Redbeard

Have you already looked at this? - https://www.planningportal.co.uk/permission/common-projects/roof/roof-planning-permission Well done for getting rid of horrible concrete tiles and reintroducing slates to a house built with them! New Welsh? (Unless you live in Cumbria, perhaps)

Am I wrong in having understood that there is no part above the roof? I thought there was a pic in the other thread of the flues ending at loft floor level.

If your cavity is filled the critical risk area could be the inside of the outer cavity skin, though as @joe90 said it depends how the cavity interacts with the flues. However if the insulation in the flues is 2x that in the cavity the inner skin could also be at risk. A WUFI condensation risk analysis, while costing a fair bit, might put your mind at rest.

The Permitted Dev'p't conditions say: '' No outbuilding on land forward of a wall forming the principal elevation. Outbuildings and garages to be single storey with maximum eaves height of 2.5 metres and maximum overall height of four metres with a dual pitched roof or three metres for any other roof." I don't think we can see your (house's) principal elevation from those pics, can we? If your house is in the 'invisible foreground' of pic one then surely the principal elevation is at 90 degrees to the front of the garage, and therefore surely the garage is not in front of it... (I think...!)

By the way, is your cavity wall (I think the other thread said you have a cavity wall) insulated? If it is not, is it vented? If the latter, that would further reduce any potential issues in the flue. Looks like @joe90 and I are sharing the same 2 pennies!

Perhaps a v 'tight' coat of plaster (I would use lime, as I like it) for the Compriband to 'bear' on?

Can we have a sketch or anonymised pics, please?

OK, others will no doubt comment too, but here's my 2 penn'orth: Back in the days of DIY guides to home improvement the suggestion was that you *always* ventilated unused flues, so you were advised to insert a vent in any rooms which once had a fireplace. So, that gives us warm, moist air from a living environment being pushed into flues which get colder as they get towards the cold roof, bringing with it the risk of condensation. Your flues no longer run out of the roof, but to the ventilated roof void, so if you decide to leave the whole lot open you *may* be OK, whereas if you leave the top open and close the bottom you have closed off the ventilation anyway, with the PIR at the bottom and the EPS in the flues. I suspect that in your *particular* situation ventilation of the flues could be irrelevant. Can't comment on 5 as we do not know all the myriad specifics of your house, but if the *before* status is a situation which sucks heat out of the room and the *after* status is one which doesn't then I'd say you have a recipe for a good outcome. All other shades of opinion welcome. *Note that any filling of existing flues with any sort of insulant is regarded as 'experimental' (hence my suggestion of the 'dump valve' for checking).*

Block at the bottom, perhaps with PIR (and air-tight foam and air-tightness/vapour-tight tape) as suggested in the other thread. Backfill with EPS beads. Seal at the top the same as below. There is some risk of interstitial condensation on the skin which is external but careful attention to air- and vapour-tightness should mitigate that to an extent. I cannot remember; can you get your head in to look *down* the flues? If so, you could always engineer an airtight 'dump-valve' in the bottom to allow you to let out some or all of the beads so that you could check for dryness inside the flue at the top end. (If any of the chimney breast is un-plastered (above the bedroom ceilings, for example) you could roughly plaster it to prevent (moist) air ingress.

To be fair I'd have read 'animal waste discharged....' as 'animal waste *is* discharged...'. Along with the previous and subsequent items it seems to read as a list. I think all you need to do is clarify in writing that it was meant to say/mean 'used to be discharged in the distant past. For the avoidance of doubt there is not, and will not be, any animal waste on site.' Or summat like that, and I see no reason why you should not write to the consultee, cc the LPA.

Have you read the gov't's guide to the PWA? https://www.gov.uk/government/publications/preventing-and-resolving-disputes-in-relation-to-party-walls/the-party-wall-etc-act-1996-explanatory-booklet This may (or, I accept, may not) answer your Qs. (Was typing the above when @joe90 replied). If your new retaining wall is entirely separate from the party wall and will not in any way interfere with that wall's foundation you *may* be able to argue that these are not works to, or affecting, a party wall. But I am not sure we have enough info. It seems that the party wall is built well above the level of your yard with its footing well above the level of your yard, possibly meaning that if you were to take down your 'retaining wall' which is entirely on your land you would be removing support from the party wall. That sounds like something which affects a party wall.

I don't know the Permitted Dev'p't rules in Scotland, but I do know that you could construct a timber-framed garden room and achieve far, far better insulation and air-tightness standards than a bog-standard static caravan. Yes, you can improve upon the 'standard standards' of a caravan, but as that would effectively involve building a better-insulated structure around it, surely better to build that structure without the impediment of a caravan...

Yes I don't know, because I do not know what the designer had in mind. One assumes either that it is an incomplete dwg - there is nothing shown above the firrings - or, as you surmise, the OSB is in the wrong place. I always like a howling gale on the top side of a cold roof, although I have seen designs for apparently unventilated, fully-Warmcel-filled roofs, which seem to work OK. As that is drawn I cannot tell whether the 'air gap' has ins and outs (cross-ventilation) anyway. Has the detail been drawn by a company specialising in Warmcel-ins'd roofs? Warm roofs are theoretically much better, I feel, but the scope for poor execution due to misunderstanding the concept can be significant. If you get someone who is really good at insulated cold flat roofs you *may* get a better job than asking them to do a warm roof that they have never done before. Is it really a full-depth thermal bridge, or is the tail of the arrow masking a 'mitigating' piece of insulation? Certainly it wants to be 'cloaked' as best it can.

Can you offer some clarification, as the pictures and the words seem to say different things to me? I don't understand Where is the boundary line on that pic? Are the garage roofs in the foreground (Green Mineral felt)? What is the sloping mineral felt roof - is that part of the neighbour's garage, or of yours, or of something else? I cannot see an obvious 300mm gap, but maybe it's just the camera angle. Is the gap you are talking about on the L of the lead flashing, just past the brickwork return on the taller building element? Assuming the garages are not new, are you saying that there has never been a 'rainwater strategy' up to now other tan it falling off the edge? How long has that been the case for?

+1 to Gloomsbury! Wonderful belly-laugh sort of humour.

I cannot see how deep any 'dinges' are but if it were me I'd be tempted to try a bag or 2 of thin-coat EWI-type render. Goes on easily (you can use a toothed trowel as a depth guide if you want, and effectively do it in 2 'half-coats'). Let the first half stiffen up a little then 'fill in the valleys'.

What's the round thing we can see at the bottom? You'd expect a side, not a bottom entry, but wd be nice to know what it is. It is perhaps likely that if you cannot find an inflow and outflow pipe that it is redundant, but although we are perhaps assuming that that is the invert (bottom) that we can see, are we sure? We had the Water Authority out to one, which they declared redundant. They were interested. Did you ask your water auth'y if they would visit? Yes, they don't maintain it, but that need not necessarily mean it has nothing to do with drainage. No-one can really confirm anything based on that pic, I think. The lack of any 'ins' and 'outs' suggests it is not used/cannot be 'live' *as mains drainage*, but that's only a suggestion from afar!

Yes...

I worry about those puppies! Maybe that's where the dog('s)-leg comes in...

+1 to @joe90. It worked for me. You have to be OK with the admin, but it can be kept v simple. I only ever used spreadsheets, not 'accounts packages'. Only difference to @joe90's sugg'n is that my prices were always stated to be estimates, not quotes. Not that the customer necessarily sees the difference, but if unforeseen complication leads to a higher end-price you can point back to 'estimate'. In reality, reasonably often my final bill was less than the estimate.

Although you have highlighted (?highlit?) the area the pic is not clear enough for me to see what the issue is which you are referring to. Perhaps the top-coat/paint has flaked off the render at the jct with the tiles. Is that what you mean?

Ideally you want a dynamic condensation risk assessment such as WUFI. This will tell you whether the added insulation will make the plank/membrane 'interface' cold enough for condensation to occur in worst-case circs. A 'rule of thumb' (which seems sensible but I cannot prove or disprove) is that if you do mix insulation between and above the rafters then two-thirds of the R value should be above the rafters and a max of one-third below. If my quick maths when I saw your post last night was correct that's a max of 100 -110mm of, for example, flexi wood-fibre with a lambda value of 0.039W/mK. Your glass wool may have a lambda value of 0.044, so a bit more thickness may be OK. But definitely using WUFI to 'prove' it is the better path.

Via the trickle vents and undercuts referred to. The dMEV units are the extract/'pull' which pull fresh air in via the trickle vents.

Not quite an answer to your Q but I always try to achieve more-or-less the same U value for all elements of rooms-in-roofs, so never mind that stud *walls* only need 0.3. I look to achieve 0.16 or less over the entire envelope (apart from the windows which are not very see-through at 0.16!)

That was my first thought, and if it's the sort of thing I have in mind (and had a few years of schooling in) I would have some doubt as to how it would stand up to a rigorous structural assessment. I take it you have already done a trawl through the local SEs? While you may not find someone who specialises in timber buildings (and old ones at that) a generalist with a portfolio including timber buildings and an interest in a challenge might be prepared at least to have an initial look. I like the idea of pulling the 'Local Charity' strings and looking for pro bono or reduced fee work as well.