Mr Punter

It is probably best not to get your friend to fiddle with the commissioning settings. Maybe ask the engineer when you get back or when they service the unit.

They do the 5mm washers which I have used in the past. They also do a 50mm offset in the downpipe but that may not work for you. Alternatively, could you carefully grind out the part of the projecting string course that is in the way?

Yes you need trickle vents, then replace the defective sealant.

You may need to derate the cables. I have ended up using 4mm for sockets where we had to run through insulation. Get the sparky to work it out or I think you can look up online.

I think you will be really pleased with this when it is finished. I hope the lift up units have servo drive or you won't have spent enough!

MVHR is only doing ventilation and has almost no impact on heat distribution, so just look at the UFH. Splitting living and bedrooms into 2 zones is fairly common. It means you can control the timing and temperature separately by zone.

Be aware that with timber frame and brick / block outer leaf the installation has to take account of differential movement, so over time the gap at the head of the window will open up and the cill will close up, especially on upper floors. This is where the likes of Compriband are very handy.

It is quite possibly asbestos cement.

Because yours is a flat it will be less sought after. I would do it up to mid spec and sell to someone who wants the location at a (relatively) keen price. You have already had your pants pulled down by the architect. Don't go back for more. I see there is a house nearby https://www.rightmove.co.uk/properties/131305742#/ and that is asking price and unbroken freehold house.

I have heard this can happen but I cannot work out why you cannot create a few leaks and have it re-tested?

Based on these I would not recommend you go ahead. Find somewhere above ground and damp free.

Often you can but it is worth doing a condensation risk analysis.

I have used Fermacell instead of plasterboard. It holds a screw really well. It is an absolute pig to use though and expensive. Heavy and difficult to cut. It is sometimes used double boarded in prisons as it is very tough.

Yes 50mm 5s are fine, as is one per block. Wall plate would have been better half lapped but it is done now.

Galvanised

You could have inward opening with external shutters. You will need planning consent as it is listed.

Spring toggle fixings can work well.

OK I get you. Yes I assumed vented because I normally focus on new build.

I guess it would still vent either side of the ridge board in any case. You don't need ventilation from one side to the other. You probably don't get much anyway, as the airflow will go up to the highest point then exit but I agree the flat ceiling area is worth doing.

Party wall and boundary wall issues are rarely clear cut and often a source of dispute. It is not easy to establish whose land they are built on, who is responsible for repair etc. What are you hoping to achieve? There is a website at https://www.gardenlaw.co.uk/phpBB2/index.php where people discuss this in minute detail.

It is fine to insulate right up to the apex. One benefit of having a flat area can be that lights are easier to place. It is good to have a small amount of PIR under the rafters as well to prevent cold bridging. 40mm helps a lot and it reduces the risk of condensation on the rafters.

It is better to show the windows in the context of the elevations so they can work out distance from FFL and what security is appropriate for part q compliance.

These sometimes support the upstairs landing. Have a look at a neighbours and see what theirs is like.

I would not want a branch connection under the floor. I prefer the below slab runs to be as short as possible. I would be tempted to move the line from the store so it heads under the stairs. Makes it shorter and you lose an IC. From your kitchen, you could have a gulley outside that would be trapped and roddable and take the condense from the ASHP. That way that bit of the line can't bring gasses into the house.

I suspect if it is clad in non-fire treated timber, a cavity barrier won't do a great deal.