exposed wood in a soffit

[FM William Burns]

I may be way out in left field but I believe that if the drywall was wraped horizontal to vertical the combustible space would meet the exception for 160 cubic ft. found in 8.15. I'm in the "don't sing it but bring it" camp and want to see where the FM is hanging his/her hat on this one based on the drawing I'm looking at.

 

[cda]

I may be way out in left field but I believe that if the drywall was wraped horizontal to vertical the combustible space would meet the exception for 160 cubic ft. found in 8.15. I'm in the "don't sing it but bring it" camp and want to see where the FM is hanging his/her hat on this one based on the drawing I'm looking at.

You might not be seeing the entire cow.

Op said this happens in various areas, so hard to tell how big the void is

Suggested sprinkler company look at it and advise if anything in 13 applies

 

[ICE]

Another thing I wonder about is the sprinkler heads, don't they need to be accessible for inspection and service?

Can a fire guy answer that please? The heads in this case would be buried.

Thanks

 

[IJHumberson]

Can a fire guy answer that please? The heads in this case would be buried.Thanks

There isn't any requirement in NFPA 13 to provide access to sprinklers in concealed spaces - when you have entire floor/ceiling assemblies with sprinkler protection in the interstitial space, it really is impractical to provide enough openings to be able to inspect all the sprinklers inside the floor/ceiling assembly.

I agree with FM Burns (as usual), the simplest solution would be to provide draftstopping to limit the volume of the concealed spaces to less than 160 ft3. Short of that, if the picture shown is what the Fire Marshal is asking for, I'm saying "WHY?!" - and "HOW?!" I don't see a need for the dryall on the 'inside' edges of the framing members forming the soffit (or how you could do that) - to drwyall the side exposed to the ACT ceiling side would create a limited combustible space above the ACT ceiling and, therefore, would be compliant without sprinkler protection. And the sprinkler in the soffit provides the required protection for that concealed space, without the drywall... IF there was a way to build it the way the drawing shows, then it isn't a concealed combustible space and sprinkler protection would not be required.