Match a Shower Drain Connection by Base, Pipe and Seal

A replacement shower drain must match both the shower base or waterproofing system and the waste-pipe connection. A matching cover diameter—or a listing that says “2-inch drain”—does not settle either question.

Before ordering, photograph the drain with its cover removed, record any brand or molded number, and identify the pipe material. If accessible, photograph the underside too. Do not loosen the drain body just to identify it: first establish how it seals and whether you can reach the connections needed for reassembly.

Start with the shower base

Distinguish a factory-waterproof shower base from a tiled, waterproofed assembly before comparing outlets:

• Preformed waterproof shower base: Oatey’s 140/101 PNC no-caulk drains are designed for preformed bases. Their instructions explicitly exclude tiled floors requiring a shower pan liner. A locking ring and washers secure the body to the base; a separate compression gasket seals around the waste pipe. See the Oatey installation instructions.
• Tiled shower: Identify the waterproofing system, not just the tile or grate—even if the tile sits on a prefabricated tray. A traditional liner/clamping-ring assembly differs from a surface-bonded membrane drain. For example, KERDI-DRAIN has a bonding flange that connects to the waterproofing membrane at the top of the assembly; the standard drain is not intended for traditional waterproofing beneath the mortar bed. See Schluter’s technical data sheet.

Stop if the waterproofing connection is unknown. Replacing a tiled shower’s drain body is not simply changing the visible grate.

Identify how the drain connects to the pipe

These are pipe-connection types, not interchangeable shower-floor designs.

Connection	Identification clue	What must match
No-caulk compression	Rubber gasket around the pipe, compressed by a tightening ring inside the drain	Drain series, pipe size and material, correct gasket, and specified pipe height
Solvent-weld	Plastic outlet/socket intended to be cemented to plastic pipe	Outlet size, pipe and drain material, insertion geometry, and specified cement
No-hub/mechanical coupling	Outlet joined to the pipe with a separate mechanical coupling	Both mating diameters, materials, approved coupling, and installation access
Threaded outlet	Actual pipe threads at the outlet	Matching thread specification and the manufacturer’s sealing method

Oatey documents the compression-gasket connection. Schluter documents solvent-weld plastic outlets, mechanical no-hub outlets and threaded outlets within its KERDI-DRAIN range.

Do not mistake a threaded locking ring or grate-height adjustment for a threaded waste-pipe connection. Identify the outlet, not merely a thread visible from above.

Record the dimensions that decide compatibility

Use this as your ordering checklist:

1. Drain brand, series and part number: Match against the manufacturer’s drawing or instructions.
2. Pipe material and marked nominal size: Also measure the outside diameter where accessible and compare it with the specified connection.
3. Base opening and thickness: For a preformed waterproof base, compare these with the drain’s mounting dimensions.
4. Pipe height and alignment: Record the pipe’s position relative to the reference surface named in the instructions—not a guessed distance below the cover.
5. Outlet direction and access: Confirm vertical versus horizontal outlet and whether installation requires access beneath the base.
6. Replacement scope: Decide whether you need a cover, pipe gasket, base sealing washer, coupling or complete drain body.

Pipe material matters even when the nominal size matches. For example, PACE Supply lists Oatey 42158 specifically for 2-inch copper DWV pipe in a No-Calk shower drain. That is a material-specific gasket, not a universal 2-inch seal. Check the drain series before using the 42158 listing as an ordering match.

For a cemented KERDI-DRAIN connection, Schluter specifies ABS-to-ABS or PVC-to-PVC with the respective cement. Do not directly cement that drain to a waste pipe of the other plastic; follow its ABS/PVC compatibility guidance.

Seal the correct joint—and test before closing up

“No-caulk” describes the pipe seal, not every joint in the drain. Oatey’s instructions still require sealant beneath the flange where it meets the preformed base. They specify suitable plumber’s putty for applicable materials, but 100% silicone instead of any putty for an ABS drain body. Check the base maker’s requirements as well. The rubber pipe gasket is a separate seal; silicone is not a substitute for the correct gasket.

Pipe height is also model-specific. For Oatey’s 140/101 PNC installation, the pipe finishes ¾ inch below the top of the no-caulk barrel flange. The pipe must be cut square, deburred and chamfered before fitting the gasket. Do not transfer that dimension to another drain. These details appear in the Oatey product instructions.

Follow the exact drain/base testing procedure and any local requirements before concealing connections or setting tile. For KERDI, Schluter specifies waiting at least 24 hours after membrane installation before flood testing in its technical data sheet.

Stop and get a plumber’s assessment if the pipe is too short, off-center or damaged; the base moves; or reaching the connection would disturb unknown waterproofing. Those conditions need more than a replacement seal ordered by appearance.