and all pipe must be rigidly supported every
Continue to build up the vent stack, with as few
4 ft. and at each horizontal branch connection.
jogs as possible, until it eventually passes
Support pipes with rigid plastic pipe hangers
through a flashing unit set in the roof. For code
(p. 333), or plastic-pipe strap, as shown above.
requirements at the roof, see “Vent Termination”
Support stocks at the base and at midstory by
on p. 339.
strapping or clamping the pipe to a 2x block run-
ning between the studs or by using stack clamps.
TesTIng The Dwv sysTem
Run the tub branch drain to the subfloor
Once you’ve assembled all pipes of the DWV sys-
opening where the tub trap arm will descend.
tem and connected it to the sewer main—but
Pipe stub-outs for lavs and sinks should stick out
before hooking up fixtures—test for leaks. A com-
into living spaces 6 in. or so; you can cut them off mon test is to fill DWV pipes with water, after
or attach trap adapters later. All branch drains
capping the stub-out for each fixture drain and
end in a sanitary tee. The horizontal leg of the tee blocking the combo fitting at the foot of the
receives the trap arm from the fixture, and the
building drain—as described later in this section.
upper leg of the tee is the beginning of the
Use a garden hose to fill the largest stack: All
branch vent.
DWV pipes are interconnected, so you need fill
Vent runs. Next, assemble vent runs, starting
only one stack to fill all. Should you see leaks,
with the largest vent—often the 2-in. or 3-in. pipe drain the system, fix the leaks, and refill. If you
rising from the combo fitting below the closet
see no leaks, allow the water to stand at least
bend. Individual branch vents then run to that
overnight or until the inspector signs off on
vent stack, usually joining it in an inverted tee fit-
your system.
ting, typically 4 ft. to 5 ft. above the floor. Support
There are several types of pipe cap. Reusable
all stacks in midstory with clamps or straps.
rubber caps or plugs eliminate the need for glu-
Horizontal runs of 11⁄2-in. branch vents must be
ing. A jim cap fits over the end of a pipe and
plumbing
343
tightens with a ring clamp. Test plugs fit into pipe the building drain. As shown in the top photo
ends and are expanded by a wing-nut assembly.
below, this tool has two rubber balls that can be
The most common and least expensive, however,
expanded or contracted by turn-screws on the
is a glue-on cap that fits inside a DWV pipe stub.
shaft. Insert the balls so that the forward one
Allow pipe cement to dry a day before filling
lodges in the drainpipe, then expand that ball;
pipes with water. When the test is completed,
the second ball should block the open leg of the
S a f e T y a l e R T
drain the system and cut off the small sections of combo. To release the water, contract the balls of
drainpipe in which caps are glued. Where a stack the double dynamiter in the order in which you
electrical service is often
is several stories high, this is the only type of cap
expanded them. Loosened, the forward ball will
grounded to metal water-supply
guaranteed not to be dislodged by a weighty col-
allow the test water to run down the drain;
pipes, meaning the pipes could
umn of water.
releasing the second ball allows you to remove
become energized. To avoid
The linchpin to this pipe-filling test, however,
the tool. Label the respective turn-screws so you
shocks when cutting into such
is a double dynamiter, a spring-loaded double test don’t confuse them: If you release the second ball
pipes, use a cordless reciprocat-
ing saw with a metal-cutting
plug that fits into the T-Y combo at the foot of
first, you may get a faceful of water.
blade, rather than a corded saw.
If there are finish ceilings in place below new
The cordless saw’s plastic casing
pipes and you don’t want to risk wetting them
also will insulate against shocks
with a failed connection, use an air-pressure test
if pipes are energized, as will
in which all openings (including stacks) are
rubber gloves. Before cutting,
sealed. Typically, an inflatable bladder attached
shut off the water and open
to a gauge is inserted into a cleanout at the base
faucets to drain the pipes.
of the soil stack, and air is pumped into the DWV
system. If the gauge shows no pressure loss over
a given period, the inspector signs off.
Roughing-in Supply Pipes
Water-supply pipes are easier to run than DWVs
because they’re smaller and don’t need to slope.
When filling the dWV system for
Metal supply pipes should be bonded to the
testing, use a double dynamiter to
house’s electrical grounding system (see p. 266).
block the combo fitting at the base of
the main drain.
run supply pipes to fixtures once hot and cold
trunk lines are connected. Run 3⁄4-in. trunk lines,
using 1⁄2-in. pipe for branch lines serving two
fixtures or fewer. Individual supply risers for
Testing plugs. Clockwise, from
toilets and lavatories are often 3⁄8 in. You save
bottom: 11⁄2-in. test plug, 3-in. test
some money by using smaller-diameter pipes,
plug, 4-in. test plug, and “jim cap.”
but the main reason to reduce pipe diameter is
The first three plugs are inserted into
to ensure adequate water pressure when several
pipes and expand via a wing nut; the
fixtures are used simultaneously. Reducing tees,
jim cap slips over the outside of a
pipe and tightens with a band clamp.
such as the 3⁄4 by 1⁄2 shown in the bottom photo
on p. 323, provide a 1⁄2-in. branch takeoff from a
3⁄4-in. trunk line.
