Residential mortgage means:
(1) A transaction that is a covered transaction as defined in § 1026.43(b) of Regulation Z (12 CFR 1026.43(b)(1));
(2) Any transaction that is exempt from the definition of “covered transaction” under § 1026.43(a) of Regulation Z (12 CFR 1026.43(a)); and
(3) Any other loan secured by a residential structure that contains one to four units, whether or not that structure is attached to real property, including an individual condominium or cooperative unit and, if used as a residence, a mobile home or trailer.
17 CFR § 246.2
For purposes of this part, the following definitions apply: