Shower Pan Test
How you can test your shower pan
for leaks!
by D.  Koen, Feb. 2007
There are many ways a shower can leak and a shower pan leak is
probably the most costly. It makes good sense then to determine if
the leak you are getting from your shower stall is actually your pan.

In the 30 years that I have been repairing leaking shower pans in
Dallas and Collin counties,  I have been asked to determine if a
shower pan was actually leaking or not after a homeowner had
another contractor or home inspector look at it and concluded it was
the pan that was leaking. Many times they were correct and many
times they were wrong.

Before you hire a contractor to repair your leaking shower pan, why
not test it to be sure! It doesn't take much time or effort, but you must
do it on a day when you will be home all day. See warning below!
Here are the materials you will need;
a) a large bucket
b) duct tape
c) tape measure
d) flashlight

A plumber would use a 2" inflatable test ball for this test, but I don't
recommend it for the homeowner since you are probably only going
to test once or twice in your lifetime anyway. Duct tape will do the job
cheaply and effectively.

WARNING: Do this shower pan test ONLY on a day when you can be
there for the entire duration of the test. Otherwise, you risk a
discharge of water that could ruin adjacient flooring etc. Stop the test
as soon as you see water outside of your shower!

Make sure your shower floor is dry around the drain and place duct
tape over the drain. Much larger than the diameter of the drain,
about the size of a paper plate. Press it down firmly to make it as
watertight as possible. DO NOT  I repeat DO NOT use water from
your shower faucet for this test. Use water from an adjacient bathtub,
a kitchen sink, or another bathroom. We want to exclude the
possibility that your shower faucets are the problem or cracks in the
shower walls.

Once you have a bucket of water(1/2 to 2/3rds full is best), gently
pour it into the bottom of your shower floor until the floor is covered
to a water depth of no more than 1 inch. That's right! I said one inch,
and that wasn't a misprint. Many people will tell you to fill the water up
1 inch below the top of the curb and this is wrong. The shower pan
doesn't come up that high in 99% of the showers. The real height of
the pan on the top of the curb is 4.5 inches. That is measured from
the floor outside the shower next to the curb up the outside of the
curb tile. A standard curb is made from three 2" x 4" studs(3 x 1.5" =
4.5"). The pan is laid over the studs, then a layer of concrete is
floated on top of it. So, a finished curb maybe 6- 7 inches tall but the
pan height is much lower and you must not fill the water over that
level. One inch of water will do fine for this test. Measure the height
of the water near the curb where you can easily read it.

What you are going to look for is a discharge of water around the
perimeter of your shower. If you are on a  pier & beam foundation,
you will need to look for the discharge of water under the shower
area.  Find your access door that leads under your house(for those
without a basement). Using your flashlight, looks for signs of water
dripping under your shower. On a slab foundation the water will
spread in the path of least resistance. If you have ceramic tile next to
your shower curb, the water may go around to an adjacient closet or
room. You may need to pull back any carpet that's next to your
shower and look under it for leaks. So, look at all sections of floor
next to shower for water leaks.

You will need to test your shower pan for at least 8 hours. Some
leaks like nail holes take a long time to show up on a test. Your job is
to check for leaks around your shower every now and then. If the
water level goes down, and it may, then add more water to the
shower floor until you are back to the original water test level of 1

If you see a water discharge(or leak), then pull the duct tape off of
the drain. The test is over! Your shower pan is positively leaking!
The leak may be in the bottom of the pan, or at the seal between the
pan and drain. Either way the pan must be replaced in my opinion.

If you don't see a water leak from this test, it doesn't mean your
shower pan isn't leaking. This test ONLY tests the shower pan in the
bottom of your shower. It doesn't test your shower pan where it
covers your shower curb or seat. It is very common for a shower pan
to leak in these areas, especially where the curb meets the wall.

Until a few years ago, curbs were constructed without pan corners at
each end. If your shower curb doesn't have pan corners, you will see
water damage or water leaks at both ends of the curb. Sheetrock
may be wet or stained. Paint on base moulding will turn moldy or
discolored. Linoleum floor next to your shower may be discolored
near the ends of the shower curb and no where else! So look for
these common signs.

The shower pan could be leaking on your shower seat if the pan was
installed improperly and your shower pan test proved negative. It
may be possible to tear out this area only to repair the leak. In some
cases, you may need to replace the whole shower pan.

Some other possibilities as the cause for a shower leak other than
your shower pan is your shower door or door system. Shower doors
aren't submarine doors. They don't positively keep water from
escaping the shower. Check the door seal at the bottom of the door
for leaks. Have someone take a shower and direct the water over to
your door to see if it is containing the water. Look also underneath
your shower door to see if there is an open door track( on a sliding
door system) or a closed track. Either one should be caulked at the
ends of the track so water doesn't discharge out the ends of the
track. Both of these are fairly common sources of shower leaks.

Another possibility for a shower leak is your shower faucet. The
faucet could be leaking behind the wall at either a pipe connection or
solder joint. This can easily be tested by removing the shower head
on the shower neck and screwing on a galvanized 1/2" pipe cap
sealed with teflon tape or pipe joint compound. Once this is in place,
no water can come out of the shower neck obviously.This puts water
pressure on the faucet connections and joints behind the wall. Look
for a leak on the floor adjacient to the shower faucet wall. Do the test
for at least 30 minutes.

Water can also leak behind your shower faucet handle escucheons
where they meet the wall. Water can hit your body and deflect back
against your faucet wall, thus dripping behind the metal handle plate
covers. Why not just seal around these covers with clear silicon to
remove this possibility of a leak. The out of pocket cost for this repair
is hardly anything, so do it!

Another quite common cause of shower stall leaks are cracks in the
major corners of your shower, primarily the vertical corners. Caulk
these corners with a high grade silicon. I always start the caulk line at
the top of the corner and gun the silicon out at a slow but even line,
approximately 3/16"-1/4" wide, then stop the caulk halfway. I then
move the caulk gun tip to the bottom of the corner and caulk up to
the halfway point where I left off. To assure a great seal that also
looks nice, I press my middle finger tip against the caulk at an angle
of approximately 30 degrees using the same method I used when I
gunned the caulk. Top  to middle, then bottom to middle. Any
mistakes can be corrected with denatured alcohol and a handful of

Cracks in the corners of shower stalls can allow water to flow through
and drip down the backside of your shower pan, so, caulk all major
shower corners.

A shower leak of any kind is a serious problem. It's not something
you want to put off. Water leaks can cause mildew, wood rot and
attract insects like termites. So, the sooner you address the problem
the cheaper will be your solution.

Fiberglass shower pan: Some showers are constructed with fiber-
glass one-piece floors. These act as both your floor and your shower
pan. This type of pan can develope cracks in them over time. Some
of which you can see. Test this shower pan exactly the same way with
duct tape covering the shower drain and look for a water discharge
somewhere around the perimeter of the floor.

Since there are no weep holes on this type of pan you can also
measure the height of the water inside the shower pan and look for
any changes in depth during the test.

This is a very simple test that almost anyone can do and it will save
you some money. Good luck!

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