ETC

Escape windows can be lockable - not a great idea in my opinion but acceptable in ADB. Approved Document B vol 1 2019 edition inc 2020, 2022 and 2025 amendments and forthcoming 2026 and 2029 changes

Can you post some of your work that you have already completed for Forum members? - as an architect I would be very interested to see your work. Thanks. ETC.

Used to do that with worn listed building step treads…..just turn them over…hey presto new step.

I think I’d swop the WC and the sink over in the cloakroom.

Grand. 50mm air gap (or as near as possible) needed between the insulation and underlay. There are some underlays which say you don’t need ventilation but they do have some caveats.

Which way is this drawn? If the rafters are shown on a slope you will need continuous ventilation from the low to high end. Plus 50mm gap is normal.

How much do you want to spend?

Where will the toilet roll holder be?

I would always advocate full insulation below any gutter. Your detail shows a potential thermal bridge.

Speak to Kingspan or Trocal for a detail although I would assume that you would want to place your insulation above the deck and firing pieces.

Pump it….

Will the thermal loss be any greater than through the adjoining window?

Build a 100mm thick block wall either inside or outside the building.................then build whatever you want!

...................Or.................put plywood over the joists and then tapered firing pieces from front to back.

I do believe that the steelwork should be fire protected within a domestic floor where it supports an element of structure above - in this case a cavity wall. I don't think your BCO is correct if he/she is saying that simply enclosing the beams in the floor will give the fire protection.