sprinklernotes
Cloud Ceilings
You have asked the following question: “There is a new Table for determining
the Maximum Sprinkler Protection area based on the width of both the Ceiling
Clouds and openings between the clouds (Table 8.15.24.1). The formula provided
within this table is hard to interpret. Math formulas are not our challenge,
just interpreting what the formula actually is from the narrative is
confusing.” In response to your question, we have reviewed NFPA 13, 2016
edition as the applicable standard. Our informal interpretation is the Table is
applied as follows.
This is a really confusing issue partly because all of the criteria is new for
the 2016 edition of NFPA 13. To start off, note there are other requirements on
this issue in other sections. Per the definition of cloud ceilings in Section
3.3.5.4 this section cannot be applied if the clouds are tilted. Another remote
requirement is in Section 8.15.1.2.1.2 where the openings cannot exceed 20
percent of the total area of the ceiling and where the length is greater than 4
ft you cannot have a depth greater than 8 in. The good news is the limitation
on the length and depth have been removed for the 2019 edition. Also keep in
mind Section 8.15.24.2.2 limits the ceiling height to 20 ft.
The intent of Section 8.15.24 is to give us a sprinkler spacing based up the
ceiling height and the gaps or spaces between the cloud ceiling panels. Table
8.15.24.1 gives us four items we have to consider. The first item is the
minimum width or least dimension of the cloud ceiling. For example, if the
cloud ceilings were 4 ft. by 8 ft. we would have to choose the 2.5 ft-4 ft
line. The second through fourth columns allow us to determine our area of
coverage based on the ceiling height and opening width or gaps between ceiling
panels. The bigger the gap, the lower the area of coverage. Only one of the
columns will apply depending on your circumstances. For example, take a ceiling
located at 12 ft. with 4 ft. by 8 ft. ceiling clouds. The second column tells
us we can have a maximum of 0.5 in. of space between panels for every foot of
the ceiling height. With a 12-ft. ceiling the clouds need a 6 in. or less gap
between the clouds (12 ft. x 0.5 in. = 6 in.) in order to apply the 225 sf area
of coverage. If the gap is bigger than 6 inches, we move to the next column.
This column states a maximum of 0.75 in. of space between panels for every foot
of ceiling height, allowing a gap up to 9 in. (12 ft. x 0.75 in. = 9 in.). With
a 9-in. gap, the maximum sprinkler spacing would then be 120 sf. If the gap is
bigger than 9 in. we refer to the final column. The final column states we can
have a maximum 1 in. of space between panels for every foot of ceiling height,
allowing a gap up to 12-in. (12 ft. x 1.0 in. = 12 in.), with a 12-in. gap the
maximum sprinkler spacing would then be 70 sf. If the gap is larger than 12 in.
(for a 12 ft. ceiling height) then sprinkler protection would be required above
the cloud ceiling.
Cloud Ceilings
You have asked the following question: ÒThere is a new Table for determining
the Maximum Sprinkler Protection area based on the width of both the Ceiling
Clouds and openings between the clouds (Table 8.15.24.1). The formula provided
within this table is hard to interpret. Math formulas are not our challenge,
just interpreting what the formula actually is from the narrative is
confusing.Ó In response to your question, we have reviewed NFPA 13, 2016
edition as the applicable standard. Our informal interpretation is the Table is
applied as follows.
This is a really confusing issue partly because all of the criteria is new for
the 2016 edition of NFPA 13. To start off, note there are other requirements on
this issue in other sections. Per the definition of cloud ceilings in Section
3.3.5.4 this section cannot be applied if the clouds are tilted. Another remote
requirement is in Section 8.15.1.2.1.2 where the openings cannot exceed 20
percent of the total area of the ceiling and where the length is greater than 4
ft you cannot have a depth greater than 8 in. The good news is the limitation
on the length and depth have been removed for the 2019 edition. Also keep in
mind Section 8.15.24.2.2 limits the ceiling height to 20 ft.
The intent of Section 8.15.24 is to give us a sprinkler spacing based up the
ceiling height and the gaps or spaces between the cloud ceiling panels. Table
8.15.24.1 gives us four items we have to consider. The first item is the
minimum width or least dimension of the cloud ceiling. For example, if the
cloud ceilings were 4 ft. by 8 ft. we would have to choose the 2.5 ft-4 ft
line. The second through fourth columns allow us to determine our area of
coverage based on the ceiling height and opening width or gaps between ceiling
panels. The bigger the gap, the lower the area of coverage. Only one of the
columns will apply depending on your circumstances. For example, take a ceiling
located at 12 ft. with 4 ft. by 8 ft. ceiling clouds. The second column tells
us we can have a maximum of 0.5 in. of space between panels for every foot of
the ceiling height. With a 12-ft. ceiling the clouds need a 6 in. or less gap
between the clouds (12 ft. x 0.5 in. = 6 in.) in order to apply the 225 sf area
of coverage. If the gap is bigger than 6 inches, we move to the next column.
This column states a maximum of 0.75 in. of space between panels for every foot
of ceiling height, allowing a gap up to 9 in. (12 ft. x 0.75 in. = 9 in.). With
a 9-in. gap, the maximum sprinkler spacing would then be 120 sf. If the gap is
bigger than 9 in. we refer to the final column. The final column states we can
have a maximum 1 in. of space between panels for every foot of ceiling height,
allowing a gap up to 12-in. (12 ft. x 1.0 in. = 12 in.), with a 12-in. gap the
maximum sprinkler spacing would then be 70 sf. If the gap is larger than 12 in.
(for a 12 ft. ceiling height) then sprinkler protection would be required above
the cloud ceiling.
