spinklers above a wood slat ceiling
spinklers above a wood slat ceiling
(OP)
Hello, I have a question relating to fire sprinkler systems above a wood slat ceiling where the space above is a open plenum return. The space is about 5,500 SF and in a type 5, 1-hour rated construction type. The wood trusses have two layers of gyp board on the bottom chord of the truss but that is the only combustible material in the plenum space. Not all of the walls go to deck so conceivably hot air can move around in this open area above the ceiling. In my mind if we have locations where there are wood slat ceilings (Armstrong, class A rated) we have upturned and downturned heads then there should be coverage. The whole plenum space does not need to have sprinklers in it to meet code. The fire department is saying that if there is an open plenum, and not all of the walls go to deck, then if there is a fire that starts in this space heat will dissipate and won't activate the upturned heads above the wood slat ceilings. I am not seeing anywhere in the code that states this is a requirement. Again there are two layers of gyp board on the bottom chords of the wood trusses and there is no wood in the plenum and the walls are made with metal studs. The only wood in the ceiling is where the wood slats are. He is talking about putting a gyp board lid above the wood slat ceilings to contain the heat so that the upturned heads activate. Any help in understanding the sprinkler requirements above a wood slat ceiling with an open air plenum (possibly non-combustible) would be appreciated.
Thanks,
Jim
Thanks,
Jim





RE: spinklers above a wood slat ceiling
Travis Mack
MFP Design, LLC
www.mfpdesign.com
"Follow" us at https://www.facebook.com/pages/MFP-Design-LLC/9221...
RE: spinklers above a wood slat ceiling
RE: spinklers above a wood slat ceiling
Now, I would believe that your plenum space is non-combustible from your description.
For the slatted area, you put sprinklers at the gyp ceiling (bottom of trusses). Then, if the wood slat ceiling is such that it creates an obstruction, then put sprinklers below that ceiling as well. I can't see why a gyp lid would matter. The slats may or may not be far enough apart so that they don't even constitute an obstruction and sprinklers at the hard ceiling are adequate.
Travis Mack
MFP Design, LLC
www.mfpdesign.com
"Follow" us at https://www.facebook.com/pages/MFP-Design-LLC/9221...
RE: spinklers above a wood slat ceiling
Are you the building designer and not fire sprinkler company??
RE: spinklers above a wood slat ceiling
Is there any opeing between the slats??
Something Like this where there are no openings:::
http://www.screenwood.com.au/images/pageheroes/app...
Or this::
http://www.martinintegrated.com/img/wood/UCI-Busin...
RE: spinklers above a wood slat ceiling
Another line of reasoning that I've heard is that if you have a gyp board lid above a wood slat ceiling then it is no longer exposed to the open plenum and no upturned heads are required. This seems like fuzzy logic to me that I don't understand and again I can find no reference in the code that allows this exception.
RE: spinklers above a wood slat ceiling
Travis Mack
MFP Design, LLC
www.mfpdesign.com
"Follow" us at https://www.facebook.com/pages/MFP-Design-LLC/9221...
RE: spinklers above a wood slat ceiling
So you are meeting NFPA 13
Now if they have a fire protection engineer on the ahj staff, that says otherwise?? Well would ask for some documentation.
Do you have a fire sprinkler company advising you.
If so have them show you the open grid ceiling exception, which you do not meet. But may help with your argument
RE: spinklers above a wood slat ceiling
RE: spinklers above a wood slat ceiling
RE: spinklers above a wood slat ceiling
*****. Do you have a fire sprinkler company advising you????
RE: spinklers above a wood slat ceiling
Might with a strech meet cloud ceiling:
3.3.5.1 Cloud Ceiling. Any ceiling system installed in the same plane with horizontal openings to the structure above on all sides. This does not include sloped ceilings as defined in 3.3.5.4.
If so look at 8.15.24:
8.15.24 Cloud Ceilings.
8.15.24.1* Sprinklers shall be permitted to be omitted above cloud ceilings where both of the following apply:
(1)*
The openings around the cloud and the maximum sprinkler protection area meet the requirements of 8.15.1.2.1.2 and Table 8.15.24.1
(2)
The requirements of 8.15.24.2 are met.
Table 8.15.24.1 ::::: table does not copy
Maximum Sprinkler Protection Area Based on Ceiling Cloud Width and Opening Width
8.15.24.2 When sprinklers are omitted from above a cloud ceiling in accordance with 8.15.24.1, the requirements of this section shall apply.
8.15.24.2.1 All sprinklers shall be quick response standard spray or extended coverage pendent or upright sprinklers.
Plus look at:
8.15.1.2.1.1 The space shall be considered a concealed space even with small openings such as those used as return air for a plenum.
8.15.1.2.1.2 Small openings with a combined total area of not more than 20 percent of the ceiling, construction feature, or plane used to determine the boundaries of the concealed space shall be permitted where length greater than 4 ft (1.2 m) shall not have a width greater than 8 in. (200 mm).
8.15.1.2.1.3 The space above cloud ceilings meeting the requirements in 8.15.24.1 and having openings with a combined total area of not more than 20 percent of the ceiling, construction feature, or plane used to determine the boundaries of the concealed space shall be permitted.