(a) The provisions of § 29-269 shall not apply to detached one and two-family dwellings.

(b) The provisions of § 29-269 shall not apply to the renovations, additions or alterations to existing buildings above the street floor being converted to use group B, “Business Buildings”, as defined in the State Building Code, provided: (1) Each story above the street floor contains less than three thousand square feet of total gross area per floor; (2) the street floor is renovated or altered to comply with the provisions of § 29-269; and (3) the nonaccessible story above the street floor does not include the offices of health care providers, municipal or state agencies or passenger transportation facilities or offices located in airport terminals.

(c) Any building consisting of three stories or less, not otherwise exempted from the provisions of § 29-269 shall be exempt from said section if (1) each story above or below the street floor contains less than three thousand square feet of total gross area, (2) the street floor is designed, renovated or altered to comply with the provisions of § 29-269, and if applicable, § 29-273, and (3) the nonaccessible story above or below the street floor does not include the offices of health care providers, municipal or state agencies or passenger transportation facilities or offices located in airport terminals or mercantile facilities having five or more tenant spaces.