Mr Punter

Three on the inner course seems excessive, especially with the cladding. I think you can send the drawings to Visqueen and see what they suggest (normally fairly OTT though).

Hi @Alan and welcome. Before your architect does their detail drawings, make 100% sure that your warranty provider and building control are happy with an ICF basement.

I have had some fantastic sound test results on timber frame party walls. Even the standard Robust Detail gives fairly good results.

If it is just that wall, would it be out of the question to clad it? Could use oak, clay tiles or natural slate?

Can you not have a window mounted fan, as the window can be set into the wall a little. If the window is inward opening you could access the fan for servicing or replacement.

Build the wall in 140mm blocks. They are better if you need to cut deep chases as well.

If the site is within the settlement boundary and house prices in the area are over £3500 per m2 it may be worth demolishing the existing buildings and gaining consent for, say, four new houses.

Bear in mind that plywood is often 1220 x 2440. If you can get it metric sized it will save a trim-up.

I have seen this happen a fair bit in France. Much better results than trying to fix something which is inherently defective.

It is really difficult to get it to fit as sometimes the studs are a bit thin or the boards are thick. Use 130mm or you will struggle to get the plasterboard on.

Making this a u shape means you have a very high external wall to floor ratio so no chance of it being very energy efficient. It also complicates the roof design.

Check with your warranty provider and building inspector for the required spec. Flat roofs are a big source of claims. There is no standard covering for flat roof. Can be felt, single ply (lots of types), liquid, fibreglass or GRP. It may be easiest to have thin deck on your joists, then firrings to fall direct to outlets (no box gutter), thin deck and insulation then deck to take the waterproofing.

Will smoke from the BBQ not blow into the house?

Perhaps look at reducing the number of dormers and increase their size. The one that cuts through the floor zone looks a bit odd. Could you add windows to the gable ends?

If you have a parapet all round you must have 2 outlets. Why not scrap the box gutter and just direct the roof fall to the outlets? What is the proposed roof waterproofing?

Can youpost a site plan showing the road and neighbouring properties?

Sometimes you have to double up or use a glulam or two. The 5.4 is a fair span.

Make the house airtight and well insulated - especially the ground floor - and add MVHR and the space heating costs can be reduced to the point where ASHP v gas will make little cost difference. The gas boiler / heat pump can be swapped later but the insulation / airtightness / ventilation is a far bigger job. A single ASHP should be fine for both floors.

Before you make the final decision, bear in mind that Trespa is one of the cladding types being removed from high rise due to flammability and although this will not apply to your project, insurers are very risk averse and may change their criteria in future. The oak frame garages often have brickwork to the lower section and oak cladding above, with clay roof tiles. You could also look at slate. If you want to convert it in future make sure you buy one designed for this. There are loads of companies who manufacture and supply the kit. Sometimes it is worth giving a few a call and having a chat, as you do not always get the information you are after from their websites alone.

Just awful. Get a proper leadworker in to redo it.

Kytun do retrofit ones as well. I guess you would need to fix to the render with CT1 plus mechanical fixings (stainless screws?) every 800mm of so. https://www.kytun.com/p/retro-fit-tile-dry-verge-alu-50mm-blue_black-24m/c08esbb

Yes they have a standard for housing, flats and commercial. You could also add your own loadings if they were extreme. Normal stuff like water tanks are easily dealt with locally but you can adjust for thick screeds, heavy equipment etc. JJI do Joistmaster software you can download. You can adjust joist size, deflection etc and it gives you acceptable joists and even price per m2. Make sure you let a "proper" joist designer do the final design as you may have omitted something that could come back and bite you.

12mm is acceptable for the housebashers but if you are a self builder, get a quote for less than 8mm deflection if you want a really solid feel to the floor.

As I have suggested previously, if you specify that you require maximum 8mm or 0.002 x span (whichever is least) deflection there will be no issues with bouncy floors and the cost difference is fairly small. The standard you will be offered is 12mm or 0.003 x span which is crappy.

I have used aluminium standing seam on projects and the panels zip together over halters that prevent uplift but allow expansion. You need Rockwool under the panels or you can hear the noise from the expansion / contraction. The centre of each sheet is mechanically fixed so it does not creep over the roof.