Negaim 13:4

A quarantined house conveys impurity from its inside; one that has been confirmed as unclean does so from both from its inside and its outside. Both convey impurity by entering them.

Negaim 13:5

If someone built stones from a quarantined house into a ritually pure house and the nega returned to the quarantined house, the stones must be removed. If the nega returned to the stones, the first house must be demolished; the stones continue to serve the second house while the signs of nega infection are being observed.