N.Y.C. Admin. Code § 27-116: § 27-116 Alterations between thirty percent and sixty percent of building value.

If the cost of making alterations in any twelve month period shall be between thirty percent and sixty percent of the value of the building, only those portions of the building altered shall be made to comply with the requirements of this code, except as provided in sections 27-120 and 27-121 of this article.