Mr Punter

I understand that different LAs take different stances on this, where some are willing to accept a completed shell, others completed foundations and some may even ask for it to be completed and occupied for a period of time. I suggest that @JamesHopeful has a chat to the LA explaining what he wants to achieve and see what they suggest. There is no point in imagining that they will not enforce as this seems to be one area that is not so subject to budget restrictions.

Normally the PD rights that are removed only cover extension and enlargement. Solar panels, rooflights, windows etc are normally still OK to add.

Sounds like overkill. I have only used these on the floor and we laid them in tile adhesive. Adhesive plus screws may be best, but 150 centres is intense. Not so bad if you are fixing down onto a timber sub floor but too much for a wall.

Hi Josh As others have suggested, the glazing will probably lead to overheating. There are solutions such as SageGlass, brise soleil and external shutters but they are expensive and best considered early on. The plans look like traditional blockwork walls, so you might want to look at fully filled rigid insulation or if you increase the cavity, polystyrene beads. Traditional render and set internally is best for airtightness. I don't think the cars will fit the garage. Maybe 2 doors or one much wider? A lovely big house.

Maybe you could just have 8 around the edge and 2 in the middle.

With those washers I would just drill a 6mm hole through the board for red plugs and 50mm x 4mm stainless screw and plug through the board. They give you 100 washers, so 10 per board. 1 in each corner and the other 6 spaced around the edges. You could squirt a bit of ct1 in the holes if you want.

It is not going to happen as the first floor walls are built off it.

If the soil conditions are suitable I would look at building the whole thing on stilts using screw piles as suggested by @JSHarris.

If you are able to rule out UFH and tiles, you could get some insulation on top of the floor, then finish it with an overlay board and LVT (Amtico, Karndean etc) and heat with radiators. If you can live with the floor being 60mm higher, you could use 40mm thick pir type insulation (Kingspan, Celotex, Xtratherm etc) at a cost of about £7/m2, but the insulation improvement will be OK but not great. The fitting, overlay boards and finishes will likely bring the cost up to £70/m2. If you are feeling flush, you could use Kingspan Optim-R 40mm thick which will be four times better at insulating but will cost an extra £130/m2 or so.

Sometimes they use a tool to create a slot in the screed while it is still green

I think the issue that makes this difficult to rectify is that the first floor walls will be built up off the offending 18mm chipboard, which is probably glued to the floor joists, so the chipboard cannot come up without taking out the roof and walls. Overboarding is the only option. I am keen on 22mm Egger Protect, glued all edges and to the 18mm and screwed. Perhaps get them to compensate for the required door adjustments.

Any structural engineer experienced in steel framed buildings would be able to design this for you. You could contact a firm who do agricultural buildings and see if they could recommend someone.

It looks like one of your runs starts outside your plot boundary. Also you may need to be careful with scaffold and eaves overhang with the neighbours. Roof area looks about 50m2

You cannot use the combination of rise and going. 2r+g must be between 550 and 700 Reduce the rise and add another tread or two. 2400 for first floor ceilings is a bit mean.

Basements are fairly high risk and you need to consider ground conditions, safe excavation, ventilation, daylighting, retaining walls and waterproofing. Given the FRA I am not sure why you would bother. You would need a minor material amendment application for this. You could only use the basement for non-habitable purposes - cinema, gym , store etc.

You can get a tray like that which is only 30mm deep and sit it on the concrete. You just need to box out the bit for the waste. You not notice the 30mm step. Get one that is slip resistant and easy clean.

For timber , concrete and steel beams or joists on a residential project, 4m spans are fairly economical. Much more and it is worth looking at additional midway support.

The joins need to be filled to achieve the fire rating.

That is a very good price. What was and was not included?

I think you could get it for £22.5k but you may have to mess about with just using their approved installer. Yours are coming out at about £1,000 per m2 and you should be able to get similar for £700. You u values look a bit crap too. Get a proper window schedule done and use this to shop around. You don't need to get all from one supplier, so you could have doors from one and windows from another. Have you tried IdealCombi?

I think you will need an engineer to check the design. They may be able to advise where you can economise with materials. Will your welder do all the required fabrication? Here is one we had made and it used a central rectangular section. You could do similar and use 2 sections spaced apart a bit which would help stop any twist.

They are a real pain to deal with in my experience. They keep on phoning you.

A very interesting idea @edsr Regarding how this is structured, have you formed a ltd co with shares for each potential self builder? Already allocated plots? Worked out SDLT etc? What if you don't gain pp or shareholders want out or die?

Nobody dies from that

Tape the edge to the celotex, as well as taping the laps.