NFPA Journal - May/June 2019 - 43

CODES, STANDARDS
AND COMPLIANCE

NFPA 13

Water-based fire
protection systems

Conditions for
omitting sprinklers
above cloud ceilings
By Jacqueline Wilmot
ecently, the department

R

responsible for providing answers to technical
questions on NFPA 13,
Installation of Sprinkler
Systems, received some inquiries
regarding the sprinkler requirements
for cloud ceilings.
Although this subject was newly
addressed beginning with the 2016
edition of NFPA 13, many jurisdictions
have not yet adopted the most recent
editions of the standard. Even so, it is
important to be aware of the fact that
the most recent edition of the standard
reflects the technical committee's latest
intent on the subject. That means that
even if your jurisdiction hasn't adopted
the latest and greatest, and the situation you are dealing with is addressed
in a more recent edition, be sure to
discuss options with your authority
having jurisdiction (AHJ).
The first question many have is
whether NFPA 13 defines "cloud ceilings."
If referencing the 2016 edition or later,
the answer is yes. Cloud ceilings are
now defined as "any ceiling system, not
including sloped ceilings, installed in the
same plane with horizontal openings to
the structure above on all sides." Cloud
ceilings are now addressed in Subsection
9.2.7 of the 2019 edition, which provides
the specific installation requirements for
cloud ceiling applications.
The key takeaway from this section
is that sprinklers can be omitted above
cloud ceilings where four conditions
are met.
First, the combined total area of the
openings around the cloud are less

than or equal to 20 percent of the area
of the ceiling, construction feature, or
plane used to determine the boundaries of the compartment. The intent of
this provision is to ensure the openings
along a wall or between clouds are not
too large. Fire modeling has shown that
when the openings are too large, heat
will collect above the cloud ceiling. The
sprinklers installed on the lower ceiling should activate when the opening
dimension is no greater than 1 inch per
foot of elevation above the floor. When
the opening is too large, the space
above the ceiling should not be considered a concealed space.
Second, the cloud width, the opening gap width between clouds, and the
maximum sprinkler protection area
are all in accordance with Table 9.2.7.1.
The main concept to understand here
is that for every vertical foot between
the floor and the cloud ceiling panel,
there is one inch of separation allowed
between cloud ceilings without having
to install sprinklers above the cloud
(in the structural ceiling). In other
words, if you have a distance of 10 feet
between the floor and the bottom of the
cloud ceiling, and the distance between
cloud ceilings (or the cloud and the
wall) is 10 inches or less, sprinklers can
be omitted above the cloud. The associated annex language provides a simple
equation to determine the appropriate
column to use in Table 9.2.7.1.
Third, the requirements of 9.2.7.2
must be met. Those include:
» All sprinklers need to be quickresponse 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 10.2.4.2(a), or ordinary hazard
occupancies as provided in Table
10.2.4.2.1(b).
» Where extended coverage sprinklers
are used, the maximum distance
between sprinklers cannot exceed 16
feet.
N F PA . O R G / J O U R N A L * NFPA JOURNAL

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