Excavations in England and examinations of some more recent buildings have shown animals buried in wall spaces and under thresholds, or under hearths. Very ancient sites in Orkney have yielded ancestor burials under the floors of large dwellings - these seem to have been 'excoriated' by the time they were buried ie they were already skeletons when re-buried under the floor.
Cats are occasionally found stuffed into wall spaces, and larger critters like calves or lambs under floors, even in buildings dating to only 500 years ago. You can alos find phallic-shaped stones built into parts of buildings. However, there doesn't seem to be evidence for a practise of burying people alive under floors.
So I think what you have heard perhaps contains elements of folk magic / sympathetic magic - but if this was something that you believed in, if you were a Saxon or a Neolithic farmer, would you want the fairly annoyed spirit of someone you'd stuck under the lounge floor bothering you in your dreams?