The height of the showerhead stub-out is
dependent on the type of shower enclosure
that is installed. Often, the showerhead is
installed above molded fiberglass tub/shower
units to avoid cutting an opening in the fiber-
glass. Likewise, the tub spout is installed above
the tub rim so that it goes through the finished
wall materials (such as tile, cultured marble, or
sheet plastic) and not the tub itself. Manu-
facturer’s directions and the plans for the bath-
room should provide the information neces-
sary to position the drop ear ells correctly.
The drop ear ells for the showerhead and
tub spout have internal pipe threads at the
outlet so that threaded pipe or fitting can be
installed during the finished stage of plumbing
installation. Close the pipe for testing by
installing and capping 1⁄2″ pipe nipples, long
enough to extend 3″ inside the finished wall. It
is essential that the drop ear ells be securely
fastened to the blocking, because of the force
that must be applied to install the finished
components.
The valve and all four of the pipes leading
from it can be installed at this point. The lower
vertical hot and cold pipes can be extended
through the sole plate to be marked before they
are cut and permanently installed. Once this
work is completed in the first bathroom, the
tub/shower valve in the second bathroom can
be installed in the same manner. The connec-
tions to the hot water pipe below the floor can
then be completed and the cold water pipe can
be installed.
The rough-in for the two lavatories is very
similar to the tub/shower installation. The
basic difference is that a valve is not installed at
this time. Rather, the hot and cold water pipes
are stubbed out in the same manner as the
kitchen sink. Check the rough-in dimensions
and proceed with the offset in the hot water
pipe in the same way as in the tub/shower
installation.
The next task is to complete pipe runs to the
hot and cold water piping on the underside of
the floor frame. Face-to-face measurements
plus fitting allowances determine the length of
pipes. In cases where one length of pipe is not
sufficient, a coupling is needed to join two
lengths of pipe. The cold water pipe extending
from the bathroom to hose bibb A must also be
installed. A FIPT adapter is needed to attach
the hose bibb. The siding on the outside of the
house must be installed before the hose bibb is
attached because it fits over the siding. The
pipe can be capped inside the foundation so it
will be ready for testing. Once the siding is
installed, the cap can be cut off and a coupling
and short length of pipe may be used to extend
the pipe run to the hose bibb.
Before testing the system, the final step is to
check that all joints have been made correctly,
that caps are installed on all stub-outs, and that
the pipe is properly secured to the frame of the
building. Additional information about
spacing supports is provided in each of the
sections that follow, addressing the installation
of different kinds of pipe.
Installing PVC and
CPVC Plastic Pipe
and Fittings
Local code may permit the installation of
PVC for cold water piping. CPVC is required
for hot water. Most plumbers prefer to use
CPVC for both hot and cold water piping to
eliminate the risk of mixing the materials
during installation. Also, a different adhesive is
required for each of the types of plastic and it is
very easy to use the wrong material. To help
differentiate the materials, remember that PVC
is white and CPVC is tan in color.
Thermal Expansion and
Contraction
All materials change dimensions as a result
of fluctuating temperatures. Plastics expand
Chapter 20 Installing Water Supply Piping
359
Hose connections should be fitted with
backflow preventers on the discharge side of
the threaded outlet.
Code Note