i took some pictures to see if it will shed some light. sorry i should have clarified the system. i know the halls and landings and everything underneath the carpets and wooden lino stuff is indeed concreted.
i think i have uploaded them properly to my album:
//www.diynot.com/network/cache/albums/23869
i think i have uploaded them properly to my album:
//www.diynot.com/network/cache/albums/23869