Mr Punter

You can have it tested quite cheaply. Worth doing.

I agree that GRP is probably best. I don't think the valley tiles will sit right with the 2 different pitches. With no experience of pitching a roof you are attempting something a bit tricky. The valley rafter looks a bit sad but once the other rafters and valley boards are in it should be OK.

Deffo damp. What was on the spec for remedial damp proofing/ tanking / waterproofing?

This looks like different bricks were used when they go 7 courses from the top of the door. Different mortar mix too. Did you by off plan or was the house complete when you saw it?

The site bricklayers we have had can be fairly rough, but they have a service person that acid treats and jetwashes the job and fills in missing mortar pointing.

@Bitpipe who did your structural warranty? I have found that lots of providers do not like waterproof concrete alone and go on to ask for drained cavity, which sort of defeats the object.

If you are keen to increase the bearing you could use some metal shims or some runny structural grout.

Not a self build? Are you VAT registered? I am about to start 3 new build flats to rent. We have a company that owns the land and will own the future flats and they will get our development company owned by us who are VAT and CIS registered to design and build for a contract. Dev company can reclaim VAT and does not need to charge it on as it is new build. I suggest you get your own advice as a mistake could be expensive.

Did you get a quote to connect to the sewer? I would be very surprised if it runs to thousands.

Stick with what you have. Internal doors 2400h look impressive if they are a decent width. Door blanks are cheap and good quality.

OP needs whole house cover. The mist systems are good for small areas / kitchens in student HMOs but cost prohibitive for whole house.

It is advisory, not mandatory. They mainly check that the sprinkler heads have not been sealed with paint and mastic and they do a flow test at the intake. If you have a pumped systems it is probably worth doing but not for a main pressure system in a private dwelling.

Cost is about £2,500-£3,000 for 4 bed house. They don't activate by accident. They are fit and forget. There is an isolator normally near the entrance, so they can be switched off after the fire is safely extinguished. Because they activate quickly and only close to the fire it can be brought under control very quickly. If you have to wait 20 minutes for the fire brigade you may have to say goodbye to the house.

Why do you think this will be the case?

Deffo forget the Saniflo. I would rather crap in a bucket and leave it in the middle of the bedroom. If your proposed WC is near an outside wall and the drain is in the vicinity is is well worth taking a 110mm pipe out to a new stack pipe connecting into the (combined?) below ground drainage system.

Make sure fascia / soffits / gutter does not overhang.

Nice. The utility is huge as is the office. With 4 bedrooms, 2 ensuites and a bathroom can be good. Will you have a rooflight over the corridor? I like the doors onto the covered area / verandah. Have you considered privacy and overheating?

CAT 5 or 6 but this can be run in voids, boxings, cupboards, loft etc and the Ubiquiti stuff is excellent seamless wifi. Otherwise, go for the powerline stuff, which is cheap, easy to set up and fast.

Boosters are a bit crappy and tend to throttle the signal. Cat 5 or 6 cable from the hub to near where your signal is weak. I have 2 x ubiquti unifi ac lites serving a 4 storey + roof terrace and get seamless wifi everywhere.

So has that ridge tile you showed in the pictures with the big gaps been sorted?

Regarding point (1) yes get this properly engineered and approved before you start. Point (2) Thames water should allow you to discharge into the sewer, (if you cannot do soakaway, watercourse or surface water sewer) albeit you need to mitigate as far as possible. I have done this in the past. I can't help with (3) and I doubt I ever could. I have just gained PP for a site and will hopefully start in about 2 months but chalky site on mains drainage and I can get TBS electric albeit at stupid expense.

You don't need the DPM.

Anyone fancy calculating the maximum viable board thickness? Or do you have better things to do? Insulation board is normally metric 1200 x 2400.

The membrane is only there to stop concrete escaping between the board joints bridging the insulation. A few holes will make no difference. You could just tape all the joins.

Looking at the BBA cert it may be best to clip the mesh to the insulation through the vapour barrier and have the mesh above centrally.