Support horizontal runs of copper supply pipe
at least every 6 ft., but if pipes run perpendicular
to joists, plumbers usually secure the pipe every
second or third joist. Support vertical runs of
copper at every floor or every 10 ft., whichever is
less. Support horizontal runs of CPVC supply
pipe every 3 ft.; vertical runs should be supported
every 10 ft., with clamps or plumber’s strap
attached to blocking. Support PEX tubing every
32 in. on horizontal runs and every 10 ft. on verti-
cal runs (with midstory guides).
Keep hot and cold pipes apart at least 6 in.
They should never touch. To conserve energy,
reduce utility bills, and get hot water sooner at
fixtures, install closed-cell foam insulation
344 Chapter 12
sleeves on hot-water pipes. As noted earlier,
water-supply stub-outs should protrude at l
east
6 in. into living space. To hold stub-outs in place,
solder them to perforated copper straps nailed or
screwed to studs.
Code requires shutoff valves for every fixture
riser. Supply pipes to outdoor spigots or unheated
rooms should have shutoff valves and unions
within the main basement so pipes can be
drained. Install water-hammer arrestors on
branch lines to appliances such as washers or
dishwashers, whose solenoid valves stop water
flow so abruptly that pipes vibrate and bang
against the framing.
To test the supply system before installing dry-
wall, solder caps onto fixture stub-outs and turn
on the water. (If you’re installing CPVC supply,
cement caps onto stub-outs.) If there are no
leaks, install steel nail-protection plates over any
pipes that lie within 11⁄4 in. of a stud edge, or use
steel stud shoes over notched studs. Then install
finish surfaces.
Water-supply pipe supports. Clockwise from upper left: two acousto-Plumb® clamps (which
reduce pipe noise by cushioning vibrations), a copper pipe strap, a 3⁄4-in. by 6-in. plastic-coated
Instal ing Fixtures
wire hook, two plastic suspension clamps, and a felt-lined J-clamp.
after running dWV branch drains to
Before you can install a new fixture, there’s often
fixtures, install supply-pipe
an old one to remove. If it’s necessary to shut off
assemblies and solder stub-outs to
water to several fixtures during installation, cap-
perforated strap.
ping disconnected pipes will allow you to turn
the water back on even if all the new fixtures
haven’t been installed.
DIsConneCTIng FIxTures
Before disconnecting supply pipes, shut off the
S a f e T y a l e R T
valves that control them. As mentioned, code
requires a shutoff valve on each fixture riser, but
older systems may have only a main valve that
Dielectric unions have insu-
shuts off water to the whole house. After shutting
lators inside that will not con-
off the controlling valve, open the faucets to
duct electricity. If your electrical
drain the water.
system is grounded to the water
main and you install a dielectric
Lavatory or sink supply pipes may have unions
union to join copper pipe to a
that can be disconnected using two pipe wrenches.
galvanized steel service pipe,
Otherwise, water-supply nuts (water nuts) will
for example, install a bonding
connect the tops of supply risers to threaded
jumper to ensure continuous
faucet stems on the underside of the basin. To
grounding.
loosen water nuts, use a basin wrench, which has
a shaft 10 in. to 17 in. long and spring-loaded
jaws set at a right angle to the shaft. If the lav is
wear a respirator to avoid inhaling smoke from
old and you intend to reinstall it, save the water
gaskets and such.
nuts because the threaded faucet stems may be
Once you’ve disconnected the drain and sup-
nonstandard.
ply pipes, lift the lav/sink off its wall hanger, ped-
To disconnect a fixture’s drainpipe, use two
estal, or cabinet base and set it aside. An old cast-
pipe wrenches to loosen the slip-nut coupling of
iron lav can be quite heavy, so lift it with the aid
the P-trap. If older galvanized couplings have
of a helper. Place a plastic bag over the drainpipe
seized up, heat them with a propylene gas torch
stub, and secure it with a rubber band to keep
and tap them lightly with a hammer to free the
sewer gases at bay. Disconnect fittings carefully
joint. Then try again with wrenches. Be sure to
if you want to reuse them.
