I have a basement tiled shower that had previously leaked (before I
owned it) into the wood framing. The studs and plywood (yes, tiles were
directly attached to plywood) was mostly rotted near the base.
I've since removed the rotted wood, treated any that is still in okay
condition. Now my dilema is how to create a proper shower pan that
won't leak. The previous never had the membrane that I've seen for most
I had a plumber over to look at it and he suggested there's no need for
a shower pan per se because it's in the basement. Instead of framing
the bottom with wood, and installing the membrane (chloraloy), he
suggested to just surround the base with a concrete 'curb', apply some
kinda water resistant coating.
Does this make sense?
To properly build a custom shower you need first to build and shower curb
and pre-slope base that would slope 1/4 in per foot from walls to the drain.
You need to use special shower drain that consist of two parts, one screws
into another. This type of drain also has weeping holes intended to collect
water from pre-slope base into the drain. Pre-slope base should be flush
with lower part of the drain. You put shower pan liner on the pre-slope base
ensuring that it goes up on walls at least 12 in, goes fully around shower
curb including outside side. You never cut the liner on corners. In corners
where shower walls meet you fold the liner, on outside corners where walls
meet with curb you use special outside corners manufactured by the same
manufacturer as your liner. I used Qatey PVC liner but CPE will work as
well. If you need to glue two parts of the line as your shower is larger
that the liner width you use special adhesive ensuring that two glued parts
overlap at least 3 in. You only staple the liner at very top on the walls,
you do not staple anywhere else. You put the liner over lower drain part and
screw up the upper part. Then you accurately cut the liner for the drain
hole. Then you unscrew the upper part and put silicon caulk between lower
drain part and the liner. Now you can build upper part of shower base. Some
people suggest using wire mesh for both lower and upper part of the shower
base. I used 5-1 ratio of sand to Portland cement with no wire mesh. To
build a shower curb you use different type of mix similar to one used to lay
down bricks that has lime. It is sold premix so you can just add water. Last
moment. After you built lower part of the shower base and put the liner up.
Plug the drain and fill it with water till the curb. Leave it for 24 hours.
If you see that no leakage occurred you base is waterproofed if water leaked
you need to find the leak in the liner and glue a patch over the hole that
causes the leak. Repeat test again until you find no leaks.
No sense at all -- unless you really want to live with the resulting leaks,
moisture, and mold problems. You would be amazed at how much water can
leak right through concrete.
Build or buy a proper waterproof shower pan.
Thanks. I've previously researched the floating mortar bed type with
the membrane and know what would be done in that case. My question was
more why I couldn't get away with using concrete as it would prevent me
from having to tamper with my existing shower drain (dig it up, try to
attach a new drain, etc..).
Murray suggested mold and leaks. This plumber suggested coating the
concrete with a water resistant 'paint' of sorts (don't remember the
name). I should be able to test for leaks by filling it up afterwards.
I think his point was that it's a lot of work to tear up the drain and
any leaks into the ground are not a problem if it's in the basement,
only leaks out the sides. If the concrete could adequately seal the
edges (much like the curb would do---I have a concrete curb as it is
already) then why deal with the drain?
There are a variety of paint on membranes for under tile installations. Red
Guard made by Custom Building products is available from Home Depot. If you
go this route you want to waterproof the entire shower, not just the floor.
A typical shower pan allows for any moisture that wicks through the grout to
find it's way to the pan and down the drain. By going the paint on route you
would be preventing this. You need to make sure that no water penetrates the
Thanks. So to make sure I understand, you're suggesting I can use a
concrete 'box' as my shower pan provided I coat the concrete, before
applying the thinset, with this paint (e.g. Red Guard).
I presume you mean to paint it on all the concrete, not just the floor
as opposed to the whole shower. I will be using concrete backerboard
for the walls so it makes no sense to put this paint on the backerboard
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