There can be many sins buried under the floor or inside walls. Recently we uncovered the jumble of pipes when we lifted the subfloor to complete a bathroom renovation. There was a mixture of steel, copper and lead all tied together in a haphazard manner. Pipes were leading to nowhere, joints were rusting, drain lines were squished and a pipe ready to burst. A previous plumber had chopped through floor joists to run his drain line. In this case it was the wood plaster lathe from the ceiling below that as providing some of the structure for the bathroom floor.