D.C. Code § 40-303.12

In case of labor done or materials furnished for the erection or repair of 2 or more buildings joined together and owned by the same person or persons, it shall not be necessary to determine the amount of work done or materials furnished for each separate building, but only the aggregate amount upon all the buildings so joined, and the decree may be for the sale of all the buildings and the land on which they are erected as one building, or they may be sold separately if it shall seem best to the court.