Ch4 of the UPC states:
When the construction of on-site built-up
shower receptors is permitted by the Authority
Having Jurisdiction, one of the following means shall
be employed:
(1) Shower receptors built directly on the
ground:
Shower receptors built directly on the ground
shall be watertight and shall be constructed
from approved type dense, nonabsorbent and
non-corrosive materials. Each such receptor
shall be adequately reinforced, shall be
provided with an approved flanged floor
drain designed to make a watertight joint in
the floor, and shall have smooth, impervious,
and durable surfaces.
(2) Shower receptors built above ground:
When shower receptors are built above
ground, the sub-floor and rough side of
walls to a height of not less than three (3)
inches (76 mm) above the top of the finished
dam or threshold shall be first lined with
sheet plastic,* lead,* or copper* or shall be
lined with other durable and watertight
materials.
All lining materials shall be pitched onequarter
(1/4) inch per foot (20.9 mm/m) to weep
holes in the sub-drain of a smooth and solidly
formed sub-base. All such lining materials shall
extend upward on the rough jambs of the
shower opening to a point no less than three (3)
inches (76 mm) above the top of the finished
dam or threshold and shall extend outward over
the top of the rough threshold and be turned
over and fastened on the outside face of both the
rough threshold and the jambs.