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Concealed spaces/attic spaces in combustible construction.

M

mwskopf

SAWHORSE
Joined
Sep 30, 2019
Messages
45
Location
Kansas
Morning all,
I have a client that wants to do a remodel inside of an existing type V building.
The construction type is VB with wood bearing walls and Pitched (4:12 or so) wood roof trusses with suspended ceiling below. (big rectangle)
building is 5,800 s.f. and is an A-2 worship space with a couple classrooms and new bathrooms.
No fire Sprinklers
Code is IBC 2018.
My question deals with the wood trusses above the suspended ceiling. Am I right in assuming that the combustible attic trusses are acceptable as is as long as the attic is properly draftstopped per 718.4? (3,000s.f.)
Thanks
 
Type V-B, no issue.

Is there a change of use, alteration, addition, etc. going on? What is bringing the question to mind?
 
No change of use or addition -only remodel with some space reconfig. I ask the question because the owner and I discussed (Very early stages of process) installing a nicer lay-in ceiling, or some drywall clouds with open grid etc... If we did do something like, that, I would want to do the draft stopping.
 
718.4 Draftstopping in attics.
Draftstopping shall be installed to subdivide attic spaces where required by Section708.4.2. In other than Group R, draft stopping shall be installed to subdivide combustible attic spaces and combustible concealed roof spaces such that any horizontal area does not exceed 3,000 square feet (279 m2). Ventilation of concealed roof spaces shall be maintained in accordance with Section 1202.2.1.

Seems to me that this has been code for a long time. I don't know what the code was when your building went up and I don't know what code applies in Kansas today. I do know that the code is a bare minimum and a draft stop in your case would not be all that costly.
 
Agreed. I am not sure what code it was built under (If any) this is a small little town.
Let me switch gears a bit.
Lets say this were a new build. There is no need fire separate the attic space in a V-B because of the ratings indicated for building elements on table 601 correct? if the building were V-A then the ceiling dividing the attic from the occupied space would need to be 1hr with fire dampers in hvac penetrations etc. It is a good chance that I am overthinking this.
 
Thanks all, I think I was getting caught up in rated vs non-rated as ICE commented (second part of post). For some reason I was thinking the attic trusses needed to be separated in a V-B.
 
"building is 5,800 s.f. and is an A-2 worship space with a couple classrooms and new bathrooms."

Worship space would be A-3.
 
mwskopf said:
Agreed. I am not sure what code it was built under (If any) this is a small little town.
Let me switch gears a bit.
Lets say this were a new build. There is no need fire separate the attic space in a V-B because of the ratings indicated for building elements on table 601 correct? if the building were V-A then the ceiling dividing the attic from the occupied space would need to be 1hr with fire dampers in hvac penetrations etc. It is a good chance that I am overthinking this.
Click to expand...
I had a similar question about ceilings in 1 hour construction, but looking at Table 601, I don't see any requirements for ceilings....only floors, roofs and bearing walls.
 
mwskopf said:
No change of use or addition -only remodel with some space reconfig. I ask the question because the owner and I discussed (Very early stages of process) installing a nicer lay-in ceiling, or some drywall clouds with open grid etc...
Click to expand...
How is the attic insulated? In the past it was common practice to lay the insulation directly on the suspended ceiling. Today that is no longer permissible. You might want to research that with your local AHJ if you are considering doing anything with the ceiling.
 
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