Conor

You could have taken a load of photos and used augmented reality app! So obvious....

My comment was a bit hurried... I was meaning UFH in communal spaces and wet rooms downstairs. Interesting to read that it may not convect... I'm used to radiators that get very hot, heat the air and chuck it upwards. Our upstairs is always warmer than downstairs. May have to rethink my strategy (UFH in basement, and just hall and bathroom downstairs)

If you are going to put UFH in anywhere, put it downstairs, as the heat will rise anyway.

Got a quote online yesterday.... £1500 for 18months. They did ask me a load of extra questions as I've demolition, deep excavation, retaining wall and basement. They won't cover the demolition unfortunately.

Noob question, why do you need to mark on the pipe locations? Are you planning on drilling in to the screed at some point?

Ours is just on the IKEA adjustable feet. No issues, with the huge weight, it'll never move

Higher ceilings are really important in large open plan areas that are the fashion. The bigger the room, the higher the ceilings should be. We're going with 2.7m in most spaces and vaulted on the first floor.

Thanks @ragg987 I'm in Northern Ireland and building regulations and inspections are run by the local council. I'm assuming I'll need to contact a warranty provider and arrange inspections etc from the start?

Hi. I've been focusing so much on technical and design aspects, I'm off the reservation in terms of building warranties etc. What do you actually need in terms of warranties etc for mortgaging and insuring your house after completion and BC signoff? It will be unlikely I'll be using a main contractor, so won't have a warranty for the whole build. I'm building using raft founds, ICF, part basement, rest conventional. What do I to arrange to satisfy mortgage companies?

I was in a similar situation when building my brewshed. I spoke to my BC officer about it, and because it was classified as an outbuilding and not habitable space, he didn't care about it and wouldn't fall under his remit. Just said it would be installed to the appropriate standard by a competent person. I ended up extending an existing RCD ring circuit from an external socket at the back of the house. Used armoured cable and buried under the deck and lawn out to the brewshed. Couple sockets and a fused spur for a 5a lighting circuit. All works well, no issues. My neighbour who's a spark okayed it.

Speak to Kore. I'm 1.5hrs drive from their factory in Cavan, so transportation costs are minimal. But I have heard they are still competitive in the UK market. From my interactions with them, I'm impressed with their service.

I've done some digging. For a 100m² slab you are talking in the region of £35m² for insulation forms, delivery and design. For your hardcore, binding, DPM/ tanking, mesh, rebar, concrete & floating, you are talking £75/m², excluding initial groundworks. Remember you'll have less excavation, disposal and concrete costs compared to traditional founds. And you've no need for a secondary screed layer. (Northern Ireland costs)

The drawing shows the proposed dwelling being attached to the existing neighbouring dwelling? If you are considering a basement, proximity to existing buildings may be an issue, depending on soil conditions, your neighbour's attitude and planning policy regarding substructures. In regards to geotechnical investigations, you'll be wanting to drill bore holes to 50% beyond the bottom of the proposed basement. E.g 4.5m for single level basement. Geological Survey online maps will give you an idea of local ground conditions. They also have borehole logs, if luck you might find some that were done nearby. Basement construction costs start at approx double the going rate for ground level construction. E.g. if local rate is £2k/m², then budget £4k/m² for basement. Adverse ground conditions could potentially double or triple that number. We're doing a basement as well... But have advantage of a sloping site so will be a lot easier.

There's a standard way to price up a build - everything is categorised and you don't need to breakdown in to components e.g. there will be a line for internal carpentry, floor, electrical etc. Can't think of where it comes from but may be RICS. Have a search.

Yes. OSB 3 is perfect for the job. It should be covered by your roofing membrane on the tops and edges, underside should be ventilated.