I have a single storey office built 2021, 180m2 divided into two, sole occupation just office use, reception, wc and meeting rooms to the front, brick / block wall with fire door through to the rear open plan office with fire exit. The roof void is open no compartmentation in place, have tried to fathom out whether this requires compartmenting looking at Doc B I don't think it does, any advice would be greatly received. 😎