09-01
2. BUILDING CONSTRUCTION
2.1 Types of Construction:
A. For each construction type, design fire resistive ratings of structural members in accordance
with NFPA 220.
B. Design the type of construction to comply with requirements of NFPA 101 for the most
restrictive occupancy in the building. For occupancies with no construction requirements in
NFPA 101, type of construction and height and area restrictions shall comply with the UBC.
2.2 VA Hospital Building System (Interstitial): Fire protection requirements for facilities designed
using the VA Hospital Building System (VAHBS) shall comply with the following:
A. Design walk-on decks in accordance with the lightweight insulating concrete assembly tested
and reported in NBSIR 85-3158, except that sprayed fire-resistive material protecting the
bottom of purlins supporting walk-on decks shall be sprayed to a thickness of one-inch with
fireproofing suitable for exposed applications. Wire mesh may be omitted from the bottom
flange of the purlins supporting the deck.
B. Steel in interstitial space supporting functional floors shall not be fireproofed, with the
exception of columns, which are sprayed throughout their entire height, and structural
members supporting mechanical room floors (required to maintain continuity of the two-hour
membrane separating interstitial spaces from functional floors). Clearly identify these
features on design details and in specifications.
C. Two-hour fire resistance rating is required between floors; the separation runs in a horizontal
plane along the mechanical equipment room floor, then vertically along the wall separating the
mechanical equipment room from functional spaces, then it continues along the interstitial
deck. Columns, girders, and trusses supporting more than one floor within interstitial spaces
and structural members in the mechanical room shall also have two-hour fire resistance rating.
D. Interstitial space need not be subdivided horizontally into fire or smoke compartments.
Horizontal exits or smoke barrier walls located below in occupied space need not be extended
up into interstitial space.
E. In interstitial space, a fire resistive rating is only required for two-hour fire rated shafts
(elevators, chases, stairs, etc.) and one-hour rated mechanical equipment rooms adjacent to
interstitial spaces.
F. Neither fire nor smoke dampers are required where ducts penetrate the one -hour rated
partition separating the mechanical room from the interstitial space; however, smoke dampers
are required at air handlers to comply with NFPA 90A. Fire dampers are not required in
ducts for openings in the interstitial deck less than 150,000 sq. mm (225 sq. in), including
supply ducts from interstitial spaces to functional spaces, exhaust ducts, and return ducts from
functional spaces into the interstitial space. Flexible duct work (UL 181, Class I) is permitted
in interstitial space for connections less than 2.4 m (8 ft) long and shall be no larger than 300
mm (12 in) diameter.
-4-
Previous Page
