Mr Punter

What connects to the bit circled blue?

No issue at all. Doormats can be 20mm thick. You would not notice the staircase unless it was more than 20mm out.

Did you identify the pipe on the water company sewer plans? If so, it would probably be a water company sewer and as your connection was made on your own land you would not need an easement. You need to be very careful with ownership, rights and easements as it is easy to fall into various traps.

At a guess, £100/m2. At least it is easy access. I know a bricklayer who uses a piping bag and can get a fair bit done. If the wall always looks that wet, you have some drainage issues.

Mostly boundaries are defined by buildings, walls, fences, hedges, ditches and roads. How much land do you think they are planning on stealing?

I thought self build was exempt?

I have had these both as owner and adjacent owner. They do not define boundaries, although some attached drawings may indicate them. They often have photos of the boundary areas. Is someone after nicking your land? You could get a topo survey done that would set the current location of everything.

You could just get a SE to look. They won't charge you much and you need one anyway.

If you are getting a main contractor to build this, you will need between £300k and £500k all in. If you do lots yourselves you could come in under £200k.

The strings are the same with but the stair is packed off the left wall and has had capping to cover the gap. No concerns about what it looks like underneath. Looks a bit rough. I can see why you are not thrilled. That will take lots of work to finish.

With mineral wool batts the wall ties are normally placed every 2 block courses, except for near openings where they are every block. He may be going for pushing the batts over the wall ties before building the outer leaf, but it is not the normal way to do it. Ask the Building Inspector to have a look and see what they say. Like @Spinny spotted, the location and scaffold look rather bizarre.

You need to play this from where you are and not look to assign blame. Is there any way the design of the window could be modified to comply with Building Regs? If you post up a floor plan you may get some useful suggestions.

This does not sound like a planning issue. Planning do not deal with ownership or boundary disputes. The blurb in the consent relating to Party Wall Awards is just an advisory note.

I am afraid this will be a legal matter. Your buildings insurance may cover the cost of this. If they have built over your land it is trespass. Send them a letter explaining that it is not acceptable.

It would need a clear opening width min 450mm, which is a lot for an oriel window. Can't you have the main part opening to comply?

Any water in the cavity low down will go down to the foundations and drain away.

Before you talk to your neighbour, work out what you are after. Let them see the wall damage and let them know that you think it may be due to their tree. If all goes well you could suggest that the trees are removed. You will need to listen to what they say and gauge their response. If they are hostile, just be polite and seek further advice.

I am no expert. I let the assessor know what the planning condition was and they did the SAP calcs to suit. The SAP should have Target Carbon Dioxide Emission Rate (TER) and Dwelling Carbon Dioxide Emission Rate (DER). I think your DER will need to be at least 10% less than the TER.

I don't understand why you need a 6 x 2 to make up 5-10mm? Neither does the cat.

Given the low first floor window cills you are probably going to end up with a flat roof. You could build your roof up higher than your neighbour, putting the insulation on top of the decking. If your neighbour wanted to do theirs at the same time it may work well, but not essential.

Willows are very high water users and if you are on shrinkable clay soil it can dry out and cause the foundations and walls to move and crack. Talk to your neighbour and perhaps look at getting legal advice.

Stairbox and a chippie to fit it.

I am building some new flats and have installed DMEV fans, which, together with trickle vents and wall vents will provide ventilation. I am about to get an air tightness test. The design stage SAP is stating 4.0 design value for air permeability. What if the testing shows 2.0 or 10.0?

Just have normal weeps above the cavity trays over lintels. I don't know why you need them at low level.

From the photos that was seriously poor. I think that @ProDave has Rationel and is in Scotland. I have had IdealCombi and Velfac, but I think some of the Velfac front doors are Rationel. All part of Dovista.