The
letters DWV in building construction stand for Drain, Waste, Vent.
It is that part of a plumbing system that removes waste from a home
and vents, at the roof the odors created by the waste.
Once
upon a time, DWV systems were manufactured strictly from cast iron
and lead and sometimes copper and brass metals. Today, the products
include plastic DWV parts which are especially designed with the
do-it-yourselfer in mind. The plastic DWV systems go together as
easily as an Erector Set. The products are lightweight, easy to
cut and cement, and they are resistant to chemicals and corrosion.
The plastic material is also resistant to fungi, bacterial action,
and bad soil conditions. In short, plastic DWV systems should be
considered when adding any new plumbing to you home that utilizes
drain, waste, and vent pipes.
This
article deals specifically with the basics of working with plastic
DWV materials. These include PVC (polyvinyl chloride), CPVC (chlorinated
polyvinyl chloride), and ABS (acrylonitrile-butadiene-styrene).
SPECIAL NOTE: Plastic pipe and fittings are accepted by most
national Plumbing Codes, but some local codes will not accept it.
Plumbing codes, sometimes called sanitary codes, are necessary to
protect the health of homeowners. The restriction on plastic pipe,
if any in your community, probably comes from trade groups- not
that the products are inferior. Be sure to check with the Plumbing
Department of your community government about these codes before
you buy product and start working with it.
ASSEMBLY
PROCEDURES:
DWV pipe is easy to assemble fast. Here are the procedures you should
follow:
- Measure
and estimate the amount and size of pipes and fittings you will
need for the project.
You will find two types of DWV pipe: Schedule 30 and Schedule
40. Schedule 30 pipe is designed to fit inside a 2x4 stud wall.
Schedule 40 is designed to fit inside a 2x6 stud wall. Buy accordingly.
Pipes and fittings are solvent welded. Buy Schedule 30 adhesive
for Schedule 30 pipe, or Schedule 40 adhesive for Schedule 40
pipe, or a "universal" cement that may be used for both types.
Because plastic pipe tends to expand and contract with heat and
cold, be sure to allow about 1/4-inch clearance in your measurements
when running pipe through floors, ceilings, and framing members.
Lengths of larger diameter pipe set horizontally should be supported
with hanger straps about every 4 feet or so. Support vertical
runs of pipes as needed.
- Measure
twice. Cut once. When you are absolutely sure that you have made
the right measurements, cut the pipe to size, using a hacksaw
with a fine tooth blade set in the saw with the teeth pointing
toward the front of the saw frame. The cut should be made on the
forward stroke of the saw.
If you have a miter box, use the box to make square cuts. If not,
keep the cuts as square as you can.
- Deburr
the plastic edges made by the saw cuts. We recommend medium grit
abrasive (sandpaper) for this job. We do not recommend a knife
or file, both of which can cut into the "good" plastic. The trick
is to remove just the burrs; try "buffing" the edges lightly with
the abrasive paper.
- Make
a "dry" run of the project by assembling the pieces WITHOUT adhesive.
If the measurement is a tad "long," you can make cutting adjustments
at this point. If the measurement is a tad "short," you can recut
a small length to adjust the run accordingly.Also at this time,
with a wax China marker, run a short line onto the fittings and
the pipe. This mark will be used for aligning the pipe in the
fittings when they are assembled with the adhesive. When you're
perfectly satisfied that the project fits tightly together, disassemble
the pieces.
- With
a fairly narrow clean paintbrush, apply the adhesive to the inside
of the fitting and the outside of the pipe. A "medium" coating
is plenty. Don't skimp on adhesive, but don't slop it on the parts,
either.
- Assemble
the pipe and fittings, using the China marker lines for alignment.
Once the pipe is in the fitting, twist the pipe or fitting slightly-about
1/4-inch, or so to "spread" the adhesive. You can offset the China
marker lines slightly when you put the pipe in the fitting and
then twist either to align the lines.
Once the pipe/fittings are together, you can't pull them apart.
That's why it is so important that your measurements are accurate
and the reason for the "dry run." If you have made a mistake,
the only way to correct it is to cut out a piece of the run and
recouple it with a straight fitting or add more pipe to two fittings.
If you find yourself in this situation, mark and cut the pipe
between the new marks to the measurement of a slip coupling. Slip
the coupling onto the pipe, leaving about 2-inches of the pipe
ends exposed for the cement. Heavily coat the pipe with adhesive
and slip on the coupling. Then slide the coupling into position.
PROJECT
DATA/BACKGROUND:
Since we don't know what DWV project you will undertake, we can't
give you specific DWV design and detail information. However, on
the next pages you will find several typical projects involving
DWV products. Hopefully, you can use this data to help plan and
construct your project.
As
background, explore the Plumbing Department of a home center, looking
and handling the various DWV products on display. By doing so, we
think that you'll become better acquainted with these products,
and, therefore, see how they can be adapted to specific projects
that you have planned for your home.
When
figuring pipe size remember that pipes too small can't carry the
drainage load. Pipes too large will tend to clog. "Average" drainage
pipe sizes are:
Toilet:
3 inch pipes.
Bathtubs:
2 inch pipes.
Kitchen sinks: 1 1/2-inch pipes.
Lavatory: 1 1/2-inch pipes.
Floor drains: 1 1/2-inch pipes.
Laundry drains: 1 1/2-inch pipes.
Soil pipe: 3 inch pipes.
Sanitary tees: 3 inch pipes.
Vent stacks: 3 inch pipes.
Be
sure to check local plumbing codes concerning sizes. The list above
must be considered "average.
