Installing the Shower Pan Liner
A shower pan is a waterproofing system that channels water
into a drainage system. Since buildings move, shower pans must
be able to accommodate movement. In the old days, lead or
copper sheeting and hot-mopped shower pans were common, though
they were difficult to work with and prone to leaks. For the
past 20 years, I’ve been using chlorinated polyethylene
(CPE) sheet membrane to fabricate pan liners for showers,
sunken tubs, fountains, and other wet tile installations.
Available from the Noble Co. (614 Monroe St., Grand Haven, MI
49417; 800/878-5788), CPE membrane, called Chloraloy, comes in
4-, 5-, and 6-foot-wide rolls, and can be bonded to itself to
make shower pans of any size.
I install blocking between the studs around the entire
perimeter of the pan area, making sure the blocking extends at
least 1 inch above the upturned sides of the pan, and that all
fasteners are countersunk or flush. Local codes will vary, but
I typically make the sides 8 to 9 inches high.
I make a sketch of the shower floor area and the upturns
where the membrane meets any walls or curbs. I unroll the
membrane in an open area, reproduce the sketch on the CPE
membrane, and cut it to size. Next, I crease the corners, fold
up the membrane, and place it on the shower floor for a dry
After cutting the membrane material to size
(top left), the curb edges are folded over (top right)
and the entire sheet is rolled up (left) and placed on
the sloping mortar subfloor.
When I’m sure of the fit, I refold and remove the
membrane, loosely screw the membrane clamping bolts (bolts that
clamp the two halves of the drain together) into the lower half
of the drain, and run a bead of rubber sealant around the lower
drain flange. I use Noble’s proprietary sealant,
NobleSealant 150, when working with its CPE membrane.
I then reposition the bundled liner over the shower floor
and lower it into place. After creasing and folding the excess
corner material, I staple it flat to the wall blocking, holding
all staples to within an inch of the top edge. I apply sealant
between the layers of the corner folds to hold the material
tight against the wall blocking.
NobleSealant 150 is applied to the folded inside corners
(left) before stapling them in place (right).
On large installations, I install the membrane in several
smaller sections, then use NobleSealant 150 to join the pieces