Another interpretation: "When a person has on the skin of his flesh" (Leviticus 13:2). It is hard before the Holy One, blessed be He, to stretch out His hand against this person. Rather, He forewarns him and strikes his house, as it is said, "And I will put a plague of leprosy in a house of the land of your possession" (Leviticus 14:34). If he repents, well and good; but if not, He strikes his garment, as it is said, "And the garment in which there is a plague of leprosy" (Leviticus 13:47). If he repents, well and good; but if not, they come upon his body, as it is said, "When a person has on the skin of his flesh" (Leviticus 13:2).
Why the Plague Strikes a Man's House Before His Body
Midrash Tanchuma Buber, Tazria 14:1
ד"א אדם כי יהיה בעור בשרו. קשה לפני הקב"ה לפשוט ידו באדם זה, אלא מתרה אותו ומלקה ביתו, שנאמר ונתתי נגע צרעת בבית ארץ אחוזתכם (ויקרא יד לד), חזר בו יפה, ואם לאו מלקה את בגדו, שנאמר והבגד (אשר) [כי] יהיה בו נגע צרעת (שם יג מז), חזר בו יפה, ואם לאו באין על גופו, שנאמר אדם כי יהיה בעור בשרו.