How it connects
Liner is laid over the drain base flange (often over a bead of sealant), holes cut for the bolts, then the clamping ring is bolted down (typically 3-4 bolts), compressing the membrane between ring and flange to seal it; weep holes pass water.
Male and female halves
No male/female; a flange-and-ring sandwich. The drain base flange is the lower half, the bolted clamping ring the upper half; the membrane is clamped between them.
Usually connects to
- Compatible PVC/CPE sheet liner or other specified waterproofing sheet/liquid membrane
- Matching drain-body flange and clamping ring
- Matching adjustable threaded drain barrel/strainer
Common sizes
- Drain outlets include 2, 3 or 2 × 3 in; ring diameters are product-specific, commonly about 5–7 in (130–180 mm).
- One example has about 132 mm OD, 65 mm ID, 1 mm liner and four bolts; typical rings use 3–4 bolts.
Where it is used
mortar-bed shower constructionresidential and commercial bathroomstiled shower pans with mortar bedresidential plumbingFloor drainsShower-pan waterproofing
Variations
- reversible clamping ring
- ring with threaded adjustable barrel
- square/linear drain tops on clamping-ring bodies
- cast iron/brass commercial versions
- PVC or ABS drain bodies
- cast iron / brass clamping drains
How to recognise it
Wide flat round flange atop the drain body with 3-4 bolt holes or bolts, a separate matching ring above it, a threaded central bore for the strainer barrel and small weep holes in the ring.
Often confused with
| Confused with | How to tell them apart |
|---|---|
| Bonding-flange drain (e.g. Schluter Kerdi drain) | Bonding-flange drains have a fleece-covered flange the membrane is thinset-bonded to, with no bolted ring. |
| Shower drain pipe socket connection | The socket/inside-fit end below is the pipe joint; the clamp is the wide flat flange at the top. |
| Compression/gasket drain for preformed shower base | Those seal a fiberglass/acrylic base with a rubber gasket and locknut, not a bolted ring over a flexible liner. |
| Integrated bonding-flange drain | A bonding flange provides a surface for bonding the membrane; a clamping-ring drain mechanically captures it with a separate bolted ring. |
| Drain pipe socket or spigot | The membrane interface is the broad ring around the drain opening; the pipe connection is the separate outlet below. |
Also called
clamp ring collarshower pan liner clampdivided-flange draintwo-piece shower drain clamping ringshower pan liner clamping ringthree-piece shower drain liner clampmembrane clamping flange; Membrane clamping ring; Clamping-ring drain flangeWaterproofing membrane clamp
Good to know
Not a pipe joint; it's a membrane-sealing flange. The sample part's 2 in socket / 3 in inside-fit end is a separate port.
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