Run the Line Without Joints
You can run PEX line as you would in a conventional plumbing system, with 3/4-in. main lines and 1/2-in. branch lines. You can also use a “manifold” system, where you run a 1/2-in. line to each fixture from a central spot.
Run your main lines first. If you're running PEX through joists or studs, drill 3/4-in. holes for 1/2-in. piping and 1-in. holes for 3/4-in. piping. Have a helper feed the line to avoid kinks and snarls. Some manufacturers recommend adding abrasion clips at each hole. You must use them for PEX that goes through metal studs, and nail protection plates when the tubing runs within 1-1/2 in. of the face of a stud or joist. Once you've run your main line, go back and mark the location of each branch line, leaving a 1-in. gap for the barbed tee.