Obstruction Criteria
Figure 27
Additional sprinklers not required due to obstruction 6” (150 mm) or less
in height with a minimum 3-1/2” (90 mm) gap provided between the top of
the obstruction and the roof deck
Additional sprinklers required beyond obstruction greater than 6” (150
mm) in height or where a minimum 3-1/2” (90 mm) gap is not provided
between the top of the obstruction and the roof deck.
Additional sprinklers not required due to obstruction 6” (150 mm) or
less in height with a minimum 3-1/2” (90 mm) gap provided between
the top of the obstruction and the roof deck.
Additional sprinklers required beyond obstruction greater than 6” (150
mm) in height or where a minimum 3-1/2” (90 mm) gap is not provided
between the top of the obstruction and the roof deck.
Additional sprinklers not required below horizontal obstruction 4’-0”
(1.2 m) or less in width.
Additional sprinklers required below horizontal obstruction greater than
4’-0” (1.2 m) in width.
Additional sprinklers not required beyond horizontal obstruction more than
6” from bottom of rafter
Additional sprinkler required beyond horizontal obstruction less than 6”
(150 mm) from bottom of rafter.
Additional sprinkler not required beyond
vertical obstruction (see figure at left) where:
Obstruction width, W
Minimum distance between
sprinkler and obstruction, D
1” or less (25 mm or less)
6” (150 mm)
1” to 4” (25 to 100 mm)
1’-0” (300 mm)
4” to 8” (100 to 200 mm)
2’-0” (600 mm)
8” to 10” (200 to 250 mm)
5’-0” (1.5 m)
10” to 20” (250 to 500 mm)
10’-0” (3.0 m)
20” to 30” (500 to 750 mm)
15’-0” (4.5 m)
30” to 40” (750 to 1000 mm)
20’-0” (6.0 m)
40” to 48” (1000 to 1200 mm)
25’-0” (7.5 m)
Provide sprinklers beyond vertical obstructions
not meeting the criteria above.
Bulletin 056
February 2020
Page 22 of 27
www.reliablesprinkler.com
