» All sprinklers need to be quick-response standard spray or extended coverage pendent or upright sprinklers. » The ceiling height cannot exceed 20 feet. » The maximum spacing and area of protection cannot exceed the maximum spacing requirements for light hazard occupancies provided in Table 10.2.
The answer, like so many great engineering answers, is “it depends.” Experience and testing have shown sprinklers to be effective and necessary at heights in excess of 50 feet. For this reason, most installations should not have a limit on the height they can be installed.
The 18-inch applies only to areas that have sprinklers installed. Picture a horizontal plane parallel to the ceiling that is 18 inches below the sprinkler heads. Nothing should be in that area between the bottom of the sprinkler heads and the imaginary horizontal plane parallel to the ceiling that is 18 inches below.
The answer is that you should follow the general obstruction rules of NFPA 13. For obstructions below 18 inches for standard pendent and upright spray sprinklers this means that as long as the obstruction is less than 4ft (1.2 m) wide that it is not considered an obstruction.
To comply with NFPA 13, sprinklers are required above the obstruction at a distance not less than 1 in. and not more than 12 in. from the ceiling above, assuming unobstructed construction.
Buildings must be residential, four stories or less, 60 feet in height or less, and not use any code exemptions for an NFPA 13 system in order to use NFPA 13R.
This includes residential occupancies that are up to and including 4 stories in height and located in buildings not exceeding 60 ft (18 m) in height above grade. If it falls within this criteria, then NFPA 13R can be utilized for the protection.
NFPA-13 states that sprinkler protection is NOT required above hung ceilings if the area above has non-combustibles even with small openings in the ceiling.
1.3 lays out the “Three Times Rule” which states that unless specific requirements are met that “sprinklers shall be positioned away from obstructions a minimum distance of three times the maximum dimensions of the obstruction”, up to a maximum of 24 inches (0.6096 m) though the “maximum clear distance does not apply ...
Types of sprinkler systems permissible by NFPA 13, Standard for the Installation of Sprinkler Systems, are wet, dry, preaction, and deluge. Other types of extinguishing systems, such as clean agent or water mist, are addressed by other standards.
Distance from Ceiling: minimum 1", maximum 12" for unobstructed construction. The minimum 1" is typical; however, concealed, recessed, and flush sprinklers may be mounted less than 1" from the ceiling and shall be installed based on their listing.
(1) Provide and maintain 12-inch clear in back to walls or any other obstruction, 18-inch clear on each side, and 36 inches clear in front of all riser piping, equipment, and appurtenances.
They provide protection for the sprinklers - making them less prone to accidental knocks, tampering, and the potential water damage that can result. They simplify sprinkler design at clouds and other design features as the sprinklers are located above the dropped ceiling.
In a nutshell, NFPA 25: Standard for the Inspection, Testing, and Maintenance of Water-Based Fire Protection Systems says that objects that can block a sprinkler's spray must be at least 18 inches away from the deflector.
Light Hazard (10-15 ft). Excluding heads in combustible concealed spaces, all sprinklers in this category have 15 feet (4.6 meters) of maximum allowable spacing between them. Ordinary Hazard (15 ft). All sprinklers in these environments have a 15-foot (4.6-meter) maximum.
NFPA 13R further lowers costs by permitting a potentially lower level of water discharge than NFPA 13, which may result in smaller pipe sizes. NFPA 13 also calls for a greater density and spacing for sprinklers, as well as attic requirements that can significantly drive cost.
3 of NFPA 13, the spacing advantage of the small room rule is that designers may pick one wall and space sprinklers up to 9 ft. away from it. For the rest of the walls, the 7.5 ft. max spacing rule must be followed.
(32) In no case shall the distance between sprinklers exceed 12 ft (3.7 m). (3) It shall not be permitted to move a branch line where there are moved sprinklers on a branch line that exceed the maximum sprinkler spacing.
3.3.25* Ceiling Pocket. An architectural ceiling feature that consists of a bounded area of ceiling located at a higher elevation than the attached lower ceiling.
Do not install cable trays, heating ducts or other large obstructions closer than 3 times its width, to a sprinkler head. (i.e. if the duct is 2 ft (0.6 m) wide, then it should be 6ft (1.8 m) from the sprinkler head.)
In areas where sprinkler systems aren't ideal for extinguishing a blaze, OSHA requires automatic fire suppression systems. Follow these regulations: Install systems that use extinguishing agents approved to fight the specific fire hazard in the immediate vicinity. Inspect fire suppression systems regularly.
The biggest difference between the three versions of NFPA 13 is the audience they serve and the allowable omissions within 13D and 13R. NFPA 13 and 13D focus mainly on life safety and property protection, while NFPA 13R strictly focuses on the life safety aspect.
NFPA 101 – Life Safety Code: Headroom is generally required to be at least 7 feet 6 inches, however, projections are allowed as long as a minimum of 6 feet 8 inches of headroom is provided at these projections. The code states that the measurement is taken from the finished floor and allows a tolerance of -3/4-inch.
a) When balconies and terraces are provided, regardless whether or not there is an exterior projection (roof, overhang, balcony, terrace, etc.) above, sprinklers are required that cover the entire deck.