the early (and probably continuing - I don't know) over-supply of assessors meant that prices were forced down to a ridiculously low level. You are right about not liking (and I would add 'not being able to recognise') real construction. I wrote to the certification body of one assessor who did not recognise EWI in spite of all the 'clues'. I told them I was baffled. 'So are we'! They explained that they give all the necessary info in the training, and offer a help-line in case of doubt. To be fair you probably don't have to be a building professional to be a good EPC assessor, but you do have to have, or develop during your training, a proper *understanding* of buildings and of what may have been done to them during their lives, so that you can make an intelligent 'stab' at what is 'beneath the skin'

Are we at cross-purposes? I am talking about insulation in roof voids, on the flat, not walls.

@Pocster, could you post a cross-section of the attic room and the voids surrounding it? If there is, for example, an apex void and reasonably-sized eaves voids it might just be possible to stuff but not too (tight!) them ridiculously full of mineral wool (500-600mm?!) so as to get a weighted average of 0.16W/m2K.

Hang on, it's a long time since I dealt with rentals but does renewal of an HMO licence *really* allow them to move the goalposts every term (how long is the term)? And a Q - Is the '100mm assumed in the roof' PIR or mineral wool? And are there both sloping and flat ceilings? I assume so. No sweat (or not much) to upgrade 'fluff' in a void. More so to insulate sloping soffits, but it can be done. 150 PIR will give you 0.16 or slightly better. BUT I cannot, in a quick search, find anything on the web saying that they can require an upgrade to current standards. Of course I may be missing something. If we ignore the 'base case' R value of a roof (SAP assumption for uninsulated is U value 2.0W/m2K, therefore R uninsulated is 0.5M2K/W), taking the view that thermal bridging of rafters etc may more- or-less cancel that out, then 100mm of mineral wool (with lambda value 0.044W/mK would give a U value of 0.44W/m2K, a long way from 0.16. However if it is PIR it's 0.22W/mK, not so far from 0.16. And yes, they do mean minimum!

What U value have you been quoted for the floor? Is the Perimeter/Area ratio fairly low?

I should have said 'welcome' before I went ahead and answered your other Q. So belatedly, 'Welcome!'. All the answers are here. You just have to know the questions. How old is the house?