BCAB #1365 - Combustible Waste Arms in DWV System, Sentence 3.1.9.4.(3)

October 19, 1994

BCAB #1365

Re: Combustible Waste Arms in DWV System, Sentence 3.1.9.4.(3)

Project Description

The project in question is an apartment building under Part 3 of the code. Combustible (ABS) pipe has been used for the waste arms from the kitchen sinks and the standpipes and P-trap for the washing machines. These pipes are located within non fire rated walls within each suite. The remainder of the DWV system, including all penetrations of fire rated assemblies, is of noncombustible piping.

Reason for Appeal

Sentence 3.1.9.4.(3) stipulates that, except as permitted in Sentences (4) to (6), combustible pipe cannot be used in a drain waste and vent system if any part of that system penetrates a fire separation with a fire resistance rating.

Appellant's Position

The appellant contends that the 11/2 ABS kitchen waste arms and washing machine standpipes should be acceptable as they present no hazard. The appellant points out that combustible plastic laundry boxes are permitted in these walls so why not the plastic pipe?

Building Official's Position

The building official maintains that the waste arms and standpipes are part of the DWV system and because the system penetrates fire separations the entire system must be of noncombustible pipe as required by Sentence 3.1.9.4.(3). Sentences 3.1.9.4.(4), (5) & (6), which allow combustible pipe in some circumstances, are not applicable to the circumstances in this case.

Appeal Board Decision #1365

As in several previous appeals (see #1205, #1260 & #1280) it is the determination of the Board that Sentence 3.1.9.4.(3) is applicable and does not permit the kitchen waste arms or washing machine standpipes and P-traps to be of combustible plastic pipe because the DWV system penetrates fire separations. The Board recognizes that this Sentence is very restrictive and imparts unreasonable requirements on the DWV system but a code change is required to correct this problem.

George R. Humphrey, Chair