Mike

So what, you can’t sue them. They owe no duty of care to the OP. You can't sue them, but they can make your life miserable if they have good reason to doubt your adequate compliance with the Regs. Require you to open up the work, take samples, withhold your completion certificate, line you up for an enforcement notice or a fine...

On top of your insulation, DPM & concrete slab, the main options are: underlay, then 22mm moisture resistant t&g chipboard, then carpet/lino/vinyl/cork or similar underlay, then t&g engineered flooring battens plugged and screwed to concrete, then t&g solid wood floor. Yes, this would introduce an air gap under the timber. screed, then ceramic tiles/stone/carpet/lino/vinyl/cork The underlay can be a (soft) proprietary product, or something like 25mm polystyrene. BTW, you need the concrete (and any screed) to dry out thoroughly before laying anything over it. With a floor insulated below the slab to current Building Regs standards, I'd not use a VCL (the temperature below the timber surface is unlikely to lead to condensation), unless the manufacturer requires it for warrantee purposes.

With luck, at least some of it would be divided into lots so that small builders & self-builders can do some of the building. See also Investigation into suspected anti-competitive conduct by housebuilders: https://www.gov.uk/cma-cases/investigation-into-suspected-anti-competitive-conduct-by-housebuilders Although I don't think that housebuilders are the (main) target. More likely it's about buying up (mainly) agricultural / 'grey belt' land to build New Towns and the like. That's not far off what happened to acquire the land for the post-war New Towns (see the New Towns Act 1946), except the land owners then were only paid the agricultural value.

It is. I just wouldn't do it if you choose solid timber, instead of chipboard or engineered timber.

Yes, if you're using engineered timber boards or chipboard (the latter I guess, as you say '22mm moisture resistant'). Just make sure the DPM's not damaged. That shouldn't be a problem if you lay it on an underlay, allow adequate expansion gaps at the edges, etc. For solid timber boards, which seem these days to get glued to the concrete, that could be a problem at the edges if the boards lift & take the DMP with it. I'd probably plug & screw battens to the floor and fix the boards to the battens.

An 8m glulam beam should be no problem, but you will need a structural engineer, mainly to verify any upgrade to the walls that are carrying it - for example you may need a wall / piers that are wider that the 'standard' 100mm. I've done it myself with a 6m clear span onto 140mm blockwork.

Yes, it's only the exhaust that's concerned. As long as the duct is adequately supported to at least the manufacturer's specified intervals, and well insulated, you're fine.

Yes, that that's a key consideration. Build to suit the neighbourhood and don't over-develop / under-develop the site - or if you do, be aware that that's what you're doing and what the consequences may be. In principle, but the floor between it and the rest of the house above will need to be thermally insulated to Building Regs standards as it it were to permanently stay that way, without heating, with ventilation, the same as any other unheated under-floor void. Though you could still insulate it, read for future conversion. Since it would have been signed off that way, you'd need a new Building Regs application to incorporate it into the house at a later date. Or you could go half way - build as part of the house, but not divide it up into rooms and install the minimum of services, so it can be used as a games room / gym.

Below the DPC they need sealing against moisture as above. Above the DPC it's airtightness that you need to seal against. If it's being plastered you only need to seal the junctions with windows, doors, ceiling etc. If plasterboard (or just painted brick/blockwork) then you need a 'parge coat' too. There are already other threads on these topics.

Some builders can't get it right even when there are drawings, unfortunately.

More-or-less If your polythene DMP will be below the concrete slab, then after pouring the concrete, trim the polythene off a few mm above the slab. Then paint the Aquaseal over the slab-polythene-wall junction (so it will also overlap the top of the slab by at least 100mm) and allow it to trickle down into the junction to fill any small gaps, then paint it up the wall and over the existing DPM. Before the final coat fully dries (it will be tacky), throw some dry sharp sand onto it to provide a key for the plaster / next layer. Check the manufacturer's instructions for the primer and number of coats & their thickness (m²/litre). And do discuss it with Building Control to make sure that they're happy in your particular case.

As above - https://forum.buildhub.org.uk/topic/33449-dpc-not-lapped-as-specified-by-architect/#elComment_492131

You need to string a line along across the top of them and trim them all to the same length. You're right that it mustn't collect water, but it's normal to use a timber 'tilting fillet' to support the lower edge of the last row of tiles at the correct height; the membrane goes over the top of that. You may want to add a 'underlay support tray' as well, for belt-and-braces. Doing it this way means that the tiles do not rest on the fascia board, which can then be easily installed / repaired / replaced without disturbing the tiles. If you're using an over-fascia ventilator, then follow the manufacturer's installation requirements / BBA certificate. As above, it will normally be easy to add the fascia board later, unless you're using a vent that doesn't permit that - in which case I'd personally choose a different vent.

Yes, somewhat tricky if you have no access to the data...

Aren't the wall ties pulling the insulation back against the internal leaf? Or can you add more so that they do? If so, and if the insulation board has an interlocking profile and is intended for full fill, then I'd not worry too much, though it's far from ideal. Otherwise, I'd consider foaming the top of the gap using Illbruck FM330 applied with a foam gun - very gently, so that the foam doesn't push the insulation further out of place. It may help to use some blocks to restrain the boards temporarily while the foam hardens. That will more-or-less seal off the lower part of the wall and limit the convection between wall and insulation to below that level. Consider adding additional wall ties if necessary for the rest of the wall - it's most important they they are snug against the inner leaf. At least you have render externally, which is a useful shield against problems of rain penetration.

It's only the exhaust duct that you need to worry about. If that drains back towards the MVHR unit, as recommended, then any condensation will exit via the condensation pipe build into the unit. It's also acceptable to have a high point in the duct, so that part drains back to the unit, the rest to the outside. Maybe you can do that - i.e. take the vertical pipe slightly above the exhaust grille, and then angle it slightly down from there.

It takes moisture vapour hours to travel through the thickness of plasterboard*, so daily variations are immaterial. It's the flow over the course of weeks that's important, and that's where real-world data would be very helpful. *e.g. Mortensen, L. H., Rode, C, & Peuhkuri, R. H. (2005). Full scale tests of moisture buffer capacity of wall materials. In G. Johannesson (Ed.), Proceedings ofthe 7th Symposium on Building Physics in the Nordic Countries (Voi. Volume 2, pp. 662-669). The Icelandic Building Research Institute, IBRI. https://findit.dtu.dk/en/catalog/537f0d1c7401dbcc12009157 Easy enough to concatenate files with the command prompt: I'm sure that I can manipulate data provided in any format, by the minute, day or whatever, as long I know what it all represents.

That would be really useful - thanks for remembering this thread!

Not sure, but that may have changed on 1st January 2023, when RE2020 (the current thermal performance requirements) started to apply to buildings under 50m². AFAIK the exemption only applied to RE2012. https://www.inc-conso.fr/content/1er-janvier-2022-entree-en-vigueur-de-la-nouvelle-reglementation-construction-re-2020-pour

My lastest one is a Kaiweets KT360. Looks like a Chinese knock-off DeWalt, but works well. That battery lasts for ages, but still worth getting a spare.

Damp normally evaporates from a wall within 2 or 3 brick courses above the outside ground level. It doesn't 'rise' unless there's impervious render or the like preventing the evaporation. Could be penetrating damp, could be condensation. Photos inside and out may help, if that doesn't answer the question. Chemical DPCs are normally not needed.

Not quite as well, but current thinking is that it's unlikely to make a significant difference. The last paper that I read on the topic is this one: https://www.passivhaustrust.org.uk/guidance_detail.php?gId=55

You may need a certificate before 'occupation', but doubt that storing things counts. You'd have to see if there is any case law. https://www.legislation.gov.uk/uksi/2010/2214/regulation/17A#extent-E

It may be damp, I'm not convinced that it's dry rot. The first image looks more like heavy efflorescence (if so, it should crush to a powder and will dissolve in vinegar), and the timber in the 5th doesn't have the typical cracking that dry rot exhibits. Even if it is, the key is to identify where the damp originated, prevent it returning, dry everything out and replace all damaged timber. In addition to fixing the rendering and guttering (and the roof?), you also need proper ventilation. For example, those PVC windows need automatic trickle vents (I'd guess all other rooms do too), unless you install MVHR or similar. And since you've hacked off the plaster / need to fix the render, it's an ideal time to look at wall insulation & airtightness. Finally, beware that the 'Artex' textured ceiling may contain asbestos. Tests are available and there are other threads on the topic.

Forget our viewpoints, ask the scientists. https://www.metoffice.gov.uk/weather/climate