Mr Punter

50 x 50 is quite big. Maybe 38 x 50 would still be OK. I would go with heavy duty galv nails 90mm. Either ring shank or smooth with the glue. There is still enough room for embedment for your nails on the (25 x 50?) horizontal battens. I would use 63mm stainless ring shanks for the horizontals.

I like internal thumbturn. Much safer in the event of fire.

I thought that if you did not have an airtightness test, the default was something like 15. May be different for conversions though.

Sounds fine to me.

I understood that your full plans approval notice should be legally binding for 3 years. If you received the approval and it did not mention this I would discuss with the head of BC.

Yes, silly idea. You need a footing for each post. https://www.wickes.co.uk/how-to-guides/garden-landscaping/plan-build-a-raised-deck

Stiff brush, jetwash.

If this is a new build you will need a lot more wall insulation. Also, the tanking slurry may well not keep it dry and does not seem to be for habitable basement space.

No, they don't normally in England except for flat entrance doors and (I think) connecting to garages.

It would be about an inch all round. Ask the supplier if the door would be suitable.

You might get away with Marmox Thermoblock for the chimney masonry but bear in mind the blocks have small columns of concrete (where they get their strength), so they are much better at reducing thermal bridging across the width than their height.

You could buy a 2032mm x 813mm door and have it cut down.

The Foamglas and Marmox will be no good for the high point loads of beams. You could use something like Armatherm or Farrat but they are specialist and probably £££.

The temporary habitation certificate is a Scottish thing. Here, you can move in when you want if you have satisfied planning conditions.

I think the material mix is highly engineered. Not just any old sand and cement. Also the process will be sensitive to environmental conditions - temperature, humidity, sun, wind, rain. I don't see it is a viable means of building low to mid range housing but I am sure with the effort going in to improve it there will be applications elsewhere.

Did the meter box come with ready broken hinges? I really hate the poor quality of the things.

The difference will be huge. The doors will be the weak point.

You could put it in level but I would prefer a very slight fall. Even 10 to 20mm over the length of drain would be fine.

He is not actually using a shovel, that is a broom. He is tidying up, bless him. He soon lost that habit.

Even if there is no mention in the title deeds, if the drainage has been in place for at least 20 years and you (or your predecessors) have not had to pay for use, you may have the right to use the pipe via prescriptive easement.

The soil pipe from the Geberit is 90mm so you need to fiddle about to adapt it to your 110mm.

+1 the Fischer ones are fairly cheap too. If you are using a Paslode first fix gun, get a "no mar" tip and make sure you adjust the depth.

The EA a fairly hopeless when it comes to communication or preventing illegal discharges. The system you have needs replacing. You probably need to focus on the total cost and how the cost will be split. If there are 5 properties, splitting 5 ways sounds logical. I am not sure where the "landowner" fits into this but as long as you have their consent to do the work on their land it should not be an issue. None of this will come cheap or be quick to resolve. Quite why none of this was covered when you bought the property is a separate issue that you could consider.

Just be a bit cautious as some policies have a right for the issuer to cancel if work is not completed in a timely manner. Check the wording.

I nominate this for the Buildhub "Best Mixed Metaphor". Love it!