Running New Supply Lines

KEEP YOUR EYES ON THE BALL - Plumbing code doesn't allow either compression fittings or flexible line fittings inside the wall. Both must be accessible for repair and inspection.

Materials: Copper supply pipe, copper fittings, integral stops, copper tube straps and anti-vibration pads, brass screws, faucet assembly, shower tee, solder, flux, PVC P-trap, tub overflow and drain assembly, PVC primer and adhesive, bathtub, galvanized nails, 2x4 blocking, 1x3 ledger strips, silicone caulk

Tools: Electric drill, spade bits, tape measure, carpenter’s level, pencil, hammer, MAPP torch and striker, tubing cutter, soldering kit, fiberglass flame barrier, hammer, screwdriver, saber saw, PVC cutter, gloves, safety glasses

Running new supply lines requires planning in order to choose the best route for the pipes and break the job down into manageable phases. Hot and cold supply lines can be either copper (as shown here), CPVC, or, if code allows, PEX. You must decide the most convenient point to break into existing service and then track the pipe runs to the point of the new installation (in this case, a control riser for a new bathroom). The closest point may not be the best choice—remember pipe is cheap.

The idea is to plan a run that does the least damage to existing walls and installations and therefore requires the least patching and repair. (Once you’ve planned the run, you may find it easier to install the system in the bathroom first and then connect the supply lines downstairs.)


• Plan ahead. Make a sketch of the installation.

• Create a tools and materials list.

• Purchase all materials and make everything you’ll need accessible before you begin work. (NOTE: The diameter of the pipe you’re installing must be the same as the existing supply line.)

• Turn off the water supply and drain the pipes you are cutting into to install the new lines.

• Mark the location of the new supply lines on the wall studs. Space the hot and cold water supply lines approximately 8 inches apart.

• Cut out sections of the existing supply lines and install T-fittings for connecting the new pipes.

• Cut and test-fit all the pipes and fittings before you solder the connections.

• Going through studs: Drill holes for the supply lines in the center of the studs, making the holes at least 1/4 inch larger than the diameter of the pipe you are running. Code may require larger holes in earthquake zones.

• Attaching to floor joists: Secure the pipes to the joists with hangers as you go to prevent stress.

Standard showerhead height is 6 ‘6 " from the floor, but you can place it wherever you choose. Standard spout height is 28", but it must be at least 6"above the finished top of the tub. Center both the spout and showerhead over the drain. If local code requires an inspection, make sure it is done before you close up the wails.

INTEGRALSTOPS - Integral stops are set screw-operated shutoff valves that can be installed as part of the valve body assembly. The advantage of using an integral stop is that you can access it by removing the escutcheon plate that covers the valve assembly.

1 DRILL HOLES FOR THE RISERS. Drill riser holes through the stud wall into the basement. The diameter of the holes should be at least 1A inch larger than the diameter of the riser to allow some flexibility when hooking up the supply lines. The type of faucet you're installing will determine the spread and placement of the riser holes.

2 INSTALL THE VALVE BODY. Make sure the faucet controls are centered and level. Do a dry assembly to make sure everything fits. The heat of soldering may damage the valve's internal parts; to prevent this, remove them if possible. If the valve attaches to a screw-in fitting, solder the first piece of pipe to the fitting before screwing the fitting to the valve.

3 INSTALL THE TOP BLOCKING. Blocking for a tub spout should be centered 6 inches above the top of the tub. Faucets installed more than 6 inches above the spout need separate blocking. The blocking should be level, at the correct depth inside the wall, and toenailed firmly to the studs. Blocking for the showerhead is usually about 6V2 feet above the floor, but you can adjust the height to suit your needs.

4 SECURE THE SPOUT AND SHOWER RISER TO THE BLOCKING. Connect all the pipes and fittings. Screw any brass fittings to the framing with brass screws to prevent the corrosion that occurs when dissimilar metals are in contact with each other.

5 RUN SUPPLY LINES TO THE RISERS. CUT PIPE LENGTHS. Test-fit each supply line, and mark adjustments on the piping. Take the runs apart and make the changes. Anchor the pipes securely to the joists as you make the runs, and solder in place.

PIPE DOWN IN THERE! Believe it or not, water running through pipes can make a lot of noise. To isolate it, slide plastic or felt fittings around the pipes wherever you attach them to the framing. Foam insulation designed to prevent frozen pipes will also minimize noise inside the wall.

WATER HAMMER - The banging caused by water pounding against a valve when you shut off the water is called water hammer. If it's a problem in your house, buy a commercial water hammer arrester, a small pipelike device that absorbs the shock.

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