New Construction Plumbing
A well-designed plan is essential for a trouble-free home plumbing system.
Plumbing works on the simple concept of “water in - water out.” In a new home, the plumbing system features three main components, the water supply system, the drainage system and the appliance/fixture set. In most communities, in order to install plumbing, you must be a licensed plumber or you must work under a licensed plumber who approves and oversees your work. Local codes determine standard plumbing procedures, but a new home’s fixture placement, pipe routing diagram and pipe size depends on the home’s individual layout.
Sewer accommodation stubs are set before pouring the concrete foundation, but the bulk of the plumbing takes place later. The rough-in plumbing phase, which occurs in conjunction with the wiring and duct installation phase, takes place after the framing is complete, but before hanging drywall. This is the time to install main drains in floors and connect them to the stack. Rough-in drain fittings install now for sinks and tubs. This is also the time to install water supply pipes or tubing and set toilet flanges.
Because they’re often too large to set once walls and doorways are framed, tubs and tub/shower units are typically set before framing the walls. Since a lot of construction has yet to take place, cover these fixtures with cardboard or even old blankets or rugs to protect them from scratches. Set and connect sinks and commodes last, after finishing the walls and laying the flooring.
Water Supply System
The main pressurized water supply line enters the house below frost line, then splits into two lines; one supplies cold water and the other connects to the hot water heater. From there, the two lines supply hot and cold water to each fixture or appliance. Some homes have a water supply manifold system featuring a large panel with red valves on one side and blue valves on the other side. Each valve controls an individual hot or cold tube that supplies water to a fixture. Using a manifold system makes it simple to shut off the supply of water to one fixture without shutting off water supply to the whole house.
A main vent-and-soil stack, which is typically 4 inches in diameter, runs vertically from beneath the ground floor to above the roofline. Waste drains connect to the stack, directing waste downward to the main sewer drain, which then exits the home below frost line and ties into the municipal sewer system or runs to a personal septic system.
Without a constant source of air, water locks can form in drainpipes, causing clogs. All drains require ventilation, but a single vent, usually installed behind a sink, can serve additional fixtures and appliances that connect within 10 feet of a common drain line. Vent pipes, which are generally 2 inches in diameter, connect to the vent-and-soil stack in the attic. When a fixture sits too far from a common vent, it requires an additional vent pipe, which connects to the stack or exits the roof separately, depending on the home’s layout.
A drain trap is a U-shaped pipe that connects to the bottom of a sink, shower or tub drain. A trap retains a small amount of water that prevents smelly sewer gasses from backing up into the house. All plumbing fixtures require drain traps except the commode, which comes with an internal trap in its base.