Bricklaying & Repointing

Giant hole in concrete floor

Anonymous user 15/03/2024 - 2.54 PM

I have a house built in the 50s. Today I was lifting the old laminate flooring ready to have carpet laid. Too my horror I uncovered numerous loose bits of concrete only to find large voids underneath. It’s hard to describe without pictures. I have a large floor to ceiling height window that is installed onto the outer brick wall. I removed the loose concrete flooring around the window frame, only to uncover a large void between the original concrete base and the outer brick wall. The void was just filled with loose sand and stones - I don’t even understand how they managed to create the thin concrete ledge to hide it. Any ideas how I can fix this? Has anyone ever heard of this before ***** Update ***** Thank you for all your help and guidance. It was the cavity wall being exposed. The thin concrete that covered had crumbled away over time. I completely removed all the concrete along the window frame, dug out the loose sand rubble mix layer some damp proof coursing, and then filled with concrete. After a few days I then skimmed a thin cement top ready for the underlay to be laid. Again thank you for all your help.