The Plumbing Code is a part of the Building Code and provides minimum requirements for plumbing installations in buildings to protect health and prevent water or sewer damage. The plumbing code specifies that all materials, systems, and equipment installed must be free of defects and possess the necessary characteristics to perform their intended functions when installed. Plumbers need to stay abreast of new regulations that may govern the types of pipes and fixtures acceptable to local inspectors. The purpose of this chapter is to help you correctly interpret plumbing code requirements for types of piping materials that may be used in DWV systems.

Identifying Piping

Every length of pipe and every fitting must have cast, stamped, or indelibly marked on it the maker’s name or mark and the weight, class, or quality of the product, or be marked in accordance with the relevant standard. To help ensure the proper application of the different pipe materials, the code requires that these materials’ identification markings must be visible after installation.

Piping Types

The acceptable piping materials for sanitary drainage systems are clearly listed in three tables in the Plumbing Code: Tables A-2.2.5., A-2.2.6., and A-2.2.7. The tables identify the acceptable material by reference to the appropriate ASTM or CSA standard and whether or not they are permitted above ground inside a building or below ground under a building in drainage and venting systems. The standard must properly address all technical matters in regulating a given material for use in a plumbing drainage and vent system.

One of the concerns with installing DWV systems is the impact the piping material has on the fire-protection aspects of a building. The building code requirements for pipe penetrations distinguish between combustible piping materials, such as ABS and PVC, and non-combustible piping materials, such as cast-iron soil pipe and copper tubing.

Another concern is the ability of DWV piping to withstand service pressures. This is usually not an issue with gravity systems, but when working with a pressure sewer “forcemain,” it has some code restrictions. These systems are necessary when gravity flow is not sufficient to move sewage through a gravity line. Forcemains move wastewater under pressure using pumps or compressors located in lift stations. They convey wastewater from a lower to higher elevation or where construction of a gravity line would result in excessive excavation depths and prohibitive sewer line costs. The code requires that piping, fittings, and joints used in pressure sewer, forcemain, or sump pump discharge applications be capable of withstanding at least one and a half times the maximum potential pressure.

The following is a comprehensive list of piping materials used in DWV systems and the code requirements governing their use. The lists indicate:

• Permitted application with the letter P
• Non-permitted application with the letter N.

Fibrocement DWV Pipe

The material used to fabricate fibrocement pipe must conform to CAN/CSA-B127.3. This standard covers fibrocement Type 1 (Class 3000) and Type 2 (Class 4000) pipe and pipe fittings for installation in gravity-flow systems inside and outside of buildings, above and below grade

The pipe is formed under pressure and heat-cured in an autoclave. Using fibres rather than reinforcing steel provides adequate strength with lower weight. The standard was introduced in 2018 to replace the pipes that used asbestos as their reinforcing fibres.

DWV Application

Polyethylene Plastic Pipe

Polyethylene plastic (PE) piping is considered “flexible” pipe and can withstand large amounts of deflection without damage. For practical purposes, however, PE pipes are limited to 7.5% deflection or less, depending on the standard dimension ratio (SDR) and application. Using polyethylene pipe for drainage systems resulted from the fairly recent practice of “pulling” a new building sewer into the space occupied by an old sewer without digging a trench to do so.

DWV Application

Plastic Sewer Pipe

These applications include both single-wall and co-extruded dual-wall pipe with a smooth interior.

DWV Application

ABS (Acrylonitrile-Butadiene-Styrene) Pipe

Due to its combustible property, ABS is primarily used in non-rated combustible construction, such as single-family dwellings. It is available in solid-wall and cellular-core construction in Schedule 40 dimensions. When used in non-combustible construction, it must meet the requirements of the building code, which requires that all combustible piping in buildings be of non-combustible construction and have a flame-spread rating (FSR) of not more than 25.

Combustible piping used in a high-rise building is also required to have a smoke developed classification (SDC) of not more than 50. Plastic piping not meeting the required FSR or SDC is only allowed if it is concealed in a wall or concrete floor slab and does not project outside of the concrete, even if concealed behind other components. ABS piping has an FSR exceeding 25; therefore, it cannot be used in buildings required to be non-combustible.

Solid-Wall Application

Cellular-Core Application

PVC (Polyvinyl Chloride) DWV Pipe

PVC DWV piping may have an FSR of less than 25, but its SDC may exceed 50; therefore, it may be used in buildings required to be non-combustible but not in high-rise buildings. Several commercially available combustible pipes meet the required FSR.

Solid-Wall Application

Cellular-Core Application

PVC (Polyvinyl Chloride) Sewer Pipe (All Classes) Application

Profile Polyethylene Sewer Pipe

Profile wall pipe gains its strength through the geometry of the pipe wall. The pipe has a smooth interior wall with exteriors that may be ribbed or corrugated.

Application

Polyolefin Laboratory Drainage Systems

Polyolefin pipe is used in a wide range of medical and laboratory applications that require non-corrosive material. The two most common classes are polyethylene (PE) and polypropylene (PP).

Application

Cast-Iron Pipe

Cast-iron soil pipe is used primarily in non-combustible building construction for sanitary, storm drain, waste, and vent piping applications. Because cast-iron pipe that penetrates fire separations will not allow the passage of flames from one compartment to another, fire retardants and cut-off devices are not required.

Application

Copper Tubing

Copper tubing is available in both hard and soft tempers. Only hard copper tubing may be used for DWV systems. Copper tube must not be used for the fixture drain or the portion of the vent pipe below the flood level rim of a urinal.

Type K and L copper joints installed underground shall be made with either flared or compression fittings or be brazed using a brazing alloy within the American Welding Society’s AWS-BCuP range. Compression fittings are not allowed underground under a building because the joint cannot withstand building settlement.

Type K and L Hard Temper Application

Type M Hard Temper Application

DWV Types Application

Welded Seamless Steel Galvanized Pipe

Galvanized pipe is a variety of steel piping coated in a layer of zinc. While the layer of zinc over the steel was originally intended to help avoid corrosion, it has since been discovered that zinc has a tendency to react with the minerals in the water it carries, producing scale.

Application

Copper and Brass Pipe

These requirements refer to pipe that conforms to the same wall thickness standards as schedule steel pipe materials. If copper or brass pipes are used in drainage systems, they must use drainage fittings not threaded water fittings.

Copper and brass are two very similar-looking metals, but there are many occasions when it is useful to be able to differentiate between brass and copper pipes. Copper is a naturally occurring metal, while brass is an artificial alloy of copper and zinc mixed together.

Application

Lead Waste Pipe

Lead piping has not been commonly used since the 1950s, but it still has approved applications in the Plumbing Code. The code requires that when there is a change in size of a lead closet bend, the change shall be in the vertical section of the bend or made in a manner that prevents the retention of liquid in the bend.

Application

Self-Test D-1.4: Acceptable Pipe Material Application

Complete Self-Test D-1.4 and check your answers.

References

Skilled Trades BC. (2021). Book 2: Install fixtures and appliances, install sanitary and storm drainage systems. Plumber apprenticeship program level 2 book 2 (Harmonized). Crown Publications: King’s Printer for British Columbia.

Trades Training BC. (2021). D-1: Install sanitary drain, water and vent systems. In: Plumber Apprenticeship Program: Level 2. Industry Training Authority, BC.

Media Attributions

All figures are used with permission from Skilled Trades BC (2021) unless otherwise noted.