improved property
(2) As used in this section, the term “improved property” means a detached, single-family dwelling, construction of which was begun before June 8, 1976 , which is used for noncommercial residential purposes, together with such additional lands or interests therein as the Secretary deems to be reasonably necessary for access thereto, such lands being in the same ownership as the dwelling, together with any structures accessory to the dwelling which are situated on such land.