Wall position in almost all cases. A wall-position drain keeps the slope shallow, takes the drain out of the walking area, and makes waterproofing simpler than a centre channel — which needs water to fall toward the middle from both sides.
Comparison
| Wall position | Centre position | |
|---|---|---|
| Floor falls | One direction only | Two directions, meeting at the channel |
| Slope | Generally shallower | Steeper or more complex |
| Walking area | Drain is out of the way | Drain is where you stand |
| Waterproofing | Single detail at the wall-floor junction | Detail in the middle of the floor |
| Tiling | Tile runs to the wall line | Tile falls to the channel from two sides |
| Waterproofing risk | Lower | Higher — more complex junction |
When a centre drain is justified
- Open showers served from both sides — where the shower can be entered from two directions, a wall drain may not collect water from both halves efficiently.
- Structural constraints — the outlet route may only be available in the middle of the floor.
- Existing pipework — in renovations, the existing outlet position may dictate the drain location.
- Very large showers — where a single wall drain would require too much fall across the floor, two opposed or a centre channel may suit better.
Practical considerations
- With a wall-position drain, confirm the wall is straight — the channel runs the full length of the opening and any bow shows.
- Waterproofing at the wall-floor junction is a three-way detail; a drain with an integrated flange simplifies it.
- For barrier-free showers, wall position allows the shallowest possible fall.