How Is the Plumbing Done for a House Built on a Cement Slab?

First Steps

• An accurate, finalized floor plan is essential before starting any plumbing work. Once excavation is complete, take careful measurements for the location of each drainage and supply outlet. Consider the thickness of the finished walls and height of the finished floor when determining the location of your connection points.

Trenching

• Remove large rocks and debris from the bottom of all trenches prior to running pipes. Time and pressure can cause rocks or other hard objects to pierce underground plumbing. Locating and repairing a leak under a slab is an expensive, difficult process. Trenches for waste lines must be installed with a constant slope from the intake to the effluent point where they join the sewerage or septic system to maintain a constant flow.

Pipes

• Pressure-test water supply lines and connections before burying them. When using copper, tubing is best since it can be installed as a single point-to-point run. Reducing the number of soldered connections reduces the number of possible failure points from a less than perfect joint.

Backfill

• Pay careful attention to the quality of material used to cover the pipes once installed. The same rocks and debris that can damage a pipe in the bed of the trench can compress against the top of the pipe when the concrete foundation is poured.

Underground Advantages

• Burying household plumbing supply lines underneath the foundation reduces the risk of freezing and may be a good option in colder climates. Local building codes specify the minimum depths required for plumbing installation. Following these recommendations drastically reduces the danger of damage to the plumbing from cold weather.