Mr Punter

I am not sure if it would be feasible to trim and modify the trusses and have them sit on the bottom flange of a steel beam so that the original ceiling height is maintained throughout?

The Velfac / Rationel / IdealCombi family of composite windows all like a gap around the window of about 10mm which get filled with Compriband expanding tape. If you are rendering, you need to get the render on before you measure and fit the windows. Not too difficult. This leaves a nice space inside for insulated plasterboard. If you go for an all ali window the u-values can be pretty poor.

I assume that it is B1 that is an issue, so nothing to do with bifolds? The span for the knock through is really wide and needs a deep beam to provide support. 400mm drop down into the room is a lot though and I can imagine spoils the open look. Perhaps a bit more thought at the design stage would have given a better solution.

Is this not the side elevation, flipped and with less detail? Just send the drawing.

You could just time how long it takes to fill a 5 litre container with the kitchen sink cold tap on full.

You would do well to check the pressure and flow rate of the incoming main, as that will be a limiting factor in the performance of the combi.

With your drainage, the pipes need to go right through the blocks.

You mean the Teplo basalt ones? Crazy expensive.

600 for external walls means more space for insulation.

I don't really believe in the cleaner. Just leave the expanding foam can attached to the gun at all times, even when it is empty.

A 2mm indent is not a proper frog. These should not be more difficult to lay. If there are lots of cuts you can hire a wet cut masonry saw. 91N/mm2 is not the density it is the compressive strength. How much was the original brickwork contract and how much more do they want?

No membrane required, but you need to restrict the amount of moisture getting into the outer leaf, so either render for blockwork or a coat of Stormdry or similar if it is brickwork.

What did the Party Wall Award say? As the Building Owner I am afraid you will rarely have it easy. I think you may need to take this one on the chin. Perhaps politely ask the other sides surveyor if they would consider a reduction in their additional fee on the basis that the request was rather late in the day.

With TF 90mm often seems to be acceptable for steel bearing. Maybe it is because TF used to be 89mm everywhere and still is for internals and party walls.

The issue when the tree is dead is clay swell / heave but unlikely after 2.5 years. Get the stump ground out and bridge over with reinforced concrete ground beam to SE design.

The crack looks fairly minor. Some sand cement to match existing carefully filling the crack and maybe some matching aggregate pushed in. Point up the joints in the cills and a lick of paint.

It is Building Regs that covers this. You really need a quote from a builder for this or you could find out if the seller has any? Unusual to get planning consent and not get a quote for the works.

Boiler flues are either fitted to a fall or have a built in fall, so there should not be an issue with water getting into the boiler this way. The soil pipework looks a right bodge, but perhaps it is work in progress and hopefully gets properly finished, filled and painted as it looks an eyesore from your side.

It all looks fine. The vent pipe needs to extend up further. What is it to you?

I do sympathise with @muzgabrak. I still can't comprehend why so much of the metalwork in windows is not even corrosion resistant.

This is probably a standard install in the plastic glazing trade. Not pretty but FENSA and GGF will probably not come to your rescue. A can of low expansion foam or some mineral wool will help.

It would be best to start working part time on this and get income from your other site work. If you buy the right site at the right price you are 70% of the way toward a decent profit. Spend most of your time looking for sites that will be a bargain and work out the angle and resale values. If you over pay for a site you will never make money and will probably lose. I know because I have done it. Lots of people have made money from developing because market values have increased. This is no longer the trend. Having a trade and knowing others who are good helps a lot as well.

I think if the surface is nice and flat you don't need mortar but if it is less even, like brickwork frog up, you do.

The Hi Therm lintels have a fairly long lead time and are quite a bit more expensive. I can't work out from the picture what has been used. If they used a separate lintel for inside and outside leaf they will be just the same thermally, but just more effort to build with.

Mask, goggles and cut with a handsaw. I like to use a nail and a straight edge to mark the cut line on the foil face. Foam any gaps.