Dave Jones

don't see why not, subframe/cavity closer certainly wouldn't stop them.

Building control should pull you up using underground soil fittings inside. Cable tieing water pipes to the soil stack.. hope thats temporary. Any reason you went for metal over timber apart from making life difficult for all the follow on trades ?

for a normal 300mm wall, have a 290mm (to hide the joint) plate welded to the steel to sit the ourside brickwork on. The SE should be speccing this anyway.

be aware those plans are +/- 100m! Cant trust them at all, if you are hand digging it wont be a problem if you are using a digger get someone who has done it before.

they have to be built in yes. Once you have the floors screeded build them into the stud. Try and use stud internal walls rather than block so you dont wast space as you will have to box them out which looks a bit gash.

cavity closers are plastic with insulation stuck on them. Much better to use subframes from the outset so the brickies can build them square.

normally insisted on if you want to borrow money for the build.

don't rush into this. heat pumps are expensive to install and expensive to run, more so on older buildings. You may be better off financially and heat wise with economy7 night stores. Heat pump install at circa 10-15k will pay for a lot of electric before you see any payback. Not to mention without thourghly insulating and having massive radiators (treble the size of normal ones) you will be cold.

should be workable, 2500 min downstairs 2400 up gives you 1800 to ridge .

those are oppressively low. Better planning at the outset can help with this.

it boils down to, do you need warranty or not. if not local authority as they are the least interested in hassling you.

as long as you have a min of 12/13mm /M fall then just make both runs work to the final manhole. May need to drop one a little more or move the chamber closer etc.

2600 down 2400 up

Ive found BC to be very flexible with soakaways, they will let you have some scope to site it if its a tight site.

yes this is probably easiest way nail to the side of the noggins to bring it down to all the same height.

talk to your local tile giant or equiv store they will give you couple leads.

for such a tiny amount barrow it.

something about building that brings out the worst in people.

surely there is a volumetric wagon local to you to save all that messing about.

dont think there is anymore to add.

the difference is a tray has a weeper to allow the moisture out. All i am saying is that's what's required for regs to do the job properly, with diy you can do what you like and your pipe may be fine who knows.

sounds worse than it is, a day with a micro digger with breaker and the old floor will be out. half a day to insulate and dpm then you ready for underfloor and screed.

better off with the digger, you have the wrong size dumper for it. too big. you need a 1 ton, have a look at the muck truck wheeled they are much easier to move than a tracked machine. https://www.sandhillplant.com/ this guy has some nice ones.

used https://www.lightingforgardens.com/ they are very good quality, register with them as a builder(self) they will give you 20% off their web prices.

because it costs pennies to do and can save thousands. You could use the same argument for roof tyvec under the tiles, why bother if the tiles are providing the protection ?