# Interior partitions and how they affect a floor/clg assembly (continuous drywall?)



## error404 (Nov 21, 2013)

New Condo units... Type 5-B Construction - 2009 NFPA

Let's say we are specifying UL#- L528 Floor/CLG assembly (Wood trusses / resilient channels/ 5/8" Drywall).

Normal construction practice is to frame the interior walls before installing the drywall. Which means that the 5/8" Drywall at the ceiling would not be continuous were it meets the interior partitions walls. Our fire marshal wants an UL# that shows that providing a continuous blocking above the interior partitions (to allow for the drywall ceiling to be nailed) is an approved/tested method.

Anyway, I'm having a hard time finding that connection/detail on the UL book.

I already placed a call on UL-help and they are going to get back to me... but wanted to see if anyone else has run into a similar experience.

Thanks


----------



## mark handler (Nov 21, 2013)

Talk to your truss manufacturer

Many have stock details


----------



## steveray (Nov 21, 2013)

If the interior partions are also fire partitions you might be able to use.......

708.4 Continuity.

Fire partitions shall extend from the top of the floor assembly below to the underside of the floor or roof slab or deck above or to the fire-resistance-rated floor/ceiling or roof/ceiling assembly above, and shall be securely attached thereto. If the partitions are not continuous to the deck, and where constructed of combustible construction, the space between the ceiling and the deck above shall be fireblocked or draftstopped in accordance with Sections 717.2.1 and 717.3.1 at the partition line.

Or hold the walls down 5/8" and slip the drywall in......or put 3.5"drywall pieces on top of the plates.....Or......


----------



## mtlogcabin (Nov 21, 2013)

> Our fire marshal wants an UL# that shows that providing a continuous blocking above the interior partitions (to allow for the drywall ceiling to be nailed) is an approved/tested method.


Since when does the fire marshal enforce the building code? Ask him for a code section.

I believe a double top plate of 3 inches thick will provide the 30 minutes that is required.

712.3 Fire-resistance rating.

The fire-resistance rating of floor and roof assemblies shall not be less than that required by the building type of construction. Where the floor assembly separates mixed occupancies, the assembly shall have a fire-resistance rating of not less than that required by Section 508.4 based on the occupancies being separated. Where the floor assembly separates a single occupancy into different fire areas , the assembly shall have a fire-resistance rating of not less than that required by Section 707.3.9. Horizontal assemblies separating dwelling units in the same building and horizontal assemblies separating sleeping units in the same building shall be a minimum of 1-hour fire-resistance-rated construction.

Exception: Dwelling unit and sleeping unit separations in buildings of Type IIB, IIIB and VB construction shall have fire-resistance ratings of not less than 1/2 hour in buildings equipped throughout with an automatic sprinkler system in accordance with Section 903.3.1.1.


----------



## RJJ (Nov 21, 2013)

What state are you in? Why 2009 NFPA? Ask for chapter and verse of the FM.


----------



## JBI (Nov 22, 2013)

I agree that a code citation would be appropriate. I also agree there is probably a reasonable solution... install the gypsum board to the ceilings at the partition lines before building the partition wall framing?


----------



## RLGA (Nov 25, 2013)

If floor joists are bearing on the walls, then the placement of gypsum board between the joists and double top plates of walls would not be permitted (2012 IBC Section 2308.8.1).


----------



## Builder Bob (Nov 25, 2013)

Once upon a time their used to be a hierarchy of what walls were to be built when. This usually had the fire rated assemblies constructed first- fire walls, fire barriers, fire partitions (complete with sheet rock) then had the non-load bearing partitions built.

this usually allowed stair shafts to be built and completed before the other non-load bearing walls were built to allow continuation of fire barriers.

this is old school but seems to eliminate the concern about the intersection of a wall partition in a fire rated roof/ceiling assembly.


----------



## Frank (Nov 26, 2013)

Wood is about 20 minutes to the inch so three inch top plate provides the hour protection that the 5/8 type x and resilient chanels do.


----------

