Mr Punter

If it is a party wall you have a right to enclose it on your side and use the party wall as part of your structure. Yes, may need to serve notices if you need to cut into the wall or raise the height, but check very carefully that this is the case before you serve the notices as once the process begins it is difficult to stop. You could suggest a sweetener to the neighbour, such as cash payment, should they consent to the works in the notice. They will also need to be satisfied that the works are fully insured.

Same as any foundation. 100mm shingle bed, then shingle to crown of pipe, backfill with selected dug material or imported fill.

What is the purpose of the proposed membrane? Is it a Nudura standard detail?

Steel frame will probably be the best option. It could be erected with a lorry mounted hiab. Is there decent access?

Why not membrane tight to the walls, then batten?

Sorry to read of this. A section drawing through the wall and roof would help. Is this the only damp spot, or is it elsewhere?

+1

I am not sure if you need to serve notice under the PWA but if you have, the process has started. It is best for you if you both use the same surveyor. The Award will take about 6 weeks. If you have not served notice, you could just go ahead. The neighbour would have to get an injunction at the High Court and may be liable for costs if they were unsuccessful.

Try https://images.reading.gov.uk/2022/11/ID95-Site-Layout-Planning-for-Daylight-and-Sunlight-A-Guide-to-Good-Practice-BRE-2022.pdf

"2.1 The assessment comprised the application of the method given in the Building Research Establishment publication “Site Layout planning for daylight and sunlight. A guide to good practice” Second Edition, P J Littlefair 2011." So it compares existing and proposed daylight and sunlight reaching each window. Sunlight is broken into annual and winter.

I last had one carried out 10 years ago for £720 + VAT. It was only the impact on nearby properties. I can PM details if you want.

Yes that intumescent paint is horrible stuff. Goes yellow and seems to encourage rust.

We asked for this from the seller of a plot, where they had already got outline pp. The whole area had similar non development covenants dating from the 1930s but were never enforced. They are often used during development / sale of new estates to protect the sale values.

I don't really see much expanding foam on Velux. Normally rigid insulation and plasterboard around the reveals.

It is a shame and I can see why you are disappointed although most people would not notice and it will not affect the performance of the roof. You appreciate that this is a total pain to remedy - it is not a bit of minor snagging. Would you consider a reduction in the cost would be a sufficient remedy?

One issue will potentially be the weight of the stone slips on a timber framed structure. If you are doing rainscreen cladding on a timber frame you need a minimum 25mm strongly vented air gap between the sheathing and the cladding. I think you should be looking at a proper system with BBA approval.

You could run the last bit in 150mm pipe at 1:150 if the connection at the sewer end is sufficient diameter.

This looks like water running off the paving into the channel. Can you cut a wider channel and fit an ACO type channel drain?

I am not a great fan of external floor level the same as internal FFL. Possible damp problems. Externally you need a bit of cover over the drains but on your drawing they could be run just under the external slot drain. If there is any way to avoid a pump station - even if fall is reduced to 1:80 - then do that. Is this Polarwall icf?

It is worth bearing in mind that @nod is a seasoned contractor /developer who works very hard and efficiently and has lots of contacts as well as free labour from family and friends, so don't for a moment think you will get your project completed for anything like he can. For normal humans in the South East, £3-3.5k / m2 seems about right.

How did the water get there? Was it through ducting or pipes or does it just force its way out of the ground? I would hope your floor level is much higher than external ground levels.

Part M is for new dwellings. As long as you don't make yours worse you are fine. I would be wary about a drain blockage allowing water into the flat in heavy rain, so a decent threshold would be my choice. A circa 150mm step up or over the door threshold would be good.

I doubt this would be noticeable once the carpet and underlay are down.

Good result. Will they need to trim the studs so they are the same height as the others?