Redbeard

Cut the hole - seriously. (I suppose it does to some extent depend what the construction is but I am guessing that making a hole and subsequently making good will be easier than explaining to a twitchy would-be buyer why you've only got 90% of a warranty).

Who is providing the guarantee? Internorm (the 'kit' supplier) or the fitters? If, as I hope, the former, then they should inspect and sort.

I don't know EPS200, so I don't know for certain whether it wouldn't 'suck' at all in adverse conditions. XPS definitely doesn't, though, AFAIK.

Ah! That's different to mine. We trowelled on and textured (plastic trowel, flat, 'rolling on the aggregate beads') almost immediately, so the 'visual test for 'patchiness' ' was done as we went along. Edit: So as not to mislead, ours was not K Rend, but another, not dissimilar, product.

Ah, there's the rub. If I am seeing pic. 2 correctly then at least 1 joist (and how many more?) does not extend across the cavity. (a 'missed trick', perhaps, as the OP says (I think) that it is a newly-laid floor). Looks as if some brickwork and floor will maybe have to be removed in order to be able to 'sister' a new oversailing piece of joist alongside. Not knowing the nature of the sub-floor (is it moist, for example?) I would not risk suggesting some sort of load-bearing/insulating fill to that cavity.

Did they not sheet it up? When we did ours in an October, much later (as ever) than originally planned, we were watching the weather like hawks, and sheeting up with hessian after every pass.

Agree wholeheartedly. Always a very huge way outside my price range. Ultimately had my V twin the across the frame, and no chain! Please forgive the M/C-related hijack!

In my limited experience It was b----y hard to do an 'invisible mend' on patches like that. I hope your patches don't 'show'. My experience was doing it myself. If someone else is doing it for you then they have to try to get the 'invisible mend', and arguably re-do it if they cannot. Again, hopefully the pictures are not 'telling the story', and it's not what I think. EDIT: @Conor must have posted his while I was 'composing'. He got an 'invisible mend' - things can obviously be more positive than I suggested. Good! And good luck.

Hard to tell from a photo, but based on what I seem to see yes, I think I'd be a bit concerned. The 'bald patches' look like... well, bald patches, where the grit has not spread evenly. But maybe I am seeing what's not actually there... Are the 'bald' patches smooth?

Silly me! Posted asking where the Duke was, without looking at the 'thumbnail' pic! Too little of it to guess which model, for me.

Rather than metal straps we use to use (for a range of timber buildings) 50 x 50 sticks fixed to the face of the bottom beam and purlins and then screwed sideways into the rafters. Don't have a pic to hand.

No, but have you tried Allan Brothers? Never used their alu clad (which are imported) but a client has used several 'batches' of their UK-made timber windows and was v satisfied.

Good call, but the use of squirty foam at all will be governed by the answer(s) to the ventilation question posed previously. Squirty foam should only be used in well-ventilated conditions which, in my experience, often do not exist in sub-floor voids. Also having to use the gun at an angle increases the risk of sputtering and 'bounce-back'. ('Sputtering' when gun delivers liquid propellant instead of foam because the canister is not vertical, and 'bounce-back' when that liquid his a joist and splashed back, under your safety glasses (which you wear because goggles steam up) and you go to the local eye casualty. Don't ask me how I know...

... or is it just the bottom flange of a 'box and tray'-type lintel?

@Iceverge, I definitely agree with you in principle, but the part of the world you are in (and the size of the job) can have a big bearing on whether you'll get a cellulose blower out of bed... I've known colleagues struggle for large extensions, let alone one floor. I don't know if it still is, but Wales used to be a good place to be for cellulose. Is Ireland similar? I don't know where @Rocket Ronlives, but it could be pivotal w.r.t cellulose. I've talked about blocking 'unintentional ventilation', and you @Iceverge, have suggested cellulose and membranes, but I don't think any of us yet has (in this thread) explicitly stated the need for excellent cross-ventilation below the insulated 'sandwich'. Yes, getting rid of warm moist air from the house entering the void is good, but if *any* vapour-laden air gets into the void, which is now colder because of the insulation, there's a potential chance of condensation occurring on the bottom of the membrane. Good, unimpeded cross-ventilation (straight lines and diagonals) is a life-saver for suspended floors. Vents in one elevation only mean you have 'ins', but no 'outs', and the air 'short-circuits'. Edit: Come to think about it @Iceverge's idea of adding to the bottom of the joists could be done in home-made OSB/plastic insulation/OSB 'fillets' to cloak the thermal bridges of the joists. For example, perhaps instead of 50 x 50 PSE, 2 x lengths of 12mm x 50mm wide separated by 25mm PIR or EPS/XPS and glued up with waterproof glue. (I used EVA nearly 40 years ago and the 2 elements are still stuck together!)