plumbing
345
To remove a toilet, shut off the water by shut-
ting the chrome fixture stop near the base of the
setting a pedestal sink
unit. Flush the toilet and remove the remaining
water with a cup or an inexpensive plastic hand
Installing a pedestal sink takes planning, a lot of adjusting, and two people. For
pump. Disconnect the tank from the toilet bowl
starters, determine well in advance the height of the 2x blocking needed to anchor
by loosening the bolts that hold the sections
the sink so you can cut that board into stud walls well before the drywall goes up.
together. If the tank is wall hung, use a wide-
preattach the sink’s hardware before mounting it on the pedestal. next, level the
jawed spud wrench to loosen the slip nut between
pedestal base, shimming it as needed. Ribbed plastic shims (also called ribbed sta-
the tank and the bowl. The toilet bowl is fastened
bility wedges) work well for this task because their ribs keep them from slipping,
to the floor by two bolts that rise from the floor
even if it’s necessary to stack wedges on a badly out-of-level floor. once the base is
flange; unscrew the nuts capping the bolts on
level, set the sink atop it and check it for level in two directions—front to back and
both sides of the bowl. Rock the toilet bowl
side to side—using two torpedo levels, as shown in the left photo on p. 348.
slightly to break the wax seal on the bottom.
Chances are, you’ll need to reset the sink several times to get it level and stable
Then lift up the bowl and immediately block the
because sinks and pedestals are often not perfectly mated.
drainpipe by stuffing it with a plastic bag con-
once you’re pleased with the sink’s placement, use a pencil to mark the locations
taining wadded-up newspapers.
of the lag-screw holes on the wall. remove the sink, predrill pilot holes, replace the
Tub drain assemblies may be hidden in an end
sink, check for level again, and line up the pilot holes with the mounting holes in
wall or they may exit into a hole cut into the sub-
the back of the sink. Before inserting the lag screws, however, lift the sink slightly
floor under the drain. The drain and overflow
so a helper can slide out the pedestal and attach the drainpipes. That done, slide
assembly is usually held together with slip cou-
back the pedestal and reset the sink, then tighten the washered lag screws to secure
plings, so use a pipe wrench to loosen them. If
the sink. But don’t overtighten or you’ll crack the porcelain. attach the supply risers
the drain is a solid piece, cut through it. Supply
top and bottom, test for leaks, and you’re done.
pipes may be joined with unions or they may be
soldered; it’s easiest just to cut through supply
risers. With those pipes disconnected, you can
move the tub.
It’s much easier to attach hardware
If it’s a standard tub (rather than a freestand-
to the underside of a sink before
ing tub), you may need to cut into the finish sur-
mounting it. Here, the plumber
faces at least
1 in. above the tub to expose the tub
uses flexible stainless-steel lines to
lip, which is often nailed to studs. If you’re dis-
connect hot and cold faucet valves
carding the tub and don’t care about chipping its
to the spout inlet. The threaded
enamel, use a cat’s paw to pull the nails. If the
bottom of each faucet tee—one is
visible, at right—receives a 3⁄8-in.
tub is too heavy or tightly fit to slide out of its
water-supply riser and a water nut
alcove, you may need to cut the studs of the end
that holds it tight.
wall so you can slide the tub out.
InsTallIng lavaTory
BasIns anD kITChen sInks
Lavatory basins are supported by pedestals, cabi-
apply plumber’s putty or silicone
net counters, legs, wall-mounted brackets, or a
under the flange of the drain
combination of these, whereas kitchen sinks
tailpiece, insert it into the drain
almost always attach to base cabinet countertops.
hole, then use sliding-jaw pliers to
Counter-mounted lavs or sinks are particularly
tighten the locknut on the underside
of the basin.
popular because of the storage space underneath.
Preassemble the hardware. Before mounting a
sink or lav, attach its hardware, including fau-
P R O T I P
cets, spout, and the drain tailpiece. These connec-
tions are easier to make when the fixture is
when connecting supply
upside down before installation. Insert the
lines to fixtures, code requires
threaded faucet stems through predrilled holes
hot on the left, cold on the right.
in the sink or lav body, and tighten the washered
when your eyes are shut tight
nuts on the underside. Many manufacturers
against soapsuds and you’re fum-
supply a rubber gasket, but when that’s lacking,
bling for a faucet, it’s reassuring
spread a generous layer of plumber’s putty
to know which spigot is which.
between the metal and the porcelain. Don’t over-
tighten. Once the faucets are secure, you can
346 Chapter 12
P R O T I P
zzzzzz lavatory assembly
an old cast-iron tub can
weigh hundreds of pounds, so
Spout
get help removing it. If the tub
is a standard type, be especially
careful that it does not drop sud-
denly when you pull the tub lip
Renovation 4th Edition Page 80