Parts of a Shower Drain – Labeled Tile Floor Section

All 12 parts on the diagram

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Layers of the floor 6

Tile It is laid sloping toward the drain.
Mortar bed It lies on top of the pan liner.
Pan liner (membrane) Runs under the mortar bed, up the walls and over the curb.
Sloped subbase It falls a quarter inch per foot. Water on the liner then runs to the weep holes.
Subfloor Wood or concrete. The drain base rests on top of it.
Curb Also called the dam or threshold. The liner goes up and over it.

Drain and pipe 6

Drain pipe The drain base is joined to the top of it.
P-trap It stays full of water. That keeps sewer gas out of the room.
Strainer (grate) It stands on a threaded barrel. Its height can then be set level with the tile.
Clamping ring (collar) Its bolts screw into the drain base. They squeeze the liner between the two.
Weep holes Water that reaches the liner drains through them into the pipe.
Drain base (body) Its wide flange rests on the subfloor. The liner lies on the flange.

How this list was compiled: Every name checked on 2026-09-30, a name kept only where two independent sources use it: the Ceramic Tile Institute of America's standard specification for tile lined shower receptors (https://archive.org/details/gov.law.ctioa.r8-103-62.1969); the International Residential Code, 2012 edition, section P2709 (https://archive.org/details/gov.law.icc.irc.2012); a drain maker's pan liner how-to, clamping drain submittal and no-caulk drain instructions, read in Internet Archive copies (the first is https://web.archive.org/web/20090902182957/http://www.oatey.com:80/apps/catalog/instance_assets/assets/How_to_Use/ShowerPanLiner.pdf); a second maker's drainage catalog; and Wikipedia, Trap (plumbing), for the P-trap. No maker is named on the page. Licence: own work

The drawing: Drawn for this site on 2026-09-30 from plain geometry; a schematic of no maker's drain, nothing traced. Licence: own work

How it works

The parts of a shower drain make sense only with the floor round them, so the first drawing cuts through a whole tiled shower floor. The second enlarges the drain: strainer, clamping ring, weep holes and drain base.

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The floor, top to bottom

Tile sits on a mortar bed. Under the bed is the pan liner, the waterproof layer, which runs up the walls and over the curb. The liner lies on a sloped subbase, so water that reaches it runs toward the drain. Under that is the subfloor.

The drain, in two halves

The drain base sits on the subfloor with the liner on its flange. The clamping ring bolts down on top and pins the liner in place. Weep holes at the foot of the ring let water off the liner into the drain pipe. The strainer screws into the ring from above, and the P-trap is under the floor.

A drain for a one-piece shower base has no clamping ring: a locking ring and washers seal it to the base instead.
Pea gravel is often packed round the weep holes so the mortar cannot block them.

Questions and answers

What are the parts of a shower drain?

A drain for a tiled shower has a strainer on top, a clamping ring under it, weep holes at the foot of the ring and a drain base joined to the drain pipe. Below the floor the pipe runs through a P-trap.

What are weep holes in a shower drain?

Small openings in the drain at the level of the pan liner. Water that reaches the liner runs down its slope and out through the weep holes into the drain.

What does the clamping ring on a shower drain do?

It bolts to the drain base with the pan liner sandwiched between them, which makes a watertight joint between the liner and the drain. The strainer's threaded barrel then screws into the middle of the ring.

What is under a tiled shower floor?

From the top down: tile, a mortar bed, the pan liner, a sloped subbase and the subfloor. The pan liner is the waterproof layer, and the drain is clamped to it.