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wood blocking in shaft

F

Frank Karp

Member
Joined
Oct 20, 2011
Messages
13
Location
Rhode Island
Can 2 x 4 wood blocking (not fire retardant treated) be left inside a 5 story, 2 hr shaft of a 5A apartment building? Evidently, it was installed to support future grease duct. So, grease duct is being installed with a 2 hr ceramic blanket and the installer wants to connect steel angle duct support brackets to existing blocking. Thought I'd find something in the 2012 IBC that would prohibit combustibles within shaft, but nothing yet. Relative to IMC 506.3.3, can blocking be considered structure?
 
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Frank Karp said:
Can 2 x 4 wood blocking (not fire retardant treated) be left inside a 5 story, 2 hr shaft of a 5A apartment building. Evidently, it was installed to support future grease duct. So, grease duct is being installed with a 2 hr ceramic blanket and the installer wants to connect steel angle duct support brackets to existing blocking. Thought I'd find something in the 2012 IBC that would prohibit combustibles within shaft, but nothing yet. Relative to IMC 506.3.3, can blocking be considered structure?
Click to expand...
IBC Section 708
 
Frank-

Pull the E.S. report for the shaft liner product proposed to be used. I've had good luck finding construction details that will help in these situations.

Good Luck!

ZIG
 
Shaft is installed and building is occupied Zigmark. Rider Rick: One side of the 5' x 5' x 5' triangular shaft has an open 2 x 4 stud wall with a stud at each corner and and then 2 more equally spaced between them. Every floor there is single 2 x 4 plate. It all sits on the concrete beam at bottom of shaft (first floor ceiling.)
 
Install per approved ceramic blanket instructions; may very well allow zero clearance to combustible materials in accordance with IMC section 506.3.6

506.3.6 Grease duct clearances.

Where enclosures are not required, grease duct systems and exhaust equipment serving a Type I hood shall have a clearance to combustible construction of not less than 18 inches (457 mm), and shall have a clearance to noncombustible construction and gypsum wallboard attached to noncombustible structures of not less than 3 inches (76 mm).

Exceptions:

1. Factory-built commercial kitchen grease ducts listed and labeled in accordance with UL 1978.

2. Listed and labeled exhaust equipment installed in accordance with :Next('./icod_imc_2012_3_par045.htm')'>Section 304.1.

3. Where commercial kitchen grease ducts are continuously covered on all sides with a listed and labeled field-applied grease duct enclosure material, system, product or method of construction specifically evaluated for such purpose in accordance with ASTM E 2336, the required clearance shall be in accordance with the listing of such material, system, product or method.

Francis
 
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Francis, Per the building inspector, we are good with the wrapped grease duct. The only question that remains: Can wood remain inside the shaft? Tx
 
Yes, that's the purpose for the shaft. How is it different than other combustibles inside shafts for PVC?

Another point the support brackets has to be allowed to be fastened to wood.

Francis
 
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