Plumbing codes can be confusing.
To confirm your DIY renovation is up to code, check out this guide to common plumbing codes.
Plumbing is the most complicated aspect of most bathroom andkitchen remodeling projects.
Credit: Jay Wilde
To prevent dangerous and unhealthy conditions, plumbing must conform to building codes.
TheNational Uniform Plumbing Codeapplies generally to the entire country.
You must also follow local codes, which could be more stringent.
When planning your kitchen or bathroom project, request information about local plumbing codes from your local building department.
Then follow these guidelines to check that your remodel abides by the proper plumbing codes.
Common Plumbing Codes
Common codes mainlyfocus on venting.
After all, drainpipes that are not properly vented will run sluggishly and couldrelease noxious fumes into the house.
Codes might require that vent pipes slope 1/8 inch per foot.
Some codes allow level vents.
Use Purple Primer
Pipes that are glued without primer eventually will leak.
Apply primerwhen joining PVC pipesto ensure a secure hold.
Some plumbing codes require you to verify that primer was used.
Choose a purple-colored primer so the inspector can quickly tell that the pipes have been sufficiently primed.
Be sure to use special drain fittings, such as a closet bend, so wastewater can flow smoothly.
Inspectors will have specific fitting requirements for different fixtures.
Avoid Cutting Notches in Joists
Cutting a notch in a joist greatly weakens it.
Whenever possible, bore holes through joists instead.
Whether notched or bored, long spans will likely need doubled joists.
Install Cleanouts
A drain cleanout provides a convenient access point to a pipe.
Plumbing codes call for cleanouts at various points so drains can be easily augeredin case of a clog.
Some inspectors will simply pour water through the pipes.
Other inspectors require that the line be plugged with an inflatable drain plug and the system filled with water.
If necessary,install an access panel.
The most common location for an access panel is behind a tub or shower.
Use the Correct Transition Fitting
When changing pipe materials, use the correct transition fitting.
Without a dielectric union (shown above), the joint between galvanized and copper pipe would quickly corrode.
Here, a ball valve has replaced a gate valve.
Consider Water Hammer Arresters
Water hammer arresters might be required for appliancessuch as a washing machine.
Supply pipes could need to be cushioned wherever they run through or against a framing member.
This helps prevent pipes from shaking or clanging against each other when the water flow suddenly stops.
A water hammer arrester creates a cushion of air that helps absorb the shock.
A hose bib should have an interior shutoff valve.
All faucets and toilets must have individual stop valves.
This corroded old valve, for example, will need replacement or repacking.
Use Approved Clamps or Straps
Use approved clamps or straps to secure pipes.
To be safe, install more supports than are required.
Plumbing Codes for Pipes
double-check pipes are up to code by adhering to these guidelines.
Branch Pipes
These pipes run from the distribution pipes to the fixtures.
Different fixtures place different demands on supply pipes.
Each fixture has a demand rating based on fixture units (see chart).
As a general rule, run 12-inch supply lines to all fixtures except toilets and bathroom sinks.
These fixtures require 38-inch tubes.
If a toilet connects to a drainpipe, the pipe must be at least 3 inches.
Check local building codes.
Fixture Trap Size
A bathroom sink uses a 114-inch trap.
Showers and floor drains use 2-inch traps.
All other fixtures and appliances use 112-inch traps.
