CHAPTER 674 LOCAL LAND USE PLANNING AND REGULATORY POWERS
Zoning
Section 674:19
674:19 Applicability of Zoning Ordinance. –
A zoning ordinance adopted under RSA 674:16 shall not apply to existing structures or to the existing use of any building. It shall apply to any alteration of a building for use for a purpose or in a manner which is substantially different from the use to which it was put before alteration.