Redbeard

Rubber Plastic? Are you thinking of sandwiching a membrane in there?

I feel there must be too much risk of distortion with 5m 'unrestrained' (except by the glass, and that does not really want to be a stressed member, I feel). I wondered about making it as 2 units, one with a 'transom' at 2.5m and the side members sailing past that transom by say 300mm. The 2nd section has only bottom member and the 2 side members. Cut stopped pegged scarf joints on each (very easy to say...). With very accurate joinery it would look lovely, and the transom can be a 'spindly' as you like, as long as it can accommodate 2 rebates, so perhaps 60 as against the 90 mentioned by @fatgus

Ah, That's why your archo has misgivings. The flexi WF is about 20kg/m3 heavier than PIR. However, get a SE to appraise the plans. I have similar plans and my SE has just OK'd my roof for the additional load. Structure is not wildly dissimilar to yours but significantly steeper pitch and bigger purlins. (but mine will have a bit more flexi WF and circa 5mm lime plaster, not 50mm Diathonite) But hang on, that lay-up looks unusual. From the pic I had taken the rafters to be 75mm. However the spec says 100 between rafters, so I guess they must be 100! However no ventilation gap, and I cannot quite understand the breather membrane as an 'interstitial' layer.

Roughly 1 litre of water given off for each litre of gas burned. Even if you don't succumb to the CO poisoning you won't help the moisture situation. +1 to elec.

What I'd do if it were mine: Can you excavate and (at least temporarily) expose that wall? Do that, bubble-membrane with good detailing and back-fill with large aggregate ensuring lots of voids and you'll have good drainage around that area. Now you can hack off the tanking slurry and plaster in lime (which I like) or gypsum (which I don't, much). Any contaminants in the blocks will probably leach through lime as much as gypsum. Lime is good; I really like it, but it is not a universal panacea for moist walls.

I have seen examples with a 25mm gap and no problems. I have also seen horrendous condensation and mould on breathable membranes with a 25mm gap (and admittedly some other poor practice too). The Gov't Best Practice Guidance for rooms-in-roof says 50 (https://assets.publishing.service.gov.uk/media/61d727d18fa8f50594b59305/retrofit-room-in-roof-insulation-best-practice.pdf) and that seems to me to be a good a**e-covering 'belt and braces' (to mix my metaphors).

My bathroom was insulated over 35 years ago with 'Styroliner' (XPS and 9mm - 'standard' - pl'board). No special treatment - painted with vinyl silk. Still absolutely fine.

£6k! In post 1 you referred to it costing her £6. Had the 'k' gone astray? This sounds horrendous if the 'k' is right. I assume the lady did not go in the loft and that, if one were feeling cynical, the pics could be of anywhere? On the other hand re the respiratory issues and the 'warm feeling' it sounds like something must have been done...

Expanded metal mesh, galvanised if you have normal-depth pockets or stainless steel if you are rich! I used lime over galvanised expamet 16 years ago and nothing has fallen off!

Good Qs, @Iceverge. @deuce22, you had said: " Merely so my mental picture can be complete, are those boards there? You had referred to this as a warm roof. Strictly it's a hybrid warm roof, as (in my view) it is generally accepted that a Warm Roof has all the insulation above the roof structure. Precautions need to apply where some of the insulation is above the rafters and some between, lest the 'between' insulation should cool the 'interface' (the boards or 'not-boards' referred to above) between itself and the insulation above the rafters. Has an interstitial condensation risk assessment been done on this basis? If a CRA has not been done then a 'rule-of-thumb' from a highly-respected colleague is that two-thirds of the R value should be over the rafters and on-third between. (Reverse that, for example and the interface gets potentially too cool). Taking PIR as 0.022W/mK lambda value the R value of the PIR is 6.81m2K/W. Min wool lambda values vary but if we take a worst-case at 0.044W/mK that gives us an R value of 3.41m2K/W BUT we have rafters 'interrupting, which I am not calculating at this point. With no real justification let's say the 'timber fraction' lowers the R value to 3.0. That about fits the rule of thumb, but there's still the outstanding question-mark - the subject of your thread - vapour control. @Firsttimer I like the dropped ceiling idea. Still needs excellent attention to detail on the VCL above, though - a job for an obsessive! Even the fixings of the dropped ceiling become potentially-leaky penetrations.

How 'very' is 'very'? Have you had a test? You say So is the stuffiness in the bedroom happening even with dMEV running and trickle vent(s?) in that room open?

Wow! Think I'd be fed up too! I regret my patented (not) 'Spotlight condom' does not exist (though I think it should!). However Partel make this: https://www.partel.co.uk/product/airtight-downlight-cover/ which might work (???) (Actually, now I have looked at it I don't think it would work, as it's obviously made to sit down on a ceiling, whereas your lights will, I think, be pushed up into holes in the ceiling). I feel you are going to have to fabricate a version of the 'spotlight Condom' which can be fitted with a/t tape from below and then pushed up with the spotlight.

Not easily, no, if I follow your description correctly. I assume the ceiling is not up yet, although the 'lots of spots.. etc' seems to imply otherwise, since you need a ceiling to fit the spotlights in. If the ceiling is not in you could *hope* to achieve vapour-tightness IF you can get vapour-tight shrouds for every 'intrusion'. This will effectively be a 'spotlight condom' with a grommet to fir tightly over the cable. And remember that if you pull an EPDM grommet over more than one cable it will not be air- or vapour-tight. 2 wires, 2 grommets. I hope you can make it work.

I got confused re this, but assume that in this sentence 'cork' should actually be 'core'??

This is UW (while unit U value - good, as it includes everything) not Ug (centre-pane U value - less good, for obvious reasons), is it? I have some scepticism re alu windows and doors but they are undoubtedly a lot better than the old 1970's and 1980's non-thermally-broken ones. I was pretty surprised to see how 'vestigial' the 'thermal break' was on one set of alu windows but (after a bit of a shock when the new-build was still pretty 'moist' and the windows were pouring with condensation) they seemed to 'settle down'.

...with the mansard section, do you mean? Is the lead new, or is that what was there before. If the latter then I doubt the new roofers have got it wrong, and if the lead is new I would imagine they would simply have replicated what was there before. No obvious reason to worry, I should have thought, but that's from an assumption that it's a fair roofer, not from anything the pics show (or don't).

Urghhh! If the only problem they have left you with is a scrappy sticky-out membrane then it is arguably just an aesthetic consideration, but it does make you wonder whether they have done anything else 'non-standard'. At least there is an iron on the end of the hip.

Sorry to hear of your problems. How about phoning or writing to RIBA (Royal Institute of British Architects) and ARB (Architects' Registration Board), explaining the paternity leave matter and ask them if that is normal behaviour. What explanation was given to you for the charge? Presumably that hours were taken in effecting the transfer of work, but if your contract is for provision of a service then it should not matter who does it, and if they have to faff around behind the scenes because of personnel issues that should surely not be a problem you should have to *pay*' for...?

Are you expecting it to pick up much water? (Does the path fall towards it, for example?). I have incorporated a perforated pipe, with the gravel over it, (and a drain connection at the end) at the base of my EWI.

It is hard to come up with possible answers without fully understanding the construction, but I'll make a guess that the top of the offshot gable/boundary wall (where you need the gutter particularly) is 'capped' with the metal detail, with a 'downstand' down the wall as shown and, presumably, and 'upstand' behind the vertical sheeting. I would be asking myself 'how easily could the vertical sheeting come off so that the 'downstand/upstand detail' I described (however badly!) could be replaced by an 'upstand/upstand' detail, basically a wide gutter, which sits on top of the wall where the existing detail sits?'. So you said: I think that if what you describe as the 'ledge' is what I describe as the 'upstand/downstand detail' then it's not about sitting a gutter on top - it's about replacing one with the other. In terms of liability how tight were the stipulations in the design/contract? Was it 'positive performance-led', insofar as 'it must do this and that'? Were there any negatives - 'It must not do that', for example where 'that' may be tipping water down your wall and onto the heads of the neighbours. And who designed the 'metal top'? Contractor's designer or your architect? Somehow the issue of liability needs to be raised with all parties. Plainly what you have (though it looks quite nice!) is not performing properly. I quite understand your neighbours not wanting to agree to an 'aerial trespass' (no, I am sure that does not exist in so many words, but I hope you know what I mean)

Hello. Your penultimate pic appears to be an earlier one with a red line added, but no apparent explanation of the red line. Is it meant to say 'should this have been a gutter with a fall-pipe at the RH end?'. In which case 'yes. You seem to refer to this wall as the 'party wall'. I can see it appears to be the boundary, but then (single-storey, I assume) bldg at the bottom appears to be a garage. Does it share that wall? Seems to me there ought to be gutters at the bottom of the metal cladding all round. I cannot read the pics too well but it looks at if the builder has assumed that if it's in line it's all one wall and does not need a gutter. I think the different behaviour of the 2 materials - one completely impervious with no 'buffering' and one (the brickwork) somewhat absorbent and thus 'buffering' - means a gutter is necessary. I cannot see enough to know that this would solve all your problems.

Thanks @Ferdinand, that makes sense!

Hi Lewis, It would certainly help me greatly (and probably others too) if you defined the types of social relation(s?) you mean, rather than having to open the file to find out. Is that possible? (By the way, I have just received a request to take part in another survey and I cannot read the pro forma to see if it's for me or not, since I cannot get past each page without filling it in! If yours is like this it may put people off starting. Hopefully it's not!)

What about pre-fabricated straw panels? "If you’d like to get in touch with Barbara about consultancy, EcoCocon’s prefabricated panels, or anything else, you can email her at barbara@strawbuilding.org.uk or contact her by phone on 07720 716 589."

Cork board, perhaps? Or perhaps not is low cost is a criterion.