Mr Punter

I can't work out how you got such a good score (83) with such poor insulation. Do you have solar panels?

If you are outside a Conservation Area and there is no TPO or planning condition you can do what you like.

LABC foundation depth calculator:

I am not sure that the foundation is deep enough. 2.4m may be more like it. The low density polystyrene is heave protection and used on the inside of the foundation trench. It can be difficult to use as it tends to float in the new concrete.

No, the housebashers often have "Type Approval" style certification. Mostly the only things that get looked at are the paperwork. Site agents are more interested in RAMS from their subbies than build quality.

If the tiles are the right type you can lay them onto adjustable pedestals.

Stupid pop-up sockets?

What do you mean by this? If you have planning drawings that you are happy with they should be able to use those. You may need some input from a Structural Engineer for some aspects. If you want changes to the approved drawings you could get an architectural technologist to do these. If they are simple you can just mark up the existing drawings for your chosen timber frame company.

They should all be able price from planning drawings, without a fee. You will need to chose the spec you want.

Unless you are using a heat pump, the hot water will cost the same to heat for 1-3 but you will get some heat losses from storing hot water in 1 and 2. Maybe a cold water accumulator, decent electric showers and under sink water heaters for each flat, plus individual air to air heat pumps would be best.

I can't think how the website has any bearing on how good they are as builders. Some of the best builders I know are semi-literate.

If it was not compulsory very few developers and builders would bother at all with airtightness.

The house will need to achieve or the airtightness that was used in the as designed SAP, which must be less than 8.0m³/(h·m²) @ 50Pa. With leakage rates this high you would need to add huge amounts of insulation, PV, etc. to compensate. Typically the design will based on the notional dwelling and will be less than 5.0m³/(h·m²) @ 50 Pa.

Can you do the first bit in waterproof concrete?

With the resin, get the top fixing in and done up for each bracket, then through drill for the bottom fixings so you know they will be in the right place. Stud size = hole size minus 2mm.

Skips will be easiest, otherwise you will need to pile it up and get a grab lorry.

I don't think the hollow sound would be an issue but it may not work well if the tiles meet in the void. Neat chasing!

You could use the insulated metal sandwich panels. I have some on a garage and there is no condensation.

Where were the slats from? They look like 2 x 1 treated with rounded corners. I am looking for something like this.

Looks a very neat job. It takes a bit more work to do the capping, cut the pales to the slope and shape the end few around the wall but it looks good.

Yes on problem walls Weber suggest Rend Aid as a 1st coat. It has lots of cement and is sticky as a sticky thing. The mesh is also good minimising cracks.

You can get Weber OCR in bags at Wickes.

Sounds like a bargain. Yes, also a bargain. The copy batteries can be better than the originals. Old gas and cold weather can cause misfiring. Obviously please make sure the tools are not nicked as this just encourages thieving.

It is fairly subjective. The overshadowing would need to be considered harmful to the amenity space in the garden. In the past we have submitted shadow diagrams at certain times of day and year. You may need to get a daylighting specialist to do this but it may be that unless your neighbour brings it up the planners will not bother.

I don't think you would need to tape and lap any breather membrane. It is only there to support the insulation. Any VCL (probably not required) could go on top of the floorboards.