Bad enough to put your foot through ? A friends workshop has some planks on the floor which were a trip hazard for us. I went to move them to discover a hole stepped backwards and my foot went through the floor board behind . He then explained , somewhat sheepishly , that was why he put the other loose boards down !
His 1.5tonne metal lathe sat on a concrete bed ( he cut a hole in floor out in shuttering and rebar and poured the concrete in situ before the lathe was lifted in via the roof . Squirrels nesting in ceiling did not help matters
