Redbeard

But that's their (or the sales person's) problem. They have delivered what you didn't order, and you want what you did order. You have every right to ask them to take these away and let you know when the correct ones are ready for delivery. If this will screw up your timetable then maybe there is a 'bird-in-the-hand argument which could be won by an additional discount. AFAICS you hold all the cards at this stage.

Is this a problem over the whole roof, or in discrete areas only? I suspect, given your description, that it is rain blowing up the laps. Although I suggested in another recent thread that sarking felt is not always 'noticeable by its absence' this may be an exposed situation where it would help. It's a bit older than mine, but not much, and I would have little hesitation re-laying at least 60% of my slates as a new roof . I have seen an example in an area of very high industrial pollution where natural slates resembled 'porridge', but if your slates look OK from the top it may well be 'cause they are.

Looks very like it. Try to get rid of the bubbles that are there and do a 'controlled experiment' with significantly smaller amounts of detergent.

Hello! Although the first bit of insulation is always the best one (the graph of insulation efficiency climbs very steeply, and for each subsequent unit flattens out further and further) 100mm on the ceilings is pretty unexciting. The Bldg Regs would require 270mm of 'fluff' (glass-fibre or Rockwool or - as per @Sparrowhawk - recycled plastic bottle insulation ) or a tiny bit less of sheep's wool, recycled cotton, flexi woodfibre etc. I would not recommend lass than 300mm. The stud walls are going to be more tricky for you because of the tight space. My minimum recommendation would normally be full fill of the stud depth, with a wind-tight breathable membrane stapled over the studs. If I could I'd put the same membrane over the ceiling insulation too, to reduce the risk of 'windwash' - cold air getting in among the layers. Are those rafters 150mm? So you could get 100mm in and still have decent ventilation between the felt and the insulation. Access would be easiest if you took the ceiling down. That could, if the pitch is steep and headroom less of an issue, allow you to add further battens and insulation under the rafters. Note the minimum suggested 270mm on the flat ceilings and possibly the 100mm+ to the stud wall may comply with current Bldg Regs. 100mm in the sloping ceilings wouldn't. Normally I advise people to make sure they do, so that on future sale they don't get would-be purchasers trying to push the price down. Others take a different viewpoint. Getting Bldg Regs approval (or not) costs. See Planning Portal for details. @Sparrowhawk has covered the rest re air-tightness and thermal by-pass.

You raise a valid issue, but I'd probably be just as worried about heat-loss via the window-board, unless you have checked and there's 75 - 100mm of PIR insulation in there. Most Oriel windows like this seem to have absolutely zilch that's insulative between the window-board and the outside world. In my experience uPVC window installers don't necessarily tend to be insulation or air-tightness specialists. As far as you can tell, what is actually supporting the window-board (and the whole oriel window structure)?

ps - site currently resembles the Somme ...and sadly probably will do until April+ Is there any scope for a rudimentary 'porch' outside the door (even if it's a free-standing 'shed') so you can have a good doormat and change wellies outside?

... or ask agent to contact the would-be buyer and offer a discount that is more than the cost of re-roofing? My roof has no membrane (and, unlike your friend's mother's house, never has had). I won't say it has never leaked, but at 100+ years old it still requires very little routine maintenance. If I came to sell, however, I am sure the survey would point out the lack of sarking as an 'issue'.

Shrinkage will cause air/w.v leakage through cracks in the plaster layer. Do an excellent VCL on top of excellently-fitted insulation.

Is this clear sheet? How about clear 'Sticks like sh*t'? In my experience it sticks ... jolly well.

All my thoughts as I read the posts so far pre-supposed that you would be dropping the plasterboard and working from below. On the basis that you can't see what you don't see I would not like to guarantee how well you can seal the joints. Variables include rafter pairs which are not a completely consistent distance apart, rafters 'on the twist' and so on. I have never seen a sloping soffit insulation job done 'from the apex void' where it has been completely tight. Even when access is available it's not necessarily wonderful. Many rooms-in-the-roof insulated from above when re-roofing are testament to this. For an excellent job I would kit up with PIR,(if that is your material of choice - others are available - air-tightness tape and a/t primer, bite the bullet, drop the ceilings (sorry!), clear up the mess and insulate the slope leaving a minimum 50mm ventilation gap below the felt. 0versail the sloping insulation past the flat 'loft floor' and carefully detail the junction between PIR and 'fluff'. Are those 150 rafters?

To comply with current regs it should be at least 27cm deep. 40 or even 50cm is not too much for me, as long as you can get access when necessary.

Yes, possible, but as noted by the OP there seems to be air movement in there, so any solution would require designing out unintentional ventilation and designing in the intentional. I suspect the OP was hoping to avoid dropping the ceiling. I'd go the whole hog, but with new 'proper' ventilation designed in.

We bought ours online. My notes tell me it was Floormart.co.uk in Leicester. It was 2 or 3 years ago, but their website says they still do Marmoleum. I thought at first they had delivered the wrong colour, but found on querying it that they had wrapped my roll in a Marmoleum offcut to protect it from damage during delivery. They were v. helpful. I don't know if they have a showroom, but they are not near you anyway. Possibly worth giving them a call.

Is the wiring in contact with that EPS insulation when it 'lies down'? If so you want to sort that. EPS leeches the plasticisers out of PVC cable sheathing. How well-built is that structure? Do you think there is any risk that external air will circulate between the EPS and the OSB at the top of the joists? If so, even if it is a Warm roof (with, say, a minimum of 150 PIR above) the 'Warm' roof element may be doing very little. Edit: Sorry, I had not read @Mr Punter's post. I'd still suggest satisfying yourself re (lack of) air-leakage, though, or the 'by-pass' possibility still applies.

Thanks @sgt_woulds. I was assuming VCL on sub-base and PIR or similar non-breathable ins'n. Good clarification though re WF.