Laundry Chute, Shaft Walls, and intersecting with floors

[lunatick]

Question relates to application of Section 707 Shafts as is affected by Section 706.5 continuity of firebarriers.

Issue is a Laundry Chute, and the detail for the chute support.

The shop indicates the supports to be attached to the floor passing through the shaft. This would assume that at each floor, the fire barrier discontinutes/continues at each floor deck.

Construciton is wood, Type Vb and the floor assembly is 1 hour. with a topping.

I can see both answers. 1) being the chute shall be a continuous void without the floor passing, etc. And 2) the construction need not be this and the benefit of creating a floor to floor fire blocking via continuing the deck through.

Both scenarios, the floor structure would not be exposed within the chase.

 

[steveray]

Don't forget the supporting construction......

706.4 Continuity of fire barrier walls.

Fire barrier walls shall extend from the top of the floor/ceiling assembly below to the underside of the floor or roof slab or deck above and shall be securely attached thereto. These walls shall be continuous through concealed spaces such as the space above a suspended ceiling. The supporting construction for fire barrier walls shall be protected to afford the required fire-resistance rating of the fire barrier supported except for 1-hour fire-resistance-rated incidental use area separations as required by Table 302.1.1 in buildings of Type IIB, IIIB and VB construction. Hollow vertical spaces within the fire barrier wall shall be firestopped at every floor level.

 

[brudgers]

Fire barriers have to provide protection from both sides. An unrated floor structure cannot be exposed from either side. In VB construction it is often possible to go full height with continuous shaftwall...i.e. bypass the floor completely by using larger CH studs. Use of the termination room provisions may also help with continuity.

 

[RLGA]

The OP states the floor assembly is 1-hour. I assume the shaft is also 1-hour fire barriers; thus, it would be okay. If the shaft is required to be 2-hours, then there is a problem, since the supporting floors do not have an equal rating.

 

[steveray]

Thanks Ron....missed that, saw VB and figured on an unrated structure....

 

[lunatick]

Actually is VA, started out as VB.

I fully suppressed with 13R system.

And with 419 (quoting from memory) this R occupany short enough to only require 1 hour floors and bearing walls, etc.

I ask this for some seem to interpret Shafts as being constructed of a Fire Wall and not a Fire Barrier. Now while I can understand the rationale for elevators and stairs. When dealing with lesser shafts for these items, it doesn't make sense for the shaft about a chute.

 

[Builder Bob]

Be careful as the 13 R does not protect the wooden (floor trusses) structural members, this sprinkler system only provided limited protection in occupiable areas and is designed for life safety, not property protection.