Redbeard

I'd say get rid of the suspended floor and replace with insulated concrete, or glaspor or whatever you fancy. Reason for this is that I suspect your under-floor cross-ventilation will be sub-optimal and (UFH loops notwithstanding) I would not be certain of the long-term 'health' of your floor. Also what would you do where the pipes must cross joists? I have seen a tendency towards 'over-notching', though it does tend to depend a bit on the age/joist depth.

Check the spec for whatever multifoil you have in mind, as there may be battens required for air-gaps either side, so thin might = 'fat' after all.

You should be able to, but a lot will depend on how the window and the EWI 'interact', and whether the window originally went in from the inside or from outside. Worst-case scenario could be that the inner lintel obstructs the frame coming out inwards, but I think that's unlikely. Even if you had to cut the frame out in bits you could do so with little damage to the EWI with, say, careful use of a reciprocating saw.

Hi, You say 'They'd like them all to be 600mm so they can put storage in'. Do you mean so that they can have 600-wide 'modules'/doors? If so, assuming the eaves are 'cold', how will they insulate the back? Or are the eaves 'warm'? Probably only a structural engineer can respond definitively, but the section of the 'plate on the floor joists' may have a bearing (sorry) in deciding whether one thinks it is load-bearing or not. If you know the size of the purlin there may be some span tables assuming given loads (such as the roof covering) which would give you an idea of whether the purlin is 'doing it all itself' or is being supported by the stud wall (in which case what supports the stud wall? etc. etc.)

Might this help a little as you formulate your thoughts? https://www.nhbcfoundation.org/wp-content/uploads/2016/05/RR10-Full-fill-cavity-wall-insulation.pdf. I can't find any other papers specifically relating to using full fill or not. The only other one I found was w.r.t. 'brick creams'. If we were talking retrofit CWI I would definitely not use mineral wool in an exposed area. Have you thought (subject to prior consultation with potential contractors as to the suitability of their product for use in exposed areas) of building the cavity empty and retrofitting graphite EPS beads?

+1 absolutely re stack - and investigate the flaunching, which is just out of shot. Don't want to be finding that needs doing just after the scaff's come down!

IANAR (I am not a roofer) but a few Qs: Pic 3: Appears to show soakers but no cover flashing... (????) Pic 4 appears to show no cover/tuck-in at the top of the flashing to the parapet. Pic 9/10 - Assume that there are soakers below and that something (??mineral felt?) is covering them. Pic 12 (roof over bay). Not an easy detail, but what is that? Sand and cement? What is underneath/providing a key for the ?sand and cement? to hang in the air? What do the neighbours have?

Lifting the boards need not destroy them. The last floor I insulated from above we punched every single nail down into the joists using a parallel-sided punch. We allowed for 20% wastage (destroyed boards) and finished with less than 10%. It's a b**l-ache, but very doable. It probably took 2 of us half a day for a 32m2 floor to lift the boards.

The cement render may limit the wall's ability to pass water vapour to and fro, and the lime plaster, existing as it probably doesn't (!) behind the skirting boards, may not be wholly airtight. I take your point re Building Regs but I also note the increasing tendency for buyers' solicitors to pick up on any 'failings' (such as not having BC approval for works), note how dreadful this failure is, and then the buyer agrees to overlook the failure if the asking price is reduced by 'x' (where x = an indeterminate number of thousands of pounds). I am sure they may be grateful for the insulation, but potentially even more grateful for the 'cash bonus'. If I can wave a completion cert and avoid this sort of behaviour I will.

Probably a simple Infra Red thermometer would do it. If you run 50-60 degree flow temp those pipes would be hard-pushed to 'hide'.

@Gus Potter, I think you have read this as I first did, that there is a bedroom *over* the garage. However there is no reference to a room over the garage (though there may be one), but to a room *under* the garage, so for that room I think the 'normal' concerns re vapour control are relevant, as the (presumably heated) 'under-room' has a (presumably cold) garage over. OP: Haven't had the thoughts yet as to how to address it, but first call would be a condensation risk analysis (CRA) (preferably dynamic) and an assessment of ventilation. If we pretend for a moment that the ceiling is actually a solid wall, then we would not automatically be looking for a ventilated void if doing internal insulation of an external wall (IWI) (though it would make life easier and would increase the amount of insulation you could use). If IWI 'hard to the wall' is OK, then *some* insulation 'hard to the ceiling (or under the battens) should be OK. The CRA will help you to assess how much.

I would normally advise not to remove plaster (though that applies particularly to lime, and I would normally remove Gypsum) and NOT to use 'pure' dot-and-dab. Preferably full adhesion of the boards, or at very least full perimeter beads with cross-hatchings. If you get air movement behind with D&D you may thermally separate the original wall and the insulation ('thermal by-pass'). With D&D that movement is almost completely unfettered. Removing the plaster (what was advised 40 years ago -along with D&D - when I started IWI) loses you a valuable air-tightness layer. Slim solutions as suggested are unlikely to meet the 0.3W/m2K wall U value target for Bldg Regs. Many would say simply do not apply for B. Regs, but it can potentially come back to bite you when a future purchaser feigns horror at your failure to get approval but agrees to be less horror-struck if you drop the price by £10k. If it is impracticable to meet the target waivers are available.

