Sprinklers above a suspended ceiling when ceiling does not cover room?

[carlosgw]

Out of control architect: An open office space with partial suspended ceiling (or very large ceiling clouds). One space has a suspended ceiling for about 80% with three areas open to the deck above. The other has maybe 70% ceiling at different levels (picture a rectangle with a 9’ ceiling in the middle covering say 50%, 3’ open, then a rectangle ring 4’ wide at 8’, then maybe 3’ open around the outside.
The space above the ceiling is all non-combustible.
Do we need to treat it as open space with sprinklers at the deck and also in the ceiling (treat the ceilings like clouds)?

 

[MatthewJWillis]

Yes and Yes.

You sprinkler the roof as if exposed. The clouds then fall under the greater than 4'-0" rule.

When it gets fun is when there is only 6" between the clouds. Same rules apply.

R/
Matt

 

[TravisMack]

Yeah...people tend to over complicate this. It is as simple as Matt stated.

1st, start with the premise that all areas of a building must be provided with sprinkler protection. Then, you can go to the exemptions that allow sprinklers to be omitted. One of these is non-combustible concealed spaces. Because your ceilings aren't 100% coverage of the room, the space above the ceiling is no longer concealed.

Again, as Matt said, these fall under the 4' rule to require sprinklers under them.

Travis Mack
MFP Design, LLC

http://www.mfpdesign.com

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[MatthewJWillis]

The past 2 years have seen some fairly extensive testing and modeling on this very subject. The results are going to be presented at the summer 2015 NFPA meeting.
The testing report is available @ NFPA.org. A simple search of "Ceiling Clouds and Fire Sprinklers" will get you there.
In a nutshell, there are some allowances that will be investigated to allow omission of the sprinklers above the cloud.
As of now though, they are obstructions plain and simple.

R/
Matt

 

[carlosgw]

OK a third location:
A 100' X 100' area with ceiling. There is a 34' X 28' opening (not exactly in the middle of the space)with a 26' X 20' cloud in the middle of the opening. Do I sprinkler the entire space above the ceiling? Even say 35' away from the opening?

Common sense is breaking down.

 

[MatthewJWillis]

As of right now the way I understand it...
If you can see above it, then it is Not concealed.
This was also a consideration when you could look from the stockroom of a store, and see above the ceiling over the shopping aisles.


I would think however, using the report, you maybe could ask for a variance from your approving authority. Maybe spacing sprinklers around the opening to keep the ceiling cool where heat may gather.
There are instances in 13 of this being done around isolated combustible concealed in section 8.15. The report helps identify the actions of the heat/fire.
Interestingly enough, the fire plume skews due to the effects of the cloud.
Also, if you were to build a non-combustible "box" around the large opening, out of sight, then maybe that could be considered as "Non-Combustible Concealed Space".

The entire trick is to ensure the sprinkler is located in the heat.

R/
Matt

 

[TravisMack]

Carlos:

Matt is dead on. As of today, you sprinkle that entire space above. I have done jobs where the architect wanted the exposed industrial look in a corridor so they didn't put a ceiling in that area. It opened to about 75' of office in each direction. We were required to put sprinklers at the deck level throughout the entire floor. The architect would not budge on running the corridor walls to the deck so the rest of the area was concealed.

Travis Mack
MFP Design, LLC

http://www.mfpdesign.com

"Follow" us at

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[Woodrow57]

Typically there is also a requirement from the building and fire codes to provide fire sprinklers above the finished area, when they are not fully demised. They look at it from a different perspective, sprinkler contractors often say we are protecting the floor area but if the area above the ceiling is not fully demised from the finished area below (an example is a warehouse with a finished office space along a wall) then you must protect the area above the ceiling as well as the finished space below the ceiling. A cloud is similar, if it is not demised the "open plenum" space above the cloud must be sprinklered too. I don't recall what edition the verbiage was inserted into the building code, but two topics that were related were fires flashing up into the ceiling plenum due to open areas of the ceiling and the warehouse side protection came about as people were storing cardboard and other items on their lay-in ceilings and fire marshals were tired of telling owners / tenants off when they said it was not a code requirement to demise the space.

BTW- a solution is to run a vertical soffit from the cloud to the deck and paint it black. I know just what the other designer is talking about though, I did an office area in a 42' clear warehouse, they put in three levels of slanted clouds, none of them intersected each other but 90% of the floor area was obstructed from protection at the roof deck level. We installed hard pipe drops, some went through a higher cloud to get to a lower cloud, and in the end all the clouds had fire sprinkler protection below them.

 

[cdafd]

Woodrow

You might look at 8.15.22 nfpa 13 2010 edition

 

[NightME]

Why don't you look at 8.15.23.3 (and the diagram in the Annex) of the 2013 Edition, there are times when the entire roof level doesn't need sprinklered. I'm sure its similar in the 10 and maybe even the 07...just don't have time to search through all 3 editions.

 

[MatthewJWillis]

It was added in 10 as 8.15.22.3


It allows you to limit the entire system above. But there are stipulations...


8.15.22.3* Where there is a noncombustible space above a
noncombustible or limited-combustible drop ceiling that is
sprinklered because it is open to an adjacent sprinklered
space on only one side and where there is no possibility for
storage above the drop ceiling, the sprinkler system shall be
permitted to extend only as far into the space as 0.6 times the
square root of the design area of the sprinkler system in the
adjacent space.


R/
Matt

 

[TravisMack]

The key with Matt's reference is that it is only open on one side. I've seen several guys try to apply this a room with an exposed ceiling, that leads over into the rooms above it on 2-4 sides.

The picture in the Annex clearly indicates the intent of that referenced section.

Travis Mack
MFP Design, LLC

http://www.mfpdesign.com

"Follow" us at

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[Woodrow57]

Per the referenced verbiage from the NFPA standard, where there is NO possibility for storage. I have seen all kinds of things stored on lay-in ceiling grids/ACT, and even more and worse above hard ceilings. NFPA standards are based on anticipation of a fully sprinklered building (fully meaning areas that are required to be sprinklered) and if the space above a ceiling is not demised, sprinklering above and below may be required. Similar to an open mezzanine, conveyor, grated walkway...

PW located in the heart of America-
Fire sprinkler contracting since 1978
NICET and ICC certified

 

[MatthewJWillis]

I agree Woodrow.

If an owner finds a convenient cubby hole, it will be used. But we as contractors must follow the minimum unless we are brought in at the concept stage. (My what an interesting Unicorn...)


R/
Matt

 

[sfallows]

matt i think the chance of a variance has to do with not only the report but the comfort level of the fire official with their knowledge of fire protection.

 

[MatthewJWillis]

Correct.

Perhaps we should start with the question, " Are you a member of the Eng-Tip Tech Forum?"
If the answer is no, move on...

R/
Matt