Sloping Ceilings (Peaked and Shed).
17.7.3.2.3.1* In the absence of specific performance-based design
criteria, smooth ceiling smoke detector spacing shall be a
nominal 30 ft (9.1 m).
17.7.3.2.4.2 For level ceilings, the following shall apply:
(1) For ceilings with beam depths of less than 10 percent of
the ceiling height (0.1 H), smooth ceiling spacing shall be
permitted. Spot-type smoke detectors shall be permitted
to be located on ceilings or on the bottom of beams.
(2) For ceilings with beam depths equal to or greater than
10 percent of the ceiling height (0.1 H), the following
shall apply:
(a) Where beam spacing is equal to or greater than 40 percent
of the ceiling height (0.4 H), spot-type detectors
shall be located on the ceiling in each beam pocket.
(b) Where beam spacing is less than 40 percent of the
ceiling height (0.4 H), the following shall be permitted
for spot detectors:
i. Smooth ceiling spacing in the direction parallel to
the beams and at one-half smooth ceiling spacing
in the direction perpendicular to the beams
ii. Location of detectors either on the ceiling or on
the bottom of the beams
(3)*For beam pockets formed by intersecting beams, including
waffle or pan-type ceilings, the following shall apply:
(a) For beam depths less than 10 percent of the ceiling
height (0.1 H), spacing shall be in accordance with
17.7.3.2.4.2(1).
(b) For beam depths greater than or equal to 10 percent
of the ceiling height (0.1 H), spacing shall be in accordance
with 17.7.3.2.4.2(2).