"As you can see from the photo the wall between and just below the window sill is damp." And above, surely, unless my eyes are faulty. I cannot see below the windows but above seems to be 'blooming' (?moist?). So the chimney ran between the windows and out at the ridge, yes? We need external pics. Faulty verge-work? Faulty/porous brickwork?? More 'base data' please! Then the 'hive mind' will start buzzing. Thanks.

Checking I have got my facts right: This tiny roof void is open all the way from one side to the other (past the porch in the middle, yes? We have already noted that it has ventilation 'in' (at the soffits) but it has no 'out' above that, as it stops on the wall. The only way, then, for that 'in air' to get out is via a 'plenum chamber' at the top of the roof slope against the wall which is open all the way across the whole roof and then exits via soffit vents on the small hips at each end. That way you might actually get adequate cross-ventilation (although I suspect that 'top chamber' might be a little 'under-fed' by the small soffit vents on the hips). You can check cross-sectional areas and I cannot. IIRC it's a C/S area equal to a (some say 15, some say 25) mm slot along the whole length of the eaves. Usual caveats re really tight fitting of the PIR, and v close attention to sealing at jts and perimeters. Air-tight tape and ait-tight foam. (I use Illbruck FM330 as many have mentioned. Expensive but good. (Come to think of it I could maybe apply that to the majority of the materials I use!) Have fun!

I was about to say forget the PIR and go for quilt alone, but that would limit the insulation value at the 'point of the triangle'. You want either a U value of 0.16W/m2K at all points or an average U value of 0.16 for the whole area. You are talking basically 150 PIR and 300 quilt even not allowing for the 'timber fraction' (the proportion of the timber-and-insulation total which is not insulation).

Yes, I heard that too, and have certainly never heard anything to suggest that it's true. Anyone else?

I think there are recent references to Heb Homes on this site.

"The order: 4200x150x50 C24. The delivery: 4800x150x50 C16." A similar thing happened to me. 'Never mind; bring it back and we'll sort it'. Got it all off the roof-rack. Bloke comes round with a stamp, blanks out C16 and stamps C24: Sorted. The explanation, which one has to believe, of course, is that sometimes supply prices are so close that they buy graded (but not stamped) C24 and stamp as C16 or C24 according to the buyer's request. Alternatively they could of course stamp it all C24 and sell it to you for the C16 price!

Switching on my brain I can correct myself here! I must only have had half an eye open not to notice that the porch roof is a hipped roof. So you do have 'ins' and 'out', on the LH and RH sides. Good-sized soffit vents and you are done! I stress'more vents than gut-feeling might suggest' as many builders seem to put c70mm round vents at 1000-1200mm centres. Compare the cross-sectional area of those vents to that of the ideal 'slot' over the entire lgth of eaves and you may be unpleasantly surprised.

Any lean-to roof has a problem in that, ventilation-wise, you have an 'in' and no 'out'. Good cross-ventilation is not ensured, and sometimes cannot be. I am not sure I understand your reference to the 'canopy'. Do you mean the roof to the bay windows. I cannot see from the pic provided whether there is going to be a continuous roof void above the bays from extreme L to extreme R. If there is, and the porch roof connects to it, then there is your 'out'. 'In' via soffit vents (more vents than gut-feeling might suggest) and out via the vents which either already are, or will be provided in the bay windows' roof.

Reading the 'recent posts' panel it reads: Oh Dear Oh Dear Bulb Confusion Oh Dear Oh Dear .... Pocster, what have you done?!

You say the tiles on the front are identical to those on the rear, but the ones on the front don't have a crack straight across, like this (copied from above): Would be really good to see a 'top shot' of that area. Camera, big stick...

+1 to @bassanclan. OK, having seen @Flybywyre's latest pics my presumption ("Can I check what I appear to be seeing? I seem to see a split straight across a slate (slate?), which is mighty unusual.") was wrong. They are obviously concrete tiles (with a different lap pattern) of some sorts. Utterly intrigued by that horizontal gap... Next time you hear a drone flying in the park ask them to take your phone camera up for a spin!

Suggest you follow up ST's point before spending any money to 'fix the leak'. Can you tell us more about the roof? Is it over a habitable space? Is it insulated? If so was the insulation done really well? If it is a Cold Roof (all the insulation below the deck) there should be a clear cross-ventilation path (ideally 50mm minimum) between the top of the insulation and the underside of the deck and (sorry, this is stating the blindingly obvious, but it very often does not happen - you see lots of 'air gaps' without 'ins' and 'outs') it must have 'air in' and 'air out' at opposite ends, unobstructed.

Can I check what I appear to be seeing? I seem to see a split straight across a slate (slate?), which is mighty unusual. I also seem to see a lap pattern which is very unlike the one I laid last year. Yes, we need 'top pictures'. The crack looks quite uniform, suggesting (?? - we need pics!) that it might run all the way across - ??? Would strongly recommend that you do not 'gob it up'. Find the real problem and fix that. Look fwd to seeing the pics - I am intrigued!