saveasteading

Per board or m2? At present my best price for 100mm white eps is just over £15/ board of 2.4 x 1.2.

Depends on the "STUFF". If it's a 1mm sheet of metal then water and air will get through so special screws have special washers that bind to the thread. A screw into timber might allow damp but not air through...so perhaps a smear of mastic is worthwhile. Yes through wood has been compressed so is tight, but could get damp. If you look at screws into cedar you can see that damp has got in.

It's BASF so not likely to be untrue. I've found a thing saying the eps nodules work identically, being bubbles of air, but the conduction route over the bubbles' convoluted path is less conductive because infra red gets mirrored back whence it came. Hmmm. Anyway its quoted insulation is 10 % better than white eps, but I think the publushed cost is double, and I wouldn't expect so much discount.

I'd have to check the facts but I recall that there was more than one factor, one being that a fire test sample was 'adapted' to perform better.

I wonder if it is hyped the same way as Multifoil, ie tested in a particular context then sold in another. A reflective surface only works if there is somewhere to reflect it to. "Graphite is a good electrical and thermal conductor".

I had completely misread that photo. I've now got it on a big screen without reflections. Forget what I've said and I will start again The crack is slightly concerning and may need repairing. So I suggest you ask an SE to advise. I think an over-plate of ply will do the trick but it needs to be seen in context and up close.

For other readers, it is indeed a real and a very bad possibility. I have been there when it happened. Our subcontractor didn't tape the joints properly. Our plumber had insisted on doing everything from insulation up. and it was the only time ever that we relinquished control of the slab concrete. It must have been 20 years ago and he insisted he was experienced and that it was fundamental that he had the package. I became wiser on that day, The pump-mix concrete got under the PIR which floated up to the surface. Suddenly I became the only person with a clue what to do, and I had them 1. stop pumping. 2. bring in concrete blocks, tread the pir down and lay the blocks on them. after about an hour the blocks came out and levelling continued. There will still be a skin of concrete under that pir, but it all turned out ok. In hindsight I think they taped the joints in the dpm but either not properly or the concrete was spouted at an overlap and forced it off. Plus there wasn't an edge detail (the edging under discussion here, did not then exist). it was potentially very horrible, and the need for sealed laps and careful pouring was demonstrated. Thus I will supervise and inspect. Maybe I will do the first room myself to test for any difficulties. Any recommendations for a good sticky tape?

you mean the yellow version? JG? Is it more robust? Define flat and level please? 3mm under a 3m straight edge with an overall tolerance of x? Your mate gets it right but a lot don't, from what I read.

Ok I'll maybe buy one and fix it and give it a prod test. You appear to have a pump mix concrete that is 200mm thick or so. We will have 45mm to whatever self-levelling screed. Is the yellow stuff stapled on?

Yes there is 35mm variation on the slab, with dips occurring at various areas. It is an existing agricultural slab which was good enough for tractors and barn use. There are a few local lumps too where the slab was extended or adapted but I'll have them chipped off. Overall though, now that the rain doesn't get in, you wouldn't notice the variation, except that the sole pate is all level, packed up from zero to 35mm. The insulating slabs will follow the shapes smoothly enough. Now that the rooms are formed we can use different thicknesses of eps on the bottom, and optimise the use of insulation rather than thick screed. But sods law combining with likelihood has it that the biggest room also has the maximum variation within it.

For context this shows the construction. So to the external face there will be a pir edging onto the block face. The finished floor is at the top of the block. Elsewhere the construction is all stud., and no facings yet. Obv we don't want to flood screed through the walls. Btw that is the offcut pile from several 100 metres of stud.

When fitting this stuff to walls, does it self support between studs or need some help? Otherwise fixing ply or other to the all room perimeters is a pain and a large cost for something that is working for a couple of hours. i'll get it as 100mm probably. the screed looks like being between generally 55mm ish, but from 45mm to 85mm due to some extreme wobbles in the floor. For most rooms I can vary the insulation thickness but the biggest room has the biggest variation.... of course. Or maybe we first pour some latex in the low points.... is that much cheaper than screed though? (screed seems to be £600/m3 or more.) Currrent logic is to have 100mm PIR on top of eps, which will be variously 100/125/150 according to the slab level. Thus the screed top level will be a set level but the thickness will vary at dips and humps. It's a right fiddle but worth about £4,000 to optimise screed and use eps instead of pir. That's a good few day's survey, research and analysis by my book.

That looks to have been exposed for a long time. Was the bit still there or long gone? It looks to have been a " shake" in the timber which was never contributing much strength. I see nail holes. Did you take something off? The house isn't about to fall down but ask an SE for assurance by all means. If you might be selling in the future then get a letter from the SE. If it had to be strengthened ig would be easy but ugly so you'd then box around it.

I forgot about compo and can't remember where that was. Is that short for something? Midlands?

Ground should be well below dpc. Ramps work., aided by aco locally, but then the water has to get away to a pond or soakaway. For the garage you can have a small hump.

I wasn't aware. can you point me towards this please? Presumably some government policy relaxation (to allow more building??) rather than a technical matter,

See if you can keep the wood structure completely dry . as @JohnMo , but also with clear space underneath (not boxed in) so that it can have draughts and dry Unless you use very special timber it will start to go mouldy and rot immediately, and a 10 year max life should be expected for the wooden surface.

More questions. How recently was this built? The plaster looks damp still, and perhaps the floor too. How thick do you think the celotex is? Is there a space between concrete on the ground, and the timber floor? Is there any heating in the room? For an immediate benefit, stuff the draughty hole with rags: it will be a good test before doing it permanently.

Accepted. I can see that bigger gaps would fill substantially as you say, and the microscopic ones are the least issue anyway. and it is filling from the inside so the weather shouldn't be any issue.

Do we know that this stuff will stay in place / not detetiorate as a permanent seal? I'm wondering if some/ most of the seals are just a few fibres, because as soon as they cover a hole, the draught ceases and no more fibres will adhere. What happens when there is air pressure in the other direction (out to in)?

There will be specialist local roofing merchants who will know what is the local preference.

And what was mortar called in your area? Frog up or frog down? Did they request... Mr Flanagaj, would you awfully mind making us another batch of your excellent mortar whenever it suits?

Great. And what about sourcing the sand to be suitable and all the same? That's a huge advantage having been there and done that. Were you instructed on accurate mixing? What else did you learn about tricks of the trade?

They will have regular gangs too, not just picking up whoever is available or cheap. They probably aren't working on mass production sites. I think you would best put a query up on your local social media.... brilliant brickie wanted.

it will be fitting the space exactly, including any lumps and bumps, eg mortar courses, so will require a hefty tug. it will then start to expand again as it has been released, so won't go back in.