Mr Punter

A decent groundworker / machine operator will do this 4 times faster than you with no major cockups. It won't cost that much. Don't do it yourself. It will cost you a lot in machine hire, extra concrete, sleepless nights etc. I like the house. Are you actually wanting to use white mortar in the brickwork? It could work if you have a local supplier of white sand but otherwise very hard to achieve.

Possibly it detached during cleaning. You will never know. Bad news getting significant soot after such a short time. Do you have another source of heating that is less polluting?

You may want to avoid having the rad pipes heating the screed. They run much hotter than UFH and you will get hotspots in the floor. In the middle of the insulation layer would be my favourite but I don't know what depth you have.

Stuck down LVT is very hard-wearing and the finishes and patterns can look excellent. A rug or two can break it up and add some softness.

I have done a few floating floors with 22mm T&G chipboard over insulation and have not had any issues with bounce. It weights about 16Kg per m2, so a 4m square room will be a quarter of a tonne. It needs to be installed correctly - left in the room to acclimatise, 10mm expansion gap all round. If you have tiles you could use a fibre cement type instead of chipboard.

Connect a new stub stack with an external air admittance valve via a branch. Clip stack to wall. Shopping list: https://www.toolstation.com/mcalpine-vp100e-push-fit-air-admittance-valve/p25541 https://www.toolstation.com/branch-110mm-9250/p31580 https://www.toolstation.com/soil-pipe-110mm-3m/p68433 2 x https://www.toolstation.com/soil-pipe-clip/p80712

Their Google reviews are shocking, but I guess they must be cheap. Persimmon are among their customers. I might give them a try.

What a beast!

You can go to 1:150 with a 150mm pipe. It needs to be spot on - not just chucked in by a gibbon. Whose land is the 90m dig? Is it verge or road? Given the option mains gravity drainage is a clear winner.

Or just clad the front in downpipes in a herringbone pattern.

I have never had an SDS that doesn't have a clutch. I doubt you could even buy one as I would think the seller would risk being sued.

If you have already designed this not to have UFH you will need oversized radiators and pipework. For the DHW you could just use an electric immersion if you need to give the tank a top-up. If you put some PV on the roof you can dump this into the tank as well.

I know it is not to your liking but I think a single continuous run, with a single downpipe on the left, fixed to the dark cladding instead of the render would look cleanest.

With basic fuel prices so high, the saving on red diesel is negligible. I doubt it will add more than £10 to the build cost of an average house.

I have done lots of cored holes in concrete blocks with a Makita and a Dewalt SDS drill. I did do plenty of wrist strengthening exercises over the years and these must have paid off... Easy 2 per block. 3 would be fine, but not more than half the block removed horizontally over, say, 3 blocks.

Just to add to this, the fees I have paid for in the past for planning plus building regs have come to between 2 and 3 percent of project cost. Projects have ranged between £200k and £3M. We agree fixed fees.

They need to base their fees on something, and % of estimated build cost is a simple one. If you think it is too much, negotiate, explain it is over your budget and ask if they will do it for less. If the design is simple you could get an architectural technician to do it.

If it is brick and block the doors often sit mostly on the outer leaf. I don't have the inner leaf built at thresholds - just 25mm perimeter insulation and have the floor slab and screed run up to that, so there is only a 25mm cavity at that point.

Windows and external doors can take an age. I once got delayed on some Hardie cladding pre-covid. It held up the job for 3 months. Waiting for contractors can be annoying. I often find gas connections hard to sequence and it can end up going in last, which delays landscaping and paving. 12 months if you are using a main contractor.

I have heard of it but never seen it in merchants or on site. I think it is a specialist product.

I would want that stripped and done correctly. And battens to BS 5534. Ask Building Control or your warranty provider to inspect and break the news if you don't fancy it.

I have only had LVT onto chipboard sub floor with no underlay. If they are not paint grade blocks they can be a pain to get the paint to cover.

The external walls look nice and thick. The bifolds opening into the kitchen cause an obstruction. Sliders are easier to open and the lift and slide type are very good for airtightness, where bifolds are not. The TV will be much too far to view from the kitchen. The island looks a bit odd. I can't work out what the extra 600mm worktop behind the hob is for and to get to the units by the overhang you would need to move the chairs / stools. There is a lot of glazing and the room could easily overheat in the mornings. Make sure this is properly modelled and mitigated.

LVT is only about 3mm thick. Just paint on the plant room walls.

There is another thread on here where someone has had some steelwork installed that may not be to spec and other instances where there are existing structures to be assessed. For a loft they will need to know the timber sizes, roof structure and supporting walls and unless you have an architect to supply this information to the SE you may want a site visit.