two story shaft?

[Examiner]

Given:

Type III-B but it is small enough to be Type V-B

Occupancy Use: Business

Two Story

The building has a hip roof system out of wood trusses.

The first floor Restroom chase will terminate at the bottom of the 2nd floor. However, a shaft the same width of the chase but not the same length of the chase will continue up through the 2nd floor to the 2nd floor’s ceiling.

I doubt there will be any firesafing at the floor penetration with the toilet exhaust duct.

Will a shaft rating be required if the plumbing vents and restroom exhaust are confined to be in the same shaft?

Will the shaft be required to extend to the underside of the roof deck?

 

[MarkRandall]

Given:Will the shaft be required to extend to the underside of the roof deck?

No

707.12 Enclosure at the top. A shaft enclosure that does not

extend to the underside of the roof sheathing, deck or slab of the

building shall be enclosed at the top with construction of the

same fire-resistance rating as the topmost floor penetrated by

the shaft, but not less than the fire-resistance rating required for

the shaft enclosure.

Will a shaft rating be required if the plumbing vents and restroom exhaust are confined to be in the same shaft?

Shafts not required for plumbing vents, maybe for exhaust vents, but we're talking a two story structure, so I think you may find enclosures are not required. Check out the exceptions.

 

[peach]

It probably needs to be a shaft; if it's less than 4 stories, probably only 1 hour rating (or do the fire blocking); IBC 707.4

 

[mtlogcabin]

If it is a non fire rated floor assembly then a shaft is not required

716.6.3 Nonfire-resistance-rated floor assemblies.

Duct systems constructed of approved materials in accordance with the International Mechanical Code that penetrate nonfire-resistance-rated floor assemblies shall be protected by any of the following methods:

1. A shaft enclosure in accordance with Section 708.

2. The duct connects not more than two stories , and the annular space around the penetrating duct is protected with an approved noncombustible material that resists the free passage of flame and the products of combustion.

3. The duct connects not more than three stories , and the annular space around the penetrating duct is protected with an approved noncombustible material that resists the free passage of flame and the products of combustion and a fire damper is installed at each floor line.

 

[MarkRandall]

Thanks mtlogcabin,

I knew that was in there somewhere. I didn't want to take the time to find it to add it to my response, but I was sure the last two story, Type V-B building I designed did not require shafts.

 

[Examiner]

Thanks for the input. I will have to go over this with the inter Architect and make sure the Mech eng knows if a shaft or filling in the annular space is to be detailed.