saveasteading

Best wishes everyone and esp thanks to the moderators.

Excellent graph thanks. May I ask it's origin? That's for an infinite area or based on some HP/A assumption? Theres a bit of a kink at 100mm ish thickness which seems wierd and that really underlines how worthwhile 100mm is. Severely diminishing returns after, I'd say, 200mm PIR. And no significant benefit after 0.3? ie a complete waste of resources.

I have awarded hearts to people I agree with.... which is contrary to good logic of listening to all views. But my prejudice, or is it exierience and intuition, is that mvhr is grossly over-rated. We build to control air leakage, then pressure test at high pressure with all fans and vents sealed. Then we remove the seals and allow draughts to flow freely from each wc and kitchen. Unless they have automatic shutters but they seem rare. Stuffiness can only raise from habitation, but then the fans are used which draw air from everywhere, to be replaced by whatever leakage there may be. Nobody suffocates. I've only had old draughty houses but the steading (family owned) has no mvhr and has no issues of stuffiness or condensation. I promise to report if that changes. In business I did no homes, but offices, nursing homes and school classrooms* would have the same issues..in all cases we agreed with the client to "chance it" without mvhr.... no problems reported ever. That's x 20 applicable projects at a guess. So I think I'm right. Still listening of course, but we don't intend to fit £20k on mvhr at the current project. * This seems extreme, with 30+ kids in a room. High ceilings help of course but window vents and door openings appear to suffice. Perhaps the teachers open windows sometimes.

Overlap is probably enough, but taping will guarantee it and keep it in place while insulating/screeding.

Cutting. I've just been discussing it with the guy likely to be doing it . He likes the latest and best tools. But for this he says a coarse cut handsaw and a big bench. He is up for the challenge of tiny waste figures if I predraw the best use by room.

Other people are saying that. And I've only ever done small amounts using a handsaw or slicing opposite faces. You've had a lorryload. Presumably not all laid as one area, so you've done it. So any recommendations? What tool? On the floor or a big bench? I think the gross wall perimeter is about 400m. Half of that to cut, x 2 layers. A lot of cutting. So that needs to be efficient and precise. If it's worth buying or hiring the best tool it would be good to know.

But perhaps they haven't. What was their brief?

Thanks all. What have I learned so far? Eps is much easier to handle and cut neatly. As a good fit is a strong benefit this looks like a real plus for it. The unfaced pir appears to be aimed at other uses than construction....keep it in mind for other purposes. I'm reminded that pir shrinks. Perhaps not in an underfloor situation. And it is a pain to cut. Gaps are inevitable, and the double layer, staggered joint, principle is pretty well essential. Factory cuts from one corner for the first layer, then reverse for the second. It's for minor benefit, but why not? AND as the division walls go in, it's apparent that there will be a lot of cutting-in. And that some spaces may be relatively consistent in level so tweaking to an optimum depth isn't so tricky ...perhaps each space will be insulated to the same thickness with any steps being at doors.. I may buy some 25mm eps to make this simple and best value. Waste. I hate waste in principle and in cost. The unused material and then the skip. Perhaps each room needs a plan.... offcuts get taken to where they will fit neatly. Fortunately our workers understand this and our timber waste so far is tiny. I will work it out. Guessing 2%.

10 year return would be my judgement, if that fits your advice. The "very best" implies value for money by my way of thinking. Eg passivhaus to me isn't the best, but a benchmark that is admirable but seldom the best thing to do measured by money or carbon.

It's been interesting to follow how strongly you are making this argument. I think you are wrong, and have even started sympathising with the other party. Reasonable care is judged by what skills they may be expected to have. In this case that would not apply to knowing all the building regs, esp as they apply to an existing property, and whether they are expected to write a long list of exclusions. But the credit card company may decide on some other logic. So I've no more to say.

Of course. But that 50 % is off a published list price for a few boards. My estimates will always assume expert buying. I'm assuming both, with the rest from waste control, optimising the design, detailing. And minimal skip cost....or have you a secret of using offcuts? 50 +20.% Almost free! Actually this is the one area where my estimate seems high. I'll report back when decisions are made...this isn't going in for about 8 weeks. Any more experience of the unfaced stuff from anyone? My instinct too. So prob the 150mm goes down as 2 x 75, on dpm, and following whatever dips and ridges. Then tape and dpm. The 'ponds' can be reassessed for 25mm boards or screed and I'm tending towards just screed it. PIR at about £80/m3 and add tape and labour. Screed material I'm only guessing at £150/m3???? Extra labour about 15 minutes. Ahhh. Best do a level survey.

I'd be surprised if an arbitrator or similar deemed a window installer should have these skills. Unless they advertise.. 'more than a window company' sort of thing. If you'd gone through a general contractor then this might be different, but you'd have paid a lot more.

Yes.

That's arranged. But on site so he can see the vast amount already from them and the future scope. And he can go away with some homework. Interesting about the stocks. The cost £/m3 seems to be in just 2 bands. 25mm to 50mm is dearer. Above that it is nearly identical whatever thickness as if the foil had no value. But the local merchant buying in a whole load of one size would get them a good price so I'll look I to that. Another benefit would be phased delivery. When we need it and less handling. And we can order just enough and a few more later if needed. I'm thinking 5% waste....any thoughts? Faffing is what I do. Efficient, holistic design, negligible waste but without stinting on quality. If I can make £1,000 by faffing I will do so. Or put another way: 20% saving on materials: imagine that on the whole project. The floor insulation value with 150mm of whatever on 150 concrete and HP/A of 0.1 gives us plenty and I'll take the cash now thanks.

