Unless it's a "work for hire" (typically stipulated in the contract with the designer/architect) you cannot simply duplicate it and use it to build a new house without potentially running afoul of Copyright Laws.
17 U.S.C. Sec 101 (definitions): "An “architectural work” is the design of a building as embodied in any tangible medium of expression, including a building, architectural plans, or drawings. The work includes the overall form as well as the arrangement and composition of spaces and elements in the design, but does not include individual standard features."
17 U.S.C. Sec 102:
102. Subject matter of copyright: In general28
(a) Copyright protection subsists, in accordance with this title, in original works of authorship fixed in any tangible medium of expression, now known or later developed, from which they can be perceived, reproduced, or otherwise communicated, either directly or with the aid of a machine or device. Works of authorship include the following categories: (1...7) 8. Architectural Works.