leviticus 14:48 And if the priest shall come in, and look upon it, and, behold, the plague hath not spread in the house, after the house was plaistered: then the priest shall pronounce the house clean, because the plague is healed. - Free Bible Online

      48-57. the priest shall pronounce the house clean, because the plague is healed--The precautions here described show that there is great danger in warm countries from the house leprosy, which was likely to be increased by the smallness and rude architecture of the houses in the early ages of the Israelitish history. As a house could not contract any impurity in the sight of God, the "atonement" which the priest was to make for it must either have a reference to the sins of its occupants or to the ceremonial process appointed for its purification, the very same as that observed for a leprous person. This solemn declaration that it was "clean," as well as the offering made on the occasion, was admirably calculated to make known the fact, to remove apprehension from the public mind, as well as relieve the owner from the aching suspicion of dwelling in an infected house.

JFB.