What's your BuildIQ: The Plumbing System

If you've ever had a leaky faucet, water hammer, or an overflowing toilet, then you understand the importance of having a quality plumbing system in a home. A poorly installed plumbing system can spawn problems that cause water damage and mold growth. Adhering to building code requirements and installing a plumbing system with important quality considerations in mind will help you to achieve happy customers and fewer callbacks.

Plumbing in a home includes two separate systems, one for water supply and one for waste drainage. One system carries water to fixtures and appliances, and the other removes solid and gaseous wastes from these same fixtures and appliances. The water supply system uses pressure to move potable water from the water service line and municipal water supply to the fixtures and appliances. To help maintain water pressure, the pipes within the home get increasingly smaller as they go from the water meter to sinks, showers, toilets, etc. When the pipes are correctly sized, the water pressure is stable, and the water flow is steady. Correctly sized pipes can help prevent water hammer—the loud banging noise that can occur when the water is turned on or shut off too quickly.

The sanitary drain system uses gravity to move waste and gases out of the home. Horizontal lines set with a slightly downward slope connect every water-using fixture and appliance drain to a waste stack, which drains into the house sewer line. Each fixture and appliance has a trap that blocks waste and gases from reentering the living space, as well as a vent that exhausts sewer gases.

The plumbing system has to adhere to building code requirements in order to pass inspection. A building inspector, for instance, will inspect and test the water supply system for code compliance and leaks during construction. In addition to meeting code requirements, however, the plumbing system should be installed with quality in mind. A quality plumbing system is less likely to lead to problems down the road.

Do you know the best practices for installing a quality plumbing system? The following questions will test your BuildIQ. Stumped, or want to learn more? Visit http://hz.buildiquniversity.com


A typical home plumbing system

1. Why must horizontal waste lines be sloped ¼-inch per foot?

A. To enable them to be attached tightly to the framing
A is incorrect. Drain lines are sloped so they'll drain quickly enough but not too quickly. Support to the framing is accomplished with mechanical fasteners and isn't related to drain line slope.

B. To make it easier for other mechanicals to fit within the wall systems
B is incorrect. Plumbing must share the space within the wall system with HVAC and electrical, however, accommodating other mechanicals is not the reason for sloping the drain lines. Drain lines are sloped so they'll drain just quickly enough to carry away both liquid and solid wastes.

C. To drain waste water quickly, but not too quickly
C is correct. Sloping less than ¼-inch per foot will cause water to drain too slowly. Sloping more than ½-inch per foot can cause water to drain too quickly and leave solid waste in the pipes.

2. What can prevent water hammer?

A. P-traps at every drain
A is incorrect. P-traps provide an effective trap seal that prevent sewer gases and vermin from entering the home through the drain line.

B. Correctly sized supply pipes
B is correct. Water hammer occurs when the water supply is cut off too quickly. Using large enough supply pipes will help to eliminate this issue.

C. Sloping the drain line ¼-inch per foot
C is incorrect. Correct slope of the drain line allows solid and liquid waste to drain effectively.

3. For a home with a basement or crawlspace foundation, the water supply system typically is inspected after the plumbing rough-in. For a slab on grade foundation, what is the timing?

A. After the underground plumbing has been laid
A is correct. This is the ideal time to inspect under-slab plumbing because problems can be identified and corrected before the slab is poured.

B. During the finish inspection
B is incorrect. This is very late in the construction process; under-slab plumbing is typically inspected before the slab is poured so that any problems can be identified without breaking up the slab.

C. Any time after the slab has been poured
C is incorrect. Under-slab plumbing typically is inspected before the slab is poured so that any problems can be identified without breaking up the slab.

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