Changing Construction Type

Q: We are looking to construct a surgery center which will be classified as Healthcare Occupancy on the third floor of an existing five story building which is classified as Business Occupancy (mainly doctor offices). The surgery center will be connected to an existing hospital with an enclosed bridge and will be servicing more than three inpatients from the hospital (via the bridge) and outpatients, but will have no overnight stays. The existing five story building is fully sprinklered, and is a Type II (000) construction. All elevator shafts and stairs are 2 hour fire rated. Our strategy for the surgery center, which is on the third floor is to change the construction type of the first through the third floors to a Type II (111) and keep the upper two floors as Type II (000). In addition we would provide a 2 hour occupancy separation between the third floor and the adjoining floors. Do you believe this meets the intention of the NFPA 101 Life Safety Code?

A: No… I do not.

You plan on having Type II (111) construction type for the first three floors which is business occupancy for the first two floors, and healthcare occupancy for the 3rd floor; and then you plan on having the fourth and fifth floor remain as Type II (000), which will be presumably business occupancy.

Even though the two different construction types will be separated horizontally by a 2-hour fire rated deck, this is not permitted for healthcare occupancy. According to NFPA 220 (2012), section 4.1.2,  where two or more types of construction are used in the same building, the entire building shall be classified as the least type of construction in the building and shall be subject to the requirements for that type. Since you will have Type II (000) construction on the 4th and 5th floors, that makes the entire building subject to Type II (000) construction and according to 18.1.6.1 of the 2012 LSC, Type II (000) construction is not permitted in stories greater than one for healthcare occupancies.

To effectively separate buildings (and their construction types) you need to have vertical fire-rated barriers that extend from the lowest level to the roof. Horizontal 2-hour fire-rated floors is not an acceptable separation barrier concerning different types of construction.