ETC

Strap the wall plate down with 30mmx5mmx1000mm long wall plate straps at maximum 2.0m centres. Install gable and ceiling straps at the same centres across three rafters/ceiling joists.

For what it’s worth: Steps are fine. Bottom should be flat - not sloping. I wouldn’t place concrete over the pipe - shutter either side and lintel over it.

That looks like an awful lot of work.

Not sure but wouldn’t think so. The ones I’ve seen sit on the ground floor slab. If you contact any of the precast concrete suppliers they will tell you what if anything you will need.

Any precast floor manufacturer will do precast stairs. Not rocket science and the manufacturer will measure on site and install the stairs.

Other than that?

Nope.

@Big Jimbo

By putting the stairs where I have shown may minimise the amount of demolition you will need to do plus it should get you to the highest point of the roof for headroom upstairs - just a thought.

Might be better with a DPC behind the outer leaf. Personally I’d have treated it in the same way an external door is - precast concrete threshold wrapped in DPC and then taken the DPM across and up the back face.

Very smart.

No great tbh. Bit disjointed. You’ve got all the right bits but not necessarily in the right order. Give me a shout if you want me to take a look. Also what does it look like? Is there a bit of pitched roof and a bit of flat roof to the back? Strange kitchen layout - might need a bike to get from one end of the units to the other. Utility is too small. Little to no storage. Try putting furniture on the plan.

Why don’t you pump the cavity/ Also how are you getting cover to the bottom of the mesh? Why have you got a DPC cavity tray?