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Rated Acoustical Ceiling

T

tmurray

SAWHORSE
Joined
Jun 10, 2011
Messages
3,398
Location
NB, Canada
I have an existing building that a developer wants to change the occupancy on. The owner is stating that the ceiling tiles are rated for 1 hour. There are no clips to keep them in place, but the T would support their use. My question is; are the ceiling tiles usually stamped with identifying marks on the back to indicate their rating. I seem to remember seeing it once.
 
usually there is a manufacturer # that you can look up on the back of the tile. or stamped fireguard possibly depending on the manufacturer. clips not necessarily required.
 
cda said:
Why the one hour though ??
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NBCC 2010: 3.2.2.25.(2)(a): floor assemblies shall be fire separations and, if of combustible construction, shall have a fire-resistance rating not less than 45 min,

The floor system is open web wood joists. As to why they went with a 1 hour over 45 minutes I cannot say.
 
I think I would require documentation of the entire ceiling system to evaluate it. The grid also has to be listed for one hour assembly.

Than is the system listed for the use!!!! I am thinking no.
 
The concept is "floor/ceiling" assembly; essentially "skin to skin" from top to bottom or vise versa. If the assembly has a "rated" suspended ceiling then all components of construction must be in accord with the listing. UL (USA) listings normally have more than one manufacturer for components otherwise the listing is "proprietary" for that individual manufacturer and system. Right now I don't know of any current listed suspended ceilings that form a fire rated component by themselves or are the main component in a fire rated floor/ceiling assembly. Older listings used to have them and the ones without clips usually had heavy tiles, most of them gypsum core based materials.

IMHO suspended grid fire rated assemblies are not desirable due to user or maintenance ignorance that effectively causes breaches in the system by not re-installing required clips or using standard ceiling tiles in lieu of the fire resistant tiles.
 
The tiles, the grid, AND the suspending wire all must be per listing to qualify for the rating.

UL has listed floor ceiling assemblies that incorporate suspended ceilings.

Desirable or not, a listed assembly meets Code.
 
steveray said:
I don't know that a rated "drop ceiling" meets the intent of "floor assembly" being noncombustible or fire rated.....
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The intent of the code is to protect the combustible floor system from fire from the floor below, so in this case it does meet the intent of the code.
 
Ok so if you just need a barrier sounds like this would work.

Still would get documentation that the entire assembly is listed as an assembly.

To include documentation on the tiles,

So you can have them pull a per centage of the tiles you point out to check.
 
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