Current through Register 1531, September 27, 2024
Penetrations by ducts and air transfer openings of a floor,
floor/ceiling assembly or the ceiling membrane of a roof/ceiling assembly shall
be protected by a shaft enclosure that complies with Section 708 or shall
comply with Sections 716.6.1 through 716.6.3.
716.6.1
Through penetrations. In
occupancies other than Groups I-2 and I-3, a duct constructed of
approved materials in accordance with the
International Mechanical Code that penetrates a
fire-resistance-rated floor/ceiling assembly that connects not more than two
stories is permitted without shaft enclosure protection,
provided a listed fire damper is installed at the floor line
or the duct is protected in accordance with Section 713.4. For air transfer
openings, see Exception 7 to Section 708.2.
Exception: A duct is permitted to penetrate
three floors or less without a fire damper at each floor,
provided such duct meets all of the following requirements:
1. The duct shall be contained and located
within the cavity of a wall and shall be constructed of steel having a minimum
wall thickness of 0.0187 inch (0.4712 mm) (No. 26 gage).
2. The duct shall open into only one
dwelling or sleeping unit and the duct system shall be
continuous from the unit to the exterior of the building.
3. The duct shall not exceed 4-inch (102 mm)
nominal diameter and the total area of such ducts shall not exceed 100 square
inches (0.065 m2) in any 100 square feet (9.3
m2) of floor area.
4. The annular space around the duct is
protected with materials that prevent the passage of flame and hot gases
sufficient to ignite cotton waste where subjected to ASTM E 119 or UL 263
time-temperature conditions under a minimum positive pressure differential of
0.01 inch (2.49 Pa) of water at the location of the penetration for the time
period equivalent to the fire-resistance rating of the
construction penetrated.
5. Grille
openings located in a ceiling of a fire-resistance-rated floor/ceiling or
roof/ceiling assembly shall be protected with a listed ceiling
radiation damper installed in accordance with Section
716.6.2.1.
716.6.2
Membrane penetrations. Ducts and air transfer openings
constructed of approved materials in accordance with the
International Mechanical Code that penetrate the ceiling
membrane of a fire-resistance-rated floor/ceiling or roof/ceiling assembly
shall be protected with one of the following:
1. A shaft enclosure in accordance with
Section 708.
2. A listed
ceiling radiation damper installed at the ceiling line where a duct
penetrates the ceiling of a fire-resistance-rated floor/ceiling or roof/ceiling
assembly.
3. A
listed
ceiling radiation damper installed at the ceiling line where a
diffuser with no duct attached penetrates the ceiling of a
fire-resistance-rated floor/ceiling or roof/ceiling assembly.
716.6.2.1
Ceiling radiation dampers.
Ceiling radiation dampers shall be tested in accordance
with Section 716.3.1.
Ceiling radiation dampers shall be
installed in accordance with the details
listed in the
fire-resistance-rated assembly and the manufacturer's installation instructions
and the listing.
Ceiling radiation dampers are not required
where either of the following applies:
1.
Tests in accordance with ASTM E 119 or UL 263 have shown that ceiling
radiation dampers are not necessary in order to maintain the
fire-resistance rating of the assembly.
2. Where exhaust duct penetrations are
protected in accordance with Section 713.4.1.2, are located within the cavity
of a wall and do not pass through another dwelling unit or
tenant space.
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.
Exception: Fire dampers are not
required in ducts within individual residential dwelling
units.
