Mr Punter

If you have a decent job I would not advise that you give it up or reduce your hours. Better to improve your position and gain promotion / increase income. I assume you have looked at what you can get for an extra £250k? Have you done numbers on whether the work will increase the house value by at least what you are spending? I don't know why the architect needs to be involved throughout and paying a percentage may be wasting your money. Maybe post the plans and invite comments. There may be areas where you can save lots of money and it will make little difference to the end product. WRT planning consent unless you make changes to the externals it is unlikely that you will need to go back to them and it certainly would not be 18 months.

I think the gutter needs to be finished in GRP or similar and needs a min fall of 1:200 to the outlets. Make the outlets are lower than you think they should be as there is often a build up of material near them so the water does not drain. Design it so if you block the outlets the gutter will surcharge down the outside of the building.

Screw in from both sides alternate 50mm from top and bottom. 200mm ctrs should work fine so 10 screws per metre. More won't hurt. Screws not fully threaded are better as they pull the pieces together.

The search is correct. OK subject to ground conditions. No good on clay. My brother had an orangery add-on with a raft. The rest of the house was piled 25m. Clay soil. None of the 3 pairs of doors now open properly and he will probably have to demolish it if he want to sell the house.

Quite a small room! You can do the brickwork tomorrow but leave a day before the plate on the sleeper wall. When you do the wall plates you may find it easier to nail the hangers on first. The joists do not need to go right to the walls, you can leave 100mm and pack those gaps with insulation / foam.

In timber frame it is the horizontal timber - head binders, sole plates, joists, rim beams - where the shrinkage happens. I think these still exist in SIPs.

Yes, move it inward by 100-150mm. You will also need to allow for differential movement between the frame and the blockwork, especially at upper floor level, as the frame will shrink downwards and the blockwork will not.

But this does not have what @Triassic needs which is spec and detailing for fire barriers in ventilated rainscreen cladding

You should close the cavity (usually with 2 x 2) around windows and doors. This stops a fire in the house breaking through into the cavity. You could fix intumescent barriers at the top which would choke down the chimney effect in the event of a fire. They don't seem particularly easy to find or specify though.

Trouble is, if he closes the cavity the ventilated rainscreen cladding will not work as designed and he may get damp issues. The cladding manufacturer will show continuous ventilation top and bottom.

We had a 30s house with that style of door.

They are not had to get hold of. I have one I don't need. With three prongs. The security fittings I had were made of a different metal and tended to fuse to the bolts. I am in Sussex.

These are really good at stopping small children opening the door.

Never too late for you to dig it up!

CAT5e

I can never work out why UFH pipe runs always have a very congested hot 'corridor'. In your second pic there seems to be 7 pipes in 600mm. It looks possible to alter the design quite easily but maybe nobody can be bothered.

More like a continent than an island! Once the cabinets are all level and screwed to each other they will be fine.

I would concrete it. We once fitted a plastic tank in clay in dry conditions. Concrete base and just backfilled with shingle. The following year after it had rained a lot the sides and base were misshapen. The tank was plenty oversized so we filled the bottom of the tank with concrete to prevent if from collapsing but I would concrete all round if I had my time again.

Bear in mind if you have 2.7m downstairs you will need a couple of extra treads on the staircase.

You could have a bank of 300mm on the left hand side and I don't think you would need any on the right. Allow 1000mm width for the hedge and plant it 400mm back from the edge of the pavement, then slope the bank at 45 degrees. Grade the rest away from the house. You will want a fall on the patio of 1:50.

If you buy a "no mar" tip for your Paslode 1st fix nailer and make sure you carefully adjust the embedment depth, you should be OK, but hand nailing is safest.

Maybe just the camera angle but it looks like there is a fair amount of space between the house and the heras and the ground looks fairly flat. Could you not grade the garden slightly towards the path, then have a small bank where the hedge is?

A suspended timber ground floor needs decent subfloor ventilation to outside air and you need to make sure the sub floor area is well sealed from the room above. The Celotex suggested is ideal for this, with a generous application of expanding foam in the gaps to help it fit really tight. You could screw or nail some pieces of batten at 600mm ctrs to the joists at the bottom to support the insulation level with the joist tops and it would also help resist twisting. I would go with 22mm Egger Protect T & G boards (if they are reasonably available) glued and screwed. Seal the edges to the walls with mastic. Overlay with VCL (if you really want to) then ply screwed at 200 ctrs then heat mat and tile. Work out the buildup height carefully so you don't have a step into the adjacent areas.

Bloody hell that was quick! I was about to suggest a new concrete floor, but since you have started, just carry on with what @Russell griffiths suggests. Run some DPC behind the wall timbers before you fix them - easiest to staple it to the back to hold it in place.

The Guttercrest stuff seems to work out about £30-£50 per lin m including downpipes, depending on complexity and sizing. I don't imagine the seamless stuff would be cheap as they must need special kit in the lorry - a bit like some of the metal roof stuff. It is probably only used for commercial jobs where they have nice long runs. I wonder how they form outlets, stop ends and corners (where most leaks seems to happen) without seams, or does the "seamless" bit only apply to straight runs?