Installing PEX Pipe
and Fittings
Installing PEX differs in several ways from
installing rigid pipe such as PVC, CPVC, and
copper:
• Measurements can be less precise.
• Because PEX is flexible, bends can often be
made without the need for ells.
• Joints are made with crimp rings and a
special crimping tool.
• Because PEX is flexible, horizontal runs
tend to sag even when the correct number
of straps are installed.
PEX is available in colors. It is helpful to use
different colors for hot and cold water lines.
Also, some manufacturers make straight
lengths of PEX that are useful when a short
length of tube needs to be installed. Different
brands of PEX tube, fittings, and crimp rings
may not be interchangeable. Therefore, it is
important to install all components from the
same manufacturer.
Thermal Expansion and
Contraction
PEX expands and contracts approximately
1″ for every 100′ of tube for every 10°F change
in temperature. This is nearly three times the
expansion and contraction rate of PVC. There-
fore, it is essential that provisions be made for
expansion and contraction. Several techniques
of providing for expansion are shown in
Figure 20-22. When an expansion loop is
installed in a wall cavity or between floor joists,
it is important that adequate space remains
around the loop so that it will not bind.
When PEX passes through openings in the
frame, it is recommended that sleeves be
installed to prevent wear on the tubing that
results from the expansion and contraction
movement of the pipe. If PEX is installed in
metal studs, it is absolutely essential that
sleeves be installed. The tube is, otherwise,
likely to be cut.
Measuring PEX
Installing PEX tube is more like installing
electrical wire than plumbing pipe. Take care
when uncoiling PEX not to kink the tube. Once
uncoiled, run the tube through the framing to
the point where one end can be connected to a
stub-out or other fitting. Make the connection
Chapter 20 Installing Water Supply Piping
365
Figure 20-22. Loops and offsets are effective means
of allowing PEX to expand and contract.
Studs or
joists
PEX tube
Leave space
between tube
and framing