What Is an Italian Shower, and How Do You Build a Curbless Shower?

It looks simple. But there is no curb to hold the water back, so the shower floor has to do all the work. This guide explains the parts you choose, the questions to settle before you buy, and where FloorBox products fit.

What is an Italian shower?

An Italian shower is a walk-in shower with no curb. A curb is the low step that keeps water inside a regular shower. In a curbless shower, the shower floor sits at the same level as the rest of the bathroom floor.

Without a curb, two things keep the water in the shower: the slope of the shower floor, and the drain. Schluter's curbless shower brochure (you can download it from the Schluter KERDI-SHOWER-R shower ramp page) adds an important point. With no curb, the wet area and the dry area are not clearly separated. So the whole bathroom floor needs protection against water, not just the shower.

What are the parts of a curbless shower floor?

You choose four things:

• A sloped shower pan. It's also called a shower base. It tilts the floor toward the drain. A factory-made pan comes with the slope already built in.
• A drain. Either a drain in the centre of the floor, or a long, narrow linear drain along one side.
• Waterproofing. A membrane is a thin waterproof sheet. It goes over the pan, the walls and the seam where the shower meets the bathroom floor.
• The edge. How you get the shower floor and the bathroom floor to the same height.

Still deciding between a curb and no curb? Shower Base or Shower Pan explains the basic choices.

How does a one-piece curbless shower pan work?

The Prova Pan-Multi sloped shower pan, 60" x 60" is made for this job. Its page says:

• It is "a one pan solution for curbed or curbless shower installations."
• Prova's current data sheet (revised December 2021) lists a thickness of 7/8".
• It "replaces the need for a mortar base." A mortar base is a thick, sloped bed of cement that an installer builds by hand.
• It is made of lightweight expanded polystyrene (EPS), a rigid foam.
• You can cut it to size by following the gridlines moulded into it. The page says one pan fits the most common shower sizes.
• A pan liner (the waterproof sheet that goes on top of the pan) is included. The drain and the extension kit are sold separately.

What that means for you: you buy one pan and cut it to fit your space. Plan to buy the drain separately. The data sheet on the same page says the foam pan must be combined with the pan liner to be waterproof. The foam alone is not the waterproof layer.

The data sheet also lists what the pan can go on. The subfloor is the layer of wood or concrete under your finished floor. Joists are the wooden beams that hold up the floor. The pan can go on:

• a concrete slab;
• a wood subfloor of plywood or OSB (a panel made of pressed wood strands) at least 5/8" thick, on joists no more than 19.2" apart.

How do I get the shower floor level with the bathroom floor?

This is the big question for any curbless shower. The user guide on the Prova page says the edge of the pan must be level with the floor around it. The guide gives two ways to get there:

1. Raise the rest of the bathroom floor up to the height of the pan. The guide notes the pan can end up as much as 1/8" higher, depending on how much mortar is used.
2. Recess the shower area. You lower the subfloor where the shower goes. The guide says to cut the plywood subfloor without cutting the joists. Then you add extra lumber beside the joists (called "sistering") to hold a new, lower panel. It warns: "Do not cut existing joists as that will compromise the structural integrity of the floor."

Schluter's curbless brochure adds a third way: a shower tray with a ramp at the entrance. The Schluter KERDI-SHOWER-R shower ramp is a 12" x 48" ramp. Its page describes it as a "lightweight, prefabricated shower ramp with integrated waterproofing for creating accessible, curbless showers." The page says it is designed to work with the Schluter shower system. It also says the ramp gives wheelchair access and meets the ADA slope ratio. The ADA is the U.S. accessibility standard.

Two cautions:

• The ramp's spec table lists "Waterproof: No" and "Water Resistant: Yes." Treat it as one part of the Schluter system, not as a waterproof layer on its own.
• Schluter's brochure says recessing a floor must keep the structure safe. It may need a qualified design professional, such as an architect or engineer.

Whichever way you choose, follow the instructions of the system you pick, from start to finish.

Which drain should I pick: centre or linear?