I would say that tape or staples are a temporary fix but a sensible way to prrp and tidy for now. Is there a designed detail?

You might simply be able to push up the elbow to stop the leak. I'd repair the bigger holes ASAP. A pointing tool is a good investment and disguises my amateur work.

You've given away the secret of good design. Water droplets, units of force, whatever. Then express it on site in dance.

Interesting I looked it up and suspect this will be your problem copies of warranties, photographic evidence or independent expert reports, for example. as I expect your bank will immediately ask for this and you will be into costs. alternatively the other party will throw some tech explanation at the bank, and then they ask you. OTOH if the window people do think they have some liability, or better things to do with their time, you may get an offer to end the matter.

Hadn't thought of that. Just how soft / fragile is it? what about handling it? But the cost difference appears to be £1,000 maybe more if in 2 layers. There will be lots of cutting as the rooms are divided. But that would help in defining areas and promptly covering in polythene.

We will have 150mm of insulation under a 60mm, or so, screed. I'm looking at costs and practicalities. the existing slab has a variation of 30mm in level and is about 18m x 18m. 150mm to 180mm of insulation is preferable in performance and cost to making the difference up in screed. I'd prefer 2 x 75mm thickness to allow overlaps, with the top face taped. Then add 25mm where necessary but perhaps 1 x 100 everywhere and a top layer of 50 or 75 as appropriate. dpc and/or tape over steps may be tricky. I started off considering PIR to the top and EPS to the bottom for economy. On the basis that EPS is half as good and half the cost. But as we have an exceptional HP/A, the centre of the building isn't going to lose much heat downwards. And, as previously discussed on here, the performance is not linear and insulation diminishes with thickness. Listed costs for PIR are very similar on some sites (who will match each other) with others a lot dearer (but will match) so I'm using these for the exercise. I'm optimistic the area will encourage a discount. The sites quote different delivery charges at surprisingly small sums (order of £150ish) so their target buyer appears to be for small works, As such, EPS is half the cost for thin boards but 2/3 for thicker boards. But assuming half price, the saving is £1,100. The Seconds company seem to be the only supplier of unfaced boards. That can't be so? It is much cheaper and matches the eps prices. There is no benefit from a foil facing in the dark with no air spaces. Or is there strength or the tape sticks better? Seconds quote thicknesses as eg 90-100mm or 140-150mm. Does this imply that most of the product has been rejected for being too thin? Or maybe some is thin, and they don't know what will turn up, so this is sensible advice. But what do I order if I dont know the actual thicknesses. Maybe they can tell me at the time. I'd like, as always, to support local merchants rather than distance. so am hoping they can match these prices. maybe they can source seconds when requested. I wonder if it would be double handled at the yard or come direct from the factory. Any thoughts and experiences welcomed, both science and site, as are questions.

and French drains leading to them. Once the amount of storage is assessed you will know whether a controlled overflow is a good plan. I guess you could reverse this, with water to pond/rain garden and overflow to soakaway.

I'd scrape the loose paint off to help it dry inwards and also to monitor it. You might find the the plaster beneath shows dampness, and I would mark that in pencil and be delighted to notice that it isn't spreading and may be reducing. Will you be doing diy ? Anyway you can brush off the green stuff now, as that is holding water. this is one of those queries where we can all feel good at sorting an issue so please repot back for better or worse.

Quite so. I'd advise you listen to the advice here. it may be free and we aren't always right, but it is by people who have done it/ do it for a living/ know the theory or the reality or both. Draughts are worse than cold bridges and that thermal pic may make it look worse than it is. draughts can be sorted with standard brush strips. so what do you do if you get awarded £30 towards fitting these? Up to you. You will spend many hundreds and they might agree that it isn't a justifiable claim. I've sat with an industry expert (selected by my solicitor) because of a cost claim by a client. I think it was about structural design. After a very expensive hour he said how interesting it had been, and I clearly knew more than him on the matter in question. That might be the case here, with the free advice above being equally expert. Not mine: the others who know this subject backwards.

Yes. Depending on your topography you could have a lagoon and rain garden . this then works as a soakaway but also loses water through evaporation and from transpiration of any plants. In the winter it doesn't work so well though. so it has to be big, and you must be prepared for it to dry out in summer. any rain will disappear before reaching it (see 'French drains' later) . I discussed this with a Naturalist, and he agreed with me that nature finds a balance and it isn't for us to save every creature from the drying or flooding cycling. BUT I had the feed drains built as French drains so that only overflows from them reached the lagoon. also rainwater harvester inline. It worked well for 1000m2 of roof. The planners and the LA 'nature' advisors resisted at first because it didn't fit with their hierarchy of solutions*, but I convinced them. So yes, but don't count on approval. * they have lists and like to see 'things'. so they wanted a green roof and crates. I explained how this prevented the water from reaching the harvester, and added tonnes of steel (so carbon) to support it. You do still need the water to soak away. Is it perched water? unlikely I think. Otherwise you would have seen it running from the sides of the hole even as you dug it. Was the ground you dug pretty well saturated? It may simply have been oozing from there. Your percolation test is decent and that is what matters. A crate will fill with water and so provide a head of water which will head downwards. You appear to have space, otherwise a rain garden wouldn't be a consideration, so you can have a bigger area of 200mm deep crates. OR simply do the drainage field principle as in the building regs. Caution: if your rain garden or lagoon overfills, where does it go next?

the photo is helpful. I suspect a leak from the lower downpipe joints. Notice how the green is spreading out from that.