BCAB #1737 - ABS Bathtub Drain/Overflow Through Concrete Slab, Sentence 3.1.5.16.(1)

September 24, 2013

BCAB #1737

Re: ABS Bathtub Drain/Overflow Through Concrete Slab, Sentence 3.1.5.16.(1)

Project Description

The project in question is a residential hi-rise of noncombustible construction. The appeal involves a drain for an acrylic bathtub employing an ABS drain/overflow assembly passing through the eight inch concrete slab. The ABS assembly from the tub overflow and drain penetrates the slab through an assembly incorporating a cUL classified firestop device and then connects to the noncombustible trap directly below the slab with a combustible flexible coupling. Most of the ABS overflow/drain pipe assembly is exposed above the slab but concealed under the acrylic bathtub.

Reason for Appeal

With some exceptions Sentence 3.1.5.16.(1) permits combustible (plastic) piping to be used in noncombustible construction provided it has a flame spread rating not exceeding 25 and, in high buildings, a smoke developed rating not exceeding 50. The one exception to the flame spread and smoke developed limits that could apply to this project is where the plastic pipe is “concealed in a wall or concrete floor slab.”

Sentence 3.1.5.17.(1) permits combustible plumbing fixtures such as an acrylic bathtub in noncombustible construction provided the material from which the fixture is made has a flame spread rating and smoke developed classification not more than that permitted for the wall surface of the room or space in which they are installed.

Appellant's Position

The appellant contends that the ABS drain assembly should be acceptable because it is either concealed in the concrete floor slab or concealed below the acrylic bathtub which does conform to required flame spread and smoke developed ratings. The appellant refers to several previous appeals from the 1980’s that he contends support his interpretation.

Building Official's Position

The building official maintains that Sentence 3.1.5.16.(1) clearly only allows combustible piping that has a flame spread rating of not more than 25 and a smoke developed rating of not more than 50 for hi-rise buildings. ABS pipe has a flame spread rating of 200 – 260 and is therefore not permitted. The building official also maintains that the ABS drain/overflow assembly is not part of the fixture and can’t rely on being concealed below the Code conforming combustible bathtub.

Appeal Board Decision #1737

It is the determination of the Board that the ABS drain/overflow assembly does not conform to the Code because it is neither part of the acrylic fixture nor concealed in the concrete floor slab.

George Humphrey, Chair