Curbless Tile Shower Linear Drain Sizing | EZ Able

Curbless Tile Shower with a Linear Drain: Sizing and Install FAQ

Quick answer

All QuickDrain systems (ShowerLine, ProLine and WALLdrain) work in a curbless shower. Measure the opening wallboard to wallboard. For ShowerLine or ProLine, choose the drain just smaller than the opening and use the trough extensions to reach wall to wall. For WALLdrain, choose the next size larger and cut it to fit.

How to size the drain

SystemTypeHow to choose the size
ShowerLineLinearDrain just smaller than the opening; trough extensions go wall to wall
ProLineLinearDrain just smaller than the opening; trough extensions go wall to wall
WALLdrainIn-wall linearNext size larger than the opening; cut to fit wallboard to wallboard
SquareDrainCenter pointPan larger than the shower footprint; cut the pan to size

The rough opening (RO) is measured from wallboard to wallboard.

Plan the flow rate

Drain locationDesign flow per outlet
Curbless, drain at the threshold (entry)5 GPM
Curbless, drain at the back wall10 GPM
Any curbed shower10 GPM

Install: ShowerLine with a curbless entry and back-wall drain

  1. Cut and remove the 3/4" OSB subfloor within the shower footprint without damaging the joists below.
  2. Add subfloor blocking so you can drop in 3/4" OSB between the joists, and secure it.
  3. Joists perpendicular to the drain: check your local building code before modifying joists to fit the internally sloped drain trough.
  4. Joists parallel to the drain: block about 10" on center to support the drain trough and the subfloor next to the drain flange.
  5. If you use PET ADA slopes, set them flush against the drain flange so they end at the entry/threshold.
  6. Check finished floor elevations to see if you need extra substrate for buildup.

Why go curbless with tile

  • Universal design: a roll-in shower makes the shower accessible in line with the Americans with Disabilities Act.
  • Easier cleaning: larger-format tile means fewer grout lines and joints to maintain.
  • Flooring options: nearly any finish or flooring material suitable for showers.

Good to know

Joist work is code-dependent. Always confirm with your local building department before cutting or modifying floor joists.

Common questions

Which QuickDrain systems work in a curbless shower?

All of them: ShowerLine, ProLine and WALLdrain.

Do I use the rough or finished opening to size the drain?

Measure wallboard to wallboard. Pick ShowerLine or ProLine just smaller than that and extend to the walls; pick WALLdrain one size larger and cut to fit.

What flow rate should I plan for?

5 GPM per outlet for a curbless drain at the threshold; 10 GPM per outlet for a curbless back-wall drain or any curbed shower.

Related help

Need a hand?

Call us at 877-392-2531, Monday–Friday, 9–5 Eastern. You can also open a support ticket or chat with Abby on ezable.com.