Cross-linked polyethylene, commonly known as PEX, comes in flexible red and blue tubes that supply water from a home’s water distribution center to individual faucets. The water distribution center features a manifold panel with numerous red valves on one side and the same number of blue valves on the other side. PEX water supply tubes, which are typically 1/2 inch in diameter, install easily between wall studs and in joist spaces. But if you’re running the tubes in a ceiling, perpendicular to the joists, you’ll have to drill holes, then pull the tubes through.
Things You'll Need
- PEX tubing
- Utility knife or shears
- Drill with 3/4-inch bit
- Chalk line
- Directional PEX fittings (optional)
- PEX crimper
Locate the stud space behind the sink, tub or other fixture from the attic. This is the vertical wall space where the ends of the PEX tubing will descend to meet the plumbing fixture. Make a mark on the top of the ceiling joist above this stud space.
Make another mark on the ceiling joist above the stud space where you'll bring the PEX tubing up from the floor. House layouts differ, but choose a path from the water distribution center to the fixtures that involves the fewest number of directional changes.
Snap two chalk lines across the top of the ceiling joists that you marked. The lines should be about 1 inch apart and parallel to each other. These are the ceiling joists that you will drill to accommodate the PEX tubing.
Measure 2 inches down from the top of each ceiling joist and drill two holes, one hole beneath each chalk line. Use a drill, fitted with a 3/4-inch bit.
Begin running the PEX tubing by inserting one end in the stud space behind the new plumbing fixture. PEX comes in large rolls, 100 feet and longer. Don’t cut the tubing yet, just pull it off the large roll as you need it. When you reach the ceiling joists, insert the end of the tube through the nearest hole in a ceiling joist and pull it through without kinking it. Since the holes are all in a straight line, the PEX should slide right through each joist.
Coax the PEX around corners where you must change direction from horizontal to vertical. PEX is flexible, but some corners are too sharp and the tubing might kink. If this occurs, you’ll have to cut the PEX at that corner and install a 90-degree angle corner fitting, called a “hard 90.”
Continue to pull the tubing along the path from the water distribution center all the way to the new plumbing fixture. Leave at least 1 foot of excess tubing before cutting the PEX from the roll.
Attach the ends of the PEX to the matching color valves on the water distribution center and to the hot and cold water faucets on the new sink or other fixture. All PEX fittings require compression, so you’ll need a tubing crimper to attach the ends and any hard-90 fittings you installed between the two points.
Tips & Warnings
- If possible, install plumbing fixtures so the water supply and drainpipes do not run along an exterior wall, especially if you live in a region where the pipes can freeze during the winter.
- Label each water supply valve on the water distribution manifold for future reference.
- If you're running PEX to more than one fixture, drill separate holes in the joists for each tube. Avoid drilling larger holes or cramming more than one tube in each hole.
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