Maybe not the correct approach but maybe you could ask them to divert the down pipe into the sewer. Failing that I cant see what else you can do unless you raise your garden level.
Is it single skin? Could be moisture getting through the bricks then condensating on the roof. I think for ventilation to work well you need the air flowing just by the ceiling.
Isnt it a 1 in 40 fall to achieve a minimum of 1 in 80 allowing for joist sagging over time and deflection. As long as the roof is waterproof it wont matter. I cant see the BC guy checking the levels anyhow.
Be cheaper to fit a 2kw fan heater to use whilst in the shower. That will raise the room temperature a few degrees in a few minutes. Once finished turn off.
To be fair they could put planning in to attach the 2. They would 100% get it aswell as nothing really changes apart from a little gap gets filled in. This is a common technique some of the planners use to get big extensions under pd. The gap can be as little as you like, as long as there is a...
Lol caravan act. Outbuildings are built under class e permitted development rights. I've just secured one for a 12x7.5m garage but you need to submit the correct evidence.
Presuming the party wall 1 brick thick a cavity wall is going to protrude into the room. Either design the different wall depth into the kitchen, maybe fit a deep worktop and cut to 600 where required, or batten the wall off.