In my new house we're proposing to have a basement. The plan is for the basement walls to be constructed from block/precast concrete, tanked on the outside and then insulated with a thick layer of EPS insulation. The basement slab will be laid on top of a layer of insulation, with slab and wall insulation meeting up around the outside. So far, so good - good performance, no thermal bridges etc.
However, for safety purposes we need to have an emergency escape route that doesn't involve the normal stairs, which basically means an escape well. See (hopefully) attached diagram for a plan view.
The question is how best to construct this to minimise thermal bridges between the main wall structure and the exit well, stop ground water filling up the exit well and maintain the tanking around the walls of the main structure.
I've looked in the PassivHaus details book, but there isn't really anything similar. or that is obviously easily adaptable.
Any ideas or thoughts are very welcome.