Centre drain. The Prova Pan-Multi sloped shower pan, 60" x 60" has its drain in the centre. Its user guide gives the exact height for the drain pipe, below the surface the pan sits on. Show that page to your plumber before the floor is closed up.

Linear drain. This is a long, narrow drain along one edge of the shower. The Prova Linear Drain Kit, Tile-In-Top, 36" is one example. Its page says:

• It is "fully integrated for use with the PROVA LINEAR modular pan and extension system." That's the pan in the Prova Linear Pan Kit, 48" x 48", not the Prova Pan-Multi sloped shower pan, 60" x 60". Neither page says the two work together.
• "Tile-in-top" means the drain cover holds a strip of your floor tile. That way, the drain blends into the floor.
• The kit includes the drain body with a waterproofing membrane already bonded to it, the tile-in-top cover, a hair catcher and a tile spacer.
• It is made of ABS plastic. For a PVC drain pipe, the page says to use ABS-to-PVC glue.

You can compare other options in Linear Drains & Grates and Shower Bases, Pans & Kits.

How do I waterproof a curbless shower?

The Prova user guide covers three areas:

• The pan. The pan liner is pressed into modified thin-set mortar spread on the pan. Thin-set is the cement-based glue used for tile.
• The walls. The guide gives two options. One is Prova Board-Plus panels over the studs. The other is Prova's sheet membrane over a surface that isn't waterproof, like cement board. Is Cement Board Waterproof, or Do I Need a Membrane in My Shower? explains the difference.
• The open edge. Where the pan meets the bathroom floor, the guide says to use a joint strip that overlaps at least 2" on each side. It adds that a very wet room may need more waterproofing and drainage.

Remember the brochure's point: in a curbless bathroom, protect the whole floor, not only the shower. Tiling the bathroom floor too? What Is an Uncoupling Membrane? explains what goes under floor tile. You can also compare products in Shower Waterproofing Membranes.

What tile and mortar go on a one-piece shower pan?

The FAQ sheet on the Prova Pan-Multi sloped shower pan, 60" x 60" page answers three common questions:

• Tile size: use tiles at least 2" x 2". Smaller tiles might get crushed under heavy weight.
• Mortar: premium polymer-modified mortar only. That's a tile mortar with added polymers to help it grip.
• Heated floor cable: yes, it can go on the pan. The FAQ says the cables don't get hot enough to cause a problem.

When the tile is done, the user guide suggests a soft joint around the edge of the pan, where it meets the floor. A soft joint is a flexible sealant in the same colour as your grout, used instead of grout.

Is a curbless shower right for my bathroom?

Answer these questions before you buy:

• Can you raise the floor, or recess it? If neither works, look at a tray-and-ramp system.
• Where is the drain pipe? The drain has to line up with it, at the height given in the guide.
• Will you need to move anything? The Prova guide suggests placing the shower where you won't have to move heating vents, plumbing or wires.
• Do you need wheelchair access? Look at a ramp system made for accessible showers.

Not sure which setup fits your floor? Contact us and we'll help you sort it out.

Frequently asked questions

How do I choose between raising the bathroom floor and recessing the shower?

Recessing keeps the bathroom floor at its current height. But you have to cut the subfloor, and the Prova guide says never to cut the joists. Raising the floor avoids cutting, but you add material to the whole room. Schluter's brochure says recessing may need an architect or engineer.

Can I use a curbless shower pan for a shower with a curb?

Some pans work both ways. The Prova Pan-Multi sloped shower pan, 60" x 60" page calls it "a one pan solution for curbed or curbless shower installations."

Do I need a linear drain for an Italian shower?

No. A centre drain works too. The Prova Pan-Multi sloped shower pan, 60" x 60" uses a centre drain. A linear drain is a design choice. It has to match the pan system it was made for.

What size of tile can I put on a curbless shower pan?

It depends on the pan. For the Prova Pan-Multi sloped shower pan, 60" x 60", its FAQ sheet says at least 2" x 2".

Can I put a heated floor in a curbless shower?

The FAQ sheet for the Prova Pan-Multi sloped shower pan, 60" x 60" says heated floor cables can go on that pan.