BCAB #1434 - Combustible DWC pipe in storage garage, Articles 3.1.9.4. & 9.10.9.7.

February 19, 1997

BCAB #1434

Re: Combustible DWC pipe in storage garage, Articles 3.1.9.4. & 9.10.9.7.

Project Description

The project in question is a two-storey plus loft wood frame apartment building over an open air concrete storage garage. All the DWV pipe in the garage is combustible ABS while all the pipe within the combustible building above is cast iron. The transition from ABS to cast iron is at the underside of the concrete slab over the garage. All the penetrations of horizontal fire separations are fire stopped.

Reason for Appeal

Sentences 3.1.9.4.(3) and 9.10.9.7.(1) state that, with several exceptions, combustible piping shall not be used in a DWV system where any part of that system penetrates a fire separation. There are two exceptions which relate to this appeal:

1. Combustible DWV pipe can penetrate fire separations if the penetrations are sealed with a fire stop system which provides an F rating equal to the fire resistance rating of the separation and the F rating has been determined in conformance with CAN4-S115, "Standard Method of Fire Tests for Fire Stop Systems" and

2. Combustible DWV is permitted to penetrate a horizontal fire separation if it leads directly to a noncombustible water closet through a concrete floor slab.

Appellant's Position

The appellant contends the DWV system as installed with combustible ABS pipe running below the concrete floor slab separating the garage from the residential units above and noncombustible cast iron penetrating the slab and wood floor systems above it is acceptable. All the penetrations are fire stopped.

Building Official's Position

The building official maintains that Articles 3.1.9.4. and 9.10.9.7. do not permit the combination of combustible and noncombustible pipe as installed. Combustible pipe with F rated penetrations would be permitted throughout the building or a single transition from plastic to cast iron could be made immediately above a rated floor with the plastic pipe penetration fire stopped with the appropriate F rating. Although Sentences 3.1.9.4.(5) and 9.10.9.7.(4) permit combustible DWV to penetrate a concrete floor slab if it connects directly to a water closet there is no defined end terminus. Therefore, the building official allows only the vertical portion of the water closet waste arm to be noncombustible.

Appeal Board Decision #1434

It is the determination of the Board that the noncombustible DWV pipe penetration of the fire rated concrete slab does not meet the requirements of Sentences 3.1.9.4.(4) and 9.10.9.7.(2). These sentences only permit combustible pipe penetrations provided they conform to CAN4-S115. The DWV system does not comply with Sentences 3.1.9.4.(3) or 9.10.9.7.(1) because the system contains combustible piping and parts of the system penetrate fire rated assemblies.

Sentences 3.1.9.4.(4) and 9.10.9.7.(2) only permit F rated combustible penetrations. If the plastic pipe passed through the slab with an S-115 fire stop assembly then converted to metal pipe above the slab it would comply with Sentences 3.1.9.4.(4) and 9.10.9.7.(2). The code would have to be revised to permit the metal to plastic conversion below the slab.

George R. Humphrey, Chair