Mike

There's certainly been international cooperation for decades, and current UK & European regs are based on CENELEC HD 60364 (itself a variation of IEC 60364) with local deviations. Ring mains, twin-and-earth cable, fused spurs, on-wall cooker switches and metal consumer units are probably the UK's main peculiarities. I've only studied the UK & French regs (informally, not as a qualification) but yes, modern French CUs are certainly much bigger. That's partly due to the use of radials everywhere, but also because the French rules just require everything to be split into more circuits. I'm not sure if that's a French peculiarity, or common across Europe. For example, a UK 20A radial circuit can serve 50m²; in France it can serve just 12 sockets (doubles count as 2), or 6 sockets if serving a kitchen worktop. Plus separate circuits for each dishwasher, washing machine, freezer, etc. Consequently, excluding lighting, my living room has 3 radials and my kitchen has 8 (though I could have got away with 6). By the time I've added lighting, the other rooms, MVHR, water heating, a couple of Shellys, Willis heaters, a load-shedder, and a lightning protector, this is the CU that I'm installing (and that's just the first part): In addition, I have several dimmers & LED drivers to accommodate, but I can't add them all to the CU without exceeding the mandatory 20% unused capacity, so they'll be going in a separate 2-row cabinet. Then, since it's an apartment, there's another 2-row cabinet for the smart meter and the main RCD / isolator. And there's more - a separate communications cabinet for TV, telephone & internet cabling, with another for a broadband router / TV box. My 'electrical technical space' will therefore extend from floor to ceiling with 5 separate cabinets plus an access hatch:

As a brief update to my initial post, with the information provided here - thanks again - and some data donated from elsewhere, I did come up with a 'best-guess' internal climate to use in WUFI. The results suggested that biggest risk of moisture build-up was caused by adding any sort of VCL, so there isn't one - but that's with MVHR, in a French climate, and with low external moisture penetration. I did rig up some sensors before fitting the insulation and will be monitoring the internal environment too, so hope to have some real data to share at some point. That will take at least 18 months though, as neither the sensors nor the MVHR are switched on yet, apart from to run spot-checks.

My wall insulation is a just short of 3m high too, and the maximum length similar to yours too and there's no problem. Just cut the batts a little longer & wider than needed, with the stud about 90 to 95mm off the wall for a 100mm batt (experiment - you want a good friction fit without over-compressing), and they won't be going anywhere :)

I believe that was the origin, and indeed they're not found in Europe. They no doubt regarded as a potentially dangerous British curiosity here in France. Potentially dangerous because, if the ring becomes broken, you could with 32A passing through cables that are too skinny.

They don't have to be; they can be fitted behind the studs the same as the rigid, as per my photo above.

Better still, tell him what level of airtightness you need! There are several threads on here explaining what it's important. If your contractor is already signed up, then you'll no doubt need to do some explanation & negotiation. <1.0 ACH is certainly achievable; targeting the PassivHaus standard of 0.6 maximum would be good. However it''s way better than the average contractor, so they won't get there without added some extra effort, a little extra expenditure (really not that much) and understanding of the techniques and materials. However, don't rely on them to get it right; you'd need to learn about it too, to avoid the potential problems.

I experimented with WUFI intensively while I had temporary access to it, but I don't have a license so can't help directly. However, it's important to know that WUFI's results are highly dependent on the internal environment (temperature and humidity) used in the modelling. Getting that right isn't easy (unless other software is used to create a model the building's environment first) as there's a lack of published information on the topic. In short, it may not be a quick or cheap job to get realistic results, especially if you're planning to 'modify' the internal environment with MVHR. Some of the issues discussed here:

I'd choose flexible / semi flexible with a friction fit - it's easy to fit free from gaps - unless you have a particular reason for choosing rigid. Not sure what the rest of your insulation plans are, but there are other advantages to natural insulation that may be useful. For example much improved decrement delay to reduce summer heat build-up (useful at ceiling level & in timber frame), good fire behaviour (it will burn, slowly, but won't drip burning plastic or release toxic gas), pleasant to use, negative embodied carbon...

I wouldn't describe that as welding. It's also unacceptable.

I've rediscovered a potential solution to the sash window issue buried in my filing system, available in Germany (Google Translation https://translate.google.co.uk/translate?hl=en&sl=de&u=https://www.adrik.de/fenster/WIN-Hochschiebefenster/Holz-TypS.html) and Denmark (https://www.vrogum.dk/en/wooden-windows-doors/vrogum-solborg). The second of these is most interesting as they have at least one UK reseller : https://enlightenedwindows.co.uk/products/german-wooden-windows/vrogum-solborg-sliding-sash-window/

@Annker - just a follow up to consider how you'll be cutting the insulation. If you're cutting lots then you'll want a power saw, which you may be able to pick up on eBay or hire. For hemp that has to be an alligator saw fitted with wavy-edge insulation blades*; for wood fibre a circular saw may be OK if it cuts deep enough, but check the insulation manufacturer's advice. *For example: The UK version of the Bosch Professional GFZ 16-35 AC + TF350WM blades (used personally) Festool 577231 18V (have seen it used) Dewalt + DT2979-QZ blade (unverified, but the blade looks promising)

+1. Most of those pictures are seriously alarming. +1

Yes, I'm surprised that that was their suggestion too. As you'll know, having read the thread, I was happy to pay the extra for hemp insulation, but I'd have chosen wood fibre if it hadn't been readily available.

Must have skipped that bit. I used the European equivalent on my mansard, but here there are several types of nylon brackets available to cut heat transfer; I've not come across them in the UK. Yes, that's the recommended method and reason :)

It almost certainly does, theoretically, if it has been used by the occupants of the house over an extended period, irrespective of what the residents / owner of the lane may say. Ideally your solicitors would have obtained an affidavit to that effect from the previous owners during the purchase process, if access isn't mentioned in the title deeds. Without that, continuity & length of access is harder to prove.

It's more-or-less the same system that I described in my various posts above. Though with thinner insulation (that could be fitted a little tighter in places) and, as you mention, without parging the wall first (disappointing but not unusual) and with the addition of a VCL that may / may not not be advisable. On the walls these are unlikely to be needed if the manufacturer's sizings are followed. On the ceiling they're needed.

Maybe it's just me, but I'm not clear on the problem you're trying to solve / how & why your idea might improve the situation?

It's not normally done because using the wall as formwork is cheaper. But, subject to some conditions (you're not involuntarily paying extra, the formwork is adequate; the edges of any hardcore are retained in place after the formwork is removed), it's possible.

Absolutely. Any door can open outward - front, rear, side, whatever.

A good idea :) The best price I found was €85, carbon filter included, from https://www.econology.fr/zehnder-comfosystems-caisson-filtrant-isobox-dn-160-filtre-a-pollen.html, but there's not going to be as much competition in the UK market.

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If you're willing to forego the DIY & the 90° bend, you may be able to buy them. The Zehnder IsoBox, for example, is made from EPP, has a DN160 connection & can take a pre-filter, a carbon filter, or both. Or a DIY filter, I guess. Paul used to sell them in the UK. I guess that other manufactures may make similar for larger ducts.

My main suggestion would be to change the bathroom to avoid having the bath, shower or WC against the Bedroom2 partition - or to make it a double partition - to reduce noise transmission. I'd chose to have them both against the wall, leaving the island free.

If you have a screed on top, it's likely that that you have a beam and block floor. AFAIK, there isn't an approved method for insulating below them, not least because ventilation below is required to remove the risk of long-term rusting of the reinforcement. For any insulation you'd also need to be sure that you were in an area that was Radon-free and flood-free, then work out how to get the insulation tight against the underside of the floor throughout. would likely be your best option.

I have an HP Zbook, but there are quite a few on the market. USB-C power delivery becomes mandatory for all laptops sold in the EU from 28 April next year, so it may soon be difficult to buy any other type.