Bitumen damp proof course. It’s pretty common to see these drop where they haven’t been supported. It’s a good thing for surveyors to check, with a camera as this can cause issues with sub floor ventilation. Long term you can expect timber decay and woodworm issues, as the floor will get excessive moisture issues. Some have previously made out suspended timber floor vents aren’t needed…. Not sure why they ever said that 🤷‍♂️#dampproofing #dampproofcourse #home #diy #renovation #builder #bricks