"Combustible" concealed space?
"Combustible" concealed space?
(OP)
I have a two story bank building.
The first two floors are non-combustible construction with metal studs, masonry and drywall.
The attic is wood truss and will need to have a dry system protecting the space.
The architectural drawings shows batt insulation between the bottom chords of the truss. It appears the bottom of the wood trusses will be exposed.
Here's a screen capture.
h ttp://img2 11.imagesh ack.us/img 211/3182/c oncealedsp acell8.jpg
My question is will the space between the bottom of the wood truss and second floor suspended ceiling need sprinklers?
From NFPA #13 - 2002
8.14.1.2.13 Concealed spaces below insulation that is laid directly on top of or within the ceiling joists in an otherwise sprinklered attic shall not require sprinkler protection.
I think this applies, the space doesn't need sprinklers but I would feel better with confirmation.
Thanks
The first two floors are non-combustible construction with metal studs, masonry and drywall.
The attic is wood truss and will need to have a dry system protecting the space.
The architectural drawings shows batt insulation between the bottom chords of the truss. It appears the bottom of the wood trusses will be exposed.
Here's a screen capture.
h
My question is will the space between the bottom of the wood truss and second floor suspended ceiling need sprinklers?
From NFPA #13 - 2002
8.14.1.2.13 Concealed spaces below insulation that is laid directly on top of or within the ceiling joists in an otherwise sprinklered attic shall not require sprinkler protection.
I think this applies, the space doesn't need sprinklers but I would feel better with confirmation.
Thanks





RE: "Combustible" concealed space?
if it looks like wood it burns like wood.
can they sheet rock it to cover it?? verses the sprinklers??
RE: "Combustible" concealed space?
You have sprinklers at the ceiling and in the space above the insulation.
So, 1 for and 1 against...let's see how it tallies up..
Travis Mack
MFP Design, LLC
RE: "Combustible" concealed space?
RE: "Combustible" concealed space?
believe the section quoted does not address what the picture shows.
WHAT IF, oh no, the fire starts above the drop ceiling and below the exposed bottomof the wood truss,
1. the attic sprinklers are ot going to do any good till the roof burns off.
2. the sprinlers below the drop ceiling are not going to do any good till the building burns down
to me if you pop a ceiling tile and see wood and there is no 8.14.1.2 section that does not require sprinklers you sprinkle it.
RE: "Combustible" concealed space?
RE: "Combustible" concealed space?
Yes, drawings show anywhere from 2' to 4' void space but there are two considerations which lead me to think sprinklers were not required.
There section 8.14.1.2.13 I quoted. Accoding to this even if the construction below the insulation was combustible, say wood studs were used instead of metal studs, sprinklers still wouldn't be required.
Consider as well non-combustible or "limited combustible" spaces.
8.14.1.2* Concealed Spaces Not Requiring Sprinkler Protection.
8.14.1.2.1 Noncombustible and limited combustible concealed spaces with no combustible loading having no access shall not require sprinkler protection. The space shall be considered a concealed space even with small openings such as those used as return air for a plenum.
I don't feel I am qualified to determine what is "limited combustible" so I don't. That being said I do know just because you see wood doesn't necessarily mean it has to be sprinklered. When I have a project where there limited is a question I have it reviewed by a FPE because that's their job.
RE: "Combustible" concealed space?
nfpa #13 2007: 8.15.1.2.13 Concealed spaces below insulation that is laid directly on top of or within wood joists or composite wood joists used as ceiling joists in an otherwise sprinklered concealed space, with the ceiling attached directly to the bottom of the joists, shall not require sprinkler protection.
I think the earlier intention prior to 2007 was that batt insulation laid on top of the bottom chord of truss (or joist) sometime had pockets due to the insulation actually being tented over piping, light fixtures etc... and was referring to no added protection in this case.
RE: "Combustible" concealed space?
3.3.14 Limited-Combustible Material. A building construction material that does not comply with the definition of noncombustible material that, in the form in which it is used, has a potential heat value not exceeding 3500 Btu per lb (8141 kJ/kg) (see NFPA 359, Standard Test Method for Potential Heat of Building Materials), and that complies with either of the following, (a) or (b). Materials subject to increase in combustibility or flame spread rating beyond the limits herein established through the effects of age, moisture, or other atmospheric condition shall be considered combustible. (a) Materials having a structural base of noncombustible material, with a surfacing not exceeding a thickness of in. (3.2 mm) that has a flame spread rating not greater than 50. (b) Materials, in the form and thickness used, other than as described in (a), having neither a flame spread rating greater than 25 nor evidence of continued progressive combustion and of such composition that surfaces that would be exposed by cutting through the material on any plane would have neither a flame spread rating greater than 25 nor evidence of continued progressive combustion.
would say 8.14.1.2.13 would apply if there was some non com attached to the bottom of the wood truss.
if you read the section to me it is saying that the attic sprinklers would wet the wood/ insulation,
but do not see that happening if the fire starts in the void area above the drop ceiling.
once again if there was another section that applies would not require them.
also would look to see if there is an ignition source in the void space.
I know I have gotten my hand slapped for saying that before. slap away.
RE: "Combustible" concealed space?
RE: "Combustible" concealed space?
RE: "Combustible" concealed space?
I meant shall be permitted to be ommitted - as in no sprinklers required:)."
I don't have a copy of 2007 yet having put it off since we're still operating on the 2002 edition.
Can someone copy and paste NFPA 13, 2007 section 8.15.1.2.16, A.8.15.1.2.16 and figure A.8.15.1.2.16? Well, not the figure.
RE: "Combustible" concealed space?
A.8.15.1.3 See figure A.8.15.1.2.16
Picture is a bit blurry but should help.
RE: "Combustible" concealed space?
The description under it says 'Figure A.8.15.1.2.16 One acceptable arrangement of a concealed space in a truss construction not requiring sprinklers.
To the left under the insulation it says 'Concealed space below truss bottom chords.'
RE: "Combustible" concealed space?
That appears to be exactly the situation I am dealing with.
I am going to order the handbook tomorrow.
Thanks.
RE: "Combustible" concealed space?
RE: "Combustible" concealed space?
not sure if your set up meets ALL requirements of this section