Redbeard

Depends how much your roof void needed the 8. Would be a shame to use 2 and then find that you have a condensation problem in the roof void.

Not the Q, but I am intrigued as to how you will make a permanent, waterproof seal between the vertical glass and the roof glass. Will the roof glass meet the vertical glass via silicone, or will the frame of the roof glass be cleverly rebated so that the glass on each plane rebates into the frame?

'Skeiling' = sloping part of ceiling. Otherwise known as combs or sloping soffits.

Will you be marketing the small ships? Can I put in an advance order?

Is the ceiling already in? Or (hopefully) is the plasterboard still to go on? Have you any pics to show the issue? Membrane, lots of tape and some Passive Purple or similar? Of course stud walls make it more difficult, but unless everything is boarded up, that should not make it impossible. You'll just have to cut and tape around each stud (/top plate if applicable).

Fermacell Fine Surface Treatment, I think it is called. I have only ever used Fermacell once, for a part of IWI to a kitchen where we needed to hang potentially heavy-when-full cupboards on the wall. Instead of 25mm battens over PIR, then plasterboard, we used 25mm ply, then Fermacell, giving us 37mm (? - can't remember F'cell thickness) of hefty stuff (on v long screws) to screw cupbds to. We just had it skimmed in board finish, the same as the surrounding plasterboard.

14 hours ago, Temp said: ...and Sparrowhawk replied: My thought too. If you can hear it as you move, how much flex are you feeling in the floor? As per the OP's description The construction of the flooring is (bottom up): Concrete Plastic Membrane Plywood Laminate (glued down) The 'squidge' appears to be occurring between the concrete and the plastic immediately on top of it. I don't think there is any suggestion that the concrete is moving.

Question from Left Field... Do you have proof that the floor is insulated, as of course it should be? It still does not make great sense since, if it wasn't, the condensation would be on the *top-side *, not the underside, of the plastic, but I am trying to play Devil's advocate so that you ensure that all the variables, however unlikely, have been considered.

How is the knee wall fitted? If it was already there, then after carefully establishing that it was non-load-bearing I would have taken it out, insulated the entire sloping ceiling and then fixed the 'knee wall' (cupboard-front) through it to the (carefully-marked!) rafters. If you did that the wall is entirely 'on the warm side' of the insulation, with insulation above and a habitable room below, and there can be no thermal bridge, as I understand your description.

Both of these firms are in the wrong part(s) of the country but they might be able to signpost you to an 'industry contact': Green Building Store, Golcar and Solarcrest, Macclesfield. I note that GBS's approved installer list includes 2 in 'the South': https://www.greenbuildingstore.co.uk/mvhr-installers/ You might also try RetrofitWorks in London who may be able to give you a contact.

No it wouldn't meet the U value target, but if headroom is at a premium you could argue the toss if yopu needed to, but if Bldg Regs do not apply as it's not 50% or more of the relevant thermal element, arguably just do your best (though personally I would be trying to meet the target). Common practice has been 25mm, and some problems have arisen due to inadequate ventilation. In my view the gov't Best Practice guidance (https://www.gov.uk/government/publications/room-in-roof-insulation-riri-best-practice). Is well-advised. If you decide to go for 25 only then, when you do have the roof replaced, ask for written confirmation from your roofer that the membrane to be used is certified for use with a 25mm ventilation gap (and then check that they actually used that one). It goes without saying that ventilation feeding that gap (the 'ins' and the 'outs' should be checked and confirmed to be sufficient.

Hi, and welcome. I read 'I have suffered from mould exposure and it led to bad health problems, its been hell to be honest. ' as being in a previous house. Am I right? I assumed that because you had suffered before you were anxious to avoid them in the 'new' house. Or am I wrong and we're dealing with an existing known mould problem *in this house*, in which case others' Qs about why the mould is happening are relevant. Can you clarify?

Back to your original post - you said: 'Could I fit 50mm PIR between the rafters and then use 25mm PIR below the rafters before boarding over with soundbloc plasterboard, **then when the breathable membrane is fitted in the future back-fill will another 50mm PIR? Will anything done now be required to meet building regulations**?' (** my emphasis **) If you go now with the 50 between and 25 below you may need BC approval if it is more than 50% of the relevant thermal element (the sloping ceiling) *in the room you are stood in* (Regulation 23 of Part L). As 75mm would not achieve 0.16W/m2K you would have to argue practicability with the BCO. You also cannot automatically assume that you can fully-fill the remaining 50mm rafter depth when you subsequently re-roof. The BEIS retrofit Best Practice guidance for insulation over rooms-in-the-roof says 50mm vent space req'd, common practice since 2010 Bldg Regs has been 25mm, and only a select few membranes claim to be suitable for full-fill unless you are counter-battening on top, effectively putting the ventilation gap *over* the membrane rather than under.

What does the manuf'r say about air gaps on either side (i.e. top and bottom) of the insulation? Can you comply in the space you have? Can you get it air-tight? If it is only stapled, and you cannot get in to get air-tightness tape on then there is a good chance that it will just be something shiny sitting in a breeze.

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.