What to put down before tiling a bathroom floor?

Author: Francesca Wolff  |  Last update: Monday, August 4, 2025

Inspect your subfloor and correct any dips, cracks or uneven places that will cause your tile to buckle or not install properly. If you have a plywood or OSB subfloor, install a water-resistant cement backer board as your underlayment. Concrete subfloors typically don't require backer board.

What do you put on a bathroom floor before tiling?

Tile is best laid over a cement based underlayment. Concrete board or ``Hardy Backer'' is a good choice. This underlayment should be screwed down and screw indents filled with leveler or embossing compound.

What is the 3/4/5 rule for tiling?

To get a perfectly square corner, you want to aim for a measurement ratio of 3:4:5. In other words, you want a three-foot length on your straight line, a four-foot length on your perpendicular line, and a five-foot length across. If all three measurements are correct, you'll have a perfectly square corner.

What goes under tile flooring in bathroom?

What Constitutes an Underlayment for Tile?
  • Backer board.
  • Mortar beds.
  • Patching compounds.
  • Self-leveling underlayments (SLU)
  • Liquid and sheet membranes.
  • Uncoupling membranes.

What should I lay on my floor before tiling?

You can't, however, lay tiles directly over wooden floorboards, as the flexibility of floorboards makes them susceptible to movement, which could cause tiles and grout to crack and break. There is no need to concrete over the boards or rip them up before tiling, however, you will need to use plywood or backer boards.

How to Tile A Bathroom Floor

What do you put on plywood before tiling a bathroom?

You can install tile on plywood, but you must take a few precautions to prevent the plywood from cracking the tile. The best direct underlayment for tile on plywood is cement board or an uncoupling membrane. Follow these steps to install and use plywood as a substrate for ceramic, glass, stone, or porcelain tile.

What is the best primer for ceramic tile?

Acrylic Primer, known for its excellent bonding properties, is unmatched in its effectiveness for tiling. It improves the adhesion of tile adhesive to various surfaces, ensuring a durable and lasting tile installation.

What is the best underlayment for bathroom tile floors?

Backer board is the most favored tile underlayment option when installing ceramic or porcelain tile. It comes in rigid panels that contain a blend of cement, fiberglass, and sometimes crushed glass particles. Bedding refers to installing a backer board on top of a layer of the thin set that acts as an adhesive.

Is it better to tile over plywood or cement board?

Plywood may be the more budget-friendly option, but it is less moisture-resistant and stable than cement board. Cement board is better for areas with movement, water exposure, and subfloor imperfections, like kitchens, bathrooms, and laundry rooms. But plywood is an acceptable choice if your subfloor is dry and stable.

What are the golden rules of tiling?

The golden rule when installing tiles is install on a concrete floor where possible and always ensure it's level by applying a levelling compound beforehand – watch this video to find out exactly how.

What is the easiest tile to install in a bathroom floor?

WPC Vinyl is a combination of wood, plastic and vinyl tile, and is considered the easiest to install. This is because it's waterproof and is much more flexible and easy to work with compared to porcelain or ceramic tiles, which are brittle.

Do you have to waterproof a bathroom floor before tiling?

To ensure maximum protection, it is recommended to waterproof the entire bathroom area, including the shower, floors, and walls.

Do I need backer board for floor tile?

It's available in sheets of many sizes. Most projects need 3-foot by 5-foot sheets. Whenever you're laying tile on a wood subfloor, you need to first install cement backer board. Backer board prevents leaks and water damage that could harm your flooring and the structure of your home.

What is the best substrate for bathroom floors?

The most commonly recommended substrates for interior tile installations are cement board, exterior-grade plywood (floors only), masonry (walls), drywall and concrete.

What should you put down before tiling a bathroom floor?

Install a cement-based backer board following the manufacturer's instructions. This provides a solid surface under the tile that prevents flexing that could lead to cracking. Backer board panels typically measure 3-feet by 5-feet and can be trimmed as needed.

What goes between subfloor and tile in bathroom?

Tile Underlayment Backer Boards

Tile backer board is the most common underlayment for tile. Backer board is installed over both walls and floors and can be used in both wet and dry areas. There are several types and brands of backer board.

Does mortar go under tile?

According to the ANSI and the TCNA Handbook, tile requires a minimum of 80% mortar coverage in interior applications, and 95% for exteriors and wet environments. Natural stone tile requires 95% coverage in all areas.

What is the best base for a bathroom floor?

The best flooring options for bathrooms are floors that can withstand moisture and humidity, aren't slippery when wet, are easy to clean, and comfortable underfoot. In terms of withstanding moisture and humidity, luxury vinyl tiles (LVT), vinyl roll, and porcelain or ceramic tile are the best bathroom flooring options.

What is a substitute for cement board?

Mat-faced gypsum cover boards are increasingