Redbeard

I realise complexity makes £/m2 costs a bit meaningless, but my GBS (21 Degrees) 3G wins came out at about £735/m2 supply only in 2022/23. (Tried to send you a PM re another firm but apparently you cannot receive messages...)

I fear wood-fibre etc. *will* 'break the bank', at least compared to the costs of PIR. Don't get me wrong, it is exactly what I propose to use in the refurb of my rooms-in-the-roof, but mine is a steep-pitched roof with plenty of headroom. My 'sandwich' is proposed to be: 20mm rigid WF (lambda 0.044W/mK) between 75mm rafters leaving the recommended 50mm (well, 55 here, but Gov't guidance says 50) ventilation path. 225mm flexi WF (lambda 0.039W/mK) in Larsen Trusses, and 20mm WF again as plaster carrier. This sounds like it would take a lot of space which you have not got, and it *will* cost plenty. For me this is the right thing to do and I will shut my eyes and scrimp on other things to achieve it. Unless you use PIR (and I am certainly not trying to persuade you to) even your +5" on top will not get you a compliant U value. There are some get-out clauses in the Regs. See pp 25 and 26 of 'Part L': https://assets.publishing.service.gov.uk/media/662a2e3e55e1582b6ca7e592/Approved_Document_L__Conservation_of_fuel_and_power__Volume_1_Dwellings__2021_edition_incorporating_2023_amendments.pdf And try to get a word with a Building Control officer. Depending on staffing levels they can be hard to pin down, but as well as ensuring compliance with the regs they also have to be realists. I think if you are trying to get an area-weighted U value of 0.15 with such limited space in or under the rafters you might find that you are trying to get more insulation in the eaves voids than they will physically contain! Fairly certain Planning permission would be required to lift the roof but, importantly, if you are using WF or similar, 5" will not be enough - see my lay-up referred to above. Also, as Warm roofs are typically done with rigid material, the weight of rigid WF @ 140-180kg/m3 would, I think, break your roof! Flexi is, I think, about 55kg/m3. I am running out of stamina tonight but have a look at this and fire back further Q's and I'll try to help if I can.

When you say 'running out' I take it you mean running downhill to the dormer cheek. Am I right? I can see that )possibly) on the 1st pic (RHS) but not sure if I can see it on LHS, or whether I am just convincing myself I can! I am generally fairly pernickety, and I would not, I think, have picked up on that. How often will you stand and look at it? If it will annoy you forever, change it. If you can programme your eyes and brain to 'ignore', live with it. Ah, I have just read again and seen: Hmm, maybe my advice above won't help then. I *suppose* you could basically eye it up, decide on what would look right to you, decide the adjustment required for the eaves course, alter the battens accordingly and go from there. I cannot think of a more 'scientific' way. If that helps a little, good. If it doesn't, sorry.

If you are really 'taking off the roof' why not try to get a structural design which includes removing that cross-timber and providing alternative strengthening? Have you got a structural engineer? Have you been through Building Control? Is Planning Permission required?

BC won't like it, nor will they like the fact that you are not using permeable paving, I think. Are you getting Planning Permission? Has the would-be contractor done a percolation test? If a soakaway does not soakaway it's just called a. And it can also soak away too fast. That's not good (or allowed, I think)

What for? Footings, lintels etc. @Tony L, did you not need a structural engineer? A long time ago the architects I worked with did their own SE, but from quite a long while ago they started using consultant SEs.

AFAIK this is now out of date. (Yeah; checked it!): "28 Feb 2023 — England and Wales both introduced new building regulations that tightened the limiting air permeability for new buildings from 10 m3/hr.m2 to 8 m3/hr.m2". (www.partel.co.uk) I am pretty sure it is 8m3/m2/hr (@50 pa) now. (p.a. is per annum and should not be there!!)

I am not sure it would (though there is probably not a requirement for scaffolding to be metal -I have no idea). However occasionally you'll see a scaff self-erected by a (building, not scaffold) contractor which looks, frankly, frightening.

Well... the louvred covers with loose flaps gives some back-draught protection but if the wind is in the wrong direction they flap and chatter like nobody's business. I swapped them for cowls with a 100mm flap which, being 'sheltered from the wind', does not 'chatter'.

I have one of these. Pretty enough but there's no back-draught prevention.

Have you tried Ecology?

Really? I realise that's glazing only but even that seems low if it's a 28mm unit. Is it, or have they used a smaller bead to give you a bigger rebate? (I know you can do that with Rehau 'double glazing' frames, up to as wide as 44mm - although someone from GBF who has done so said the tiny bead is a real bu**er to get in and out).

+1 to that.

Excellent. Sounds like 2 hops forward!

OK, it's a long way away but depending on the distance between where you'd connect and the main sewer I wonder if your water authority would accept the ditch as, in affect, a linear 'leach-field' (attenuation 'device')? Suppose it depends a lot on whether the clay persists at the same level for the entire run of the ditch.

You need a structural eng'r too, else your Bldg Regs application will get stuck when they ask for proof.

Get them made to your Structural Engineer's own design. Yes, not every steel fabricator will do stainless, but some will.

1. Could well be, depending on whether you are expecting them to do just dwgs, or dwgs & spec, or dwgs, spec and site supervision. Check they are fully experienced for the 'package' you want. 2. Maybe. I effectively 'drew' mine, but gave them to someone to 'computerise'. Sub out the SAP, again, preferably to someone who knows the building physics as well as how to drive the software. 3. Absolutely no idea! Sorry.

It's a very non-scientific 'diagnosis' but if you look at the shape of the left-hand-side of the empty footing trench the crack seems roughly to follow that shape, suggesting that the crack is between the existing (pre-extension) ground and the (presumably softer, less compacted) fill.

Given that it appears to be smeared with sand/cement could this perhaps be a (modern) fibre cement verge trim? I used one 2 years ago. If you think it could be a heck of a lot older (say no later than 2000) there's a possibility it could contain asbestos. When you say do you mean had the whole roof re-laid? If so, unless someone had some very, very old stock, I think you can be pretty sure it is not asbestos-bearing. If in any doubt whatsoever get a sample tested.

I suspect we won't get anywhere nearer answering your question till you explain more clearly what you wish to achieve by carrying out the work. Obviously without any dimensions, or details as requested by @saveasteading I can only guess what you hope to achieve. The tie-beam cuts across the space, but how big is the space overall? What proportion of the available space is on either side of the tie? What is the height at various points? What size are the joists? Often loft joists are 75mm deep while (depending on the span) joists for a room could need to be 200, 225 or more (but none of us can know without more detail). Where would the stairs be? The only way I could see of it being acceptable to BC is if you converted the largest space on one side of the beam with the rest left as void or subject to approval) storage. If the use of the room involved wriggling under the beam what would be the effects on emergency egress, in case of fire, say? You said How will you 'remove later when we can construct supporting structure' and why can't you do that in the first place? And have you asked this question directly of your local Building Control dept.? Lots more details, please, and then we may be able to help.

I suspect that makes the LA a 'successor in title' to the County Council and could (I am guessing) make it tricky to argue that the covenant is no longer valid because neither party exists. Unless it said something to the effect of 'for the lifetime of either party'. But I am not a lawyer! I agree with @WisteriaMews. See what a solicitor thinks.

Congratulations!

Well... It would be good to have membrane 50mm or so below the top surface of the aggregate, not least so that (if the sheet of membrane is separate to that (which isn't!) under the main gravel area) you can every x years, lift up the membrane, dump the gravel (it's a bit coarse for 'gravel') in a bucket, washout the 'fines' which are your enemy in this instance and start again with a new sheet of membrane. Whether it will clog up depends to some extent on the ingress of fines (you have no membrane at the moment to stop this), and on the extent to which it actually becomes a drain - the likely flow, which I read as potentially quite low (but I may be wrong). With the addition of a membrane near the top, but without a 'sock' it will be no worse than many older FDs. I had reason to query the efficacy of the membrane I bought, which is the typical (quite cheap) woven black stuff. It is almost completely impermeable, so if your 'sock' is made of that it could stop the water getting into your pipe! On the other hand I recently saw a test on Terram (other makes are, I am sure, available) permeable membrane, and it undoubtedly IS permeable! It is also a great deal more expensive, but I was glad it was being used for the (permeable paving) job in question. If the wrong membrane had been used then the 'reservoir' of no-fines coarse limestone below the blocks would have had a lot of difficulty working. In your shoes I think I would to the 'over the top' membrane as above, find a couple of points where I could in future get into the pipe, and wait and see, including having a look at the outlet when it's persisting down to see if it's actually working as an FD at all.

+1 to @Conor's answer. I am not aware that the physical appearance of later 'non-asbestos-cement slates' differed at all from AC 'slates', so get a sample tested. Usual precautions when taking the sample, but then lots of 'mail order' services available. In the past I used to get an asbestos surveyor out to take the sample and send it for testing. This removed me from the equation and in my view, from the point of view of PPE, (see my username!) was worth paying for.