ProDave

Show us the circuit. Or just experiment. Start with 100K, measure the voltage it pulls up to when open. If that is nowhere near what it is trying to pull up to, try a bit lower.

We are one of those with no heating upstairs. and being inland a bit in the Easy Highlands we know what cold winters are. Fair enough if your bedroom must be 21 you will need heating, but we don't. If you are to accurately calculate heat demand on a room by room basis you must allow for heat from downstairs coming up, so must calculate the U value of the ceiling / floor. And again if a 3 storey house. Intuition says your upstairs rooms will need a lot less heat than the lower floor rooms. I would stick with UFH throughout, and the fact you are more likely to have carpet upstairs does not matter as you will need less heat anyway.

Put some dimensions on that drawing or tell us how many square metres? You will do well indeed now to build for under £1000 per square metre. We did, but it was a slow build with a LOT of DIY work and it finished about 5 years ago. But as others have said, once you have foundations in, that would be an easy timber frame built on site which is entirely DIY possible if you have some basic skills and tools. Other DIY things, buy some kwikstage or similar scaffold and do it yourself. no scaffold rental and no time pressures to get it done and scaffold down.

I stayed on a campsite that had something similar. A very long shower tray. It had fixed glass all along the long edge and the narrow edge (in your case facing the loo) completely open. The tray was so long that nothing sprayed out beyond the end of the tray, and you had an 800mm wide entrance.

Hold the gland nut inside the box with gland pliers, and tighten the outside of the fitting with a big spanner. Must be done before fitting the cable into the fitting.

The gland nuts don't look tight. If you stick with those glands drill a hole through them both and put a nut and bolt through. What's the rating of the terminals supplied with the box? though not a lot of room. I would have used a larger box.

It could have been built as a proper warm roof design and would not need ventilation

If you are on clay with a high water table you MUST concrete it in. Don't let anyone say pea shingle is adequate. I have heard most discussion this sat they prop it upright with temporary wood, and don't forget to fill it as you pour so it does not float out.

Don't use a crowbar, get a pair of drain cover handles. e.g. https://www.screwfix.com/p/monument-tools-115mm-manhole-keys/14087

Buy a shorter car (i'll get my coat)

Definitely. Our past house had a pump out of necessity as the drainage field was higher than the treatment plant. The pump would last somewhere between 5 and 7 years before it burned out and needed replacing. I was SO glad when our present house was given permission to discharge to the burn, no pump, no drainage field.

I don't drive mine daily but it is my summer runabout when the truck is being a motorhome. It never goes out on salted winter roads.

Won't be doing that with my GT I care for it too much.

I regularly carried 4.8M planks and 4.5M ladders on the roof of my Subaru Forrester, just with the 2 standard roof bars. The geometry of the car dictates the front overhang (in front of the bar / rack) will be greater than the rear, to prevent an illegal overhang at the back of the vehicle. Anything heavy, place at one side of the rack not in the middle to avoid bending the bars. Small things like battens, strap them together at front and back to make them more rigid and more like one item. Sometimes with things like that I would also tie down the front to the front towing eye and the towbar at the rear. Now carrying a bundle of 6M long unistrut was entertaining and possibly not entirely legal.

Plenty of estates have covenants preventing you parking a van or caravan on the property. Whether they are enforced or not is another matter. but if the objective is to present to the world how green this development is, they really don't want people like me with a big diesel powered truck living there do they?

I would be dead against my own battery (whether house battery or car battery) being drained at will by others. If the communal solar farm and grid scale battery wants to do that then fine. This will be a useful test of whether this grand scheme is actually viable and works, and what it actually costs the residents for their electricity overall. The cynic in me says there will be a covenant saying no ICE cars allowed and you must have an EV to live there.

In daylight yes. But they still run at night.

Just back from 2 weeks away. In that time everything was turned off, except mvhr, Treatment plant air blower, Fridge freezer, a sky box to record some stuff while away, Music player (Raspbery pi) and ASHP controller on standby but turned off. That standby load consumed 4kWh per day which averages at 166W. Not bad I think. It shows that almost all of what is metered (that I complain seems high) is actually stuff doing something. P.S. the biggest energy saving we have made is my daughter chose to move out.

I commisioned mine to English regs that clearly state requirements for each room. Scottish BC never showed an interest in or asked for any documentation. I now run at a lower rate and it all works fine.

Post whatever drawings of the roof that you have, that they should be working from.

Yes but I still have some unresolved issues with the render so I cannot recommend it at the moment and certainly not if you intend using Baumit render.

Done 2 self builds and not a single objection to either.

MCB or RCD tripping. If RCD you need some test gear like an insulation tester.

Run joists end to end of the house, supported on sleeper walls aligning with each of the internal walls. Repeat for upstairs (so internal walls made structural) with stair hole. Your widest span will be the kitchen / diner, the joist supplier will size them for that span. I am surprised at the posi joist sizes you quoted. My longest span id 5M and my joists are 300mm deep. The narrow joists you quote won't leave much room for 110mm waste pipes for instance.

Looking again at your plans, is there any scope for getting access to your plot from Priory Lane? If you could then the SW bit of your garden currently where you drive to get into the plot, could be a nice bit of an evening sun trap garden. Is the "existing outbuilding" in the top left by any chance a single garage? If so it will have vehicle access rights to Priory lane. That certainly looks like a driveway entrance in front of it.