ebuild Guide to Toilet SpecificationsSpec Guide: Toilets

    Toilet selection for home-builders and remodeling contractors is often influenced by room size and layout, the primary question is what will fit in the allotted space. Beyond dimensions, the other factors to consider include how the fixture is installed, configuration, bowl style, type of flushing system, ADA compliance, color and style.

    For most toilets, the key generic specifications include:

    • Rough-in, which is the measurement from the wall behind the toilet to the center of the waste pipe in the floor.

    • Mounting type, which captures whether the toilet is bolted to the floor or is a wall-mounted unit that is attached to the wall behind the toilet.
    • Configuration describes how the toilet is constructed. Most toilets are constructed as either one-piece or two-piece fixtures.

    • Bowl style, which captures the shape of the bowl.
    • Flushing system, which is the method used to evacuate the bowl.

    • ADA compliance indicates the toilet meets the requirements set forth by the Americans with Disabilities Act.

    The measurement from the wall behind the toilet to the center of the waste pipe is known as the rough-in dimension. The standard is 12 inches, although some older homes may have a 10-in. or 14-in. rough-in dimension. This dimension is critical for selecting the correct toilet, as there is no way to modify a toilet with an incorrect rough-in for acceptable installation.

    Mounting Type
    Toilets are designed to be mounted in one of two ways, either bolted to the floor (floor-mount) or bolted to the wall (wall-mount) behind the toilet. Floor-mounted toilets are the more common and use a through-floor waste outlet. A wall-mount toilet uses a rear waste outlet and has the advantage of leaving an unobstructed area under the toilet.

    Toilets come in one-piece or two-piece construction. A one-piece unit, also known as a low-profile toilet, has an integral tank and bowl. One-piece toilets offer the advantage of easy cleaning because there are no seams or crevices to trap debris.

    A two-piece, or close-coupled, toilet has a separate tank and bowl that bolt together. The components are sold separately and both can generally be purchased for less than the cost of a one-piece toilet. An advantage of a two-piece toilet is you can easily replace one portion of the toilet if it is damaged.

    Bowl Style
    Toilet bowls are available in two basic shapes—round and elongated. Round bowls are a little smaller than elongated bowls, allowing you to save some space in the bathroom. An elongated bowl has an oval shape and is generally around 2 inches longer than a round bowl. Elongated bowls are considered more comfortable to use and allow for a larger water area in the bowl.

    Flushing System
    All new toilets sold in the United States are required to use no more than 1.6 gallons per flush, so effective bowl cleaning relies more on the flushing method than the volume of water. The two standard flushing systems are gravity and pressure-assisted. A gravity-flush system uses the weight of the water in the tank to clean the bowl. A pressure-assisted system relies on pressurized air to force the water from the tank with greater pressure than a gravity-flush system.

    There are advantages and drawbacks to each type of system. A gravity system is simple to maintain and inexpensive to repair. However it may be more likely to clog in certain circumstances. A pressure system will better clean the bowl but can be noisy, and when repairs are needed, the cost will be greater than for a gravity system. Another concern with a pressure-assisted system is adequate domestic water pressure; at least 25 psi are required for most toilets.

    ADA Compliance
    The two standards set forth by the Americans with Disabilities Act that apply to a residential toilet are the height to the top of the seat and the location of the flush controls. The top of the seat must be at least 17 inches and no more than 19 inches above the floor. The flush controls cannot be mounted above 36 inches from the floor and must be mounted on the "wide," or unobstructed, side of the toilet.

    Additional factors to consider when selecting a toilet include the diameter of the flush valve, the size of the trapway and whether the trapway is glazed or not. A larger diameter flush valve will allow a higher rate of water flow. A larger trapway, especially one that is glazed, will help to reduce clogs.

    Toilet Specifications Resources:
    American Society of Plumbing Engineers

    National Association of Plumbing, Heating, Cooling Contractors

    National Kitchen and Bath Association

    Plumbing Manufacturers Institute

    Valve Manufacturers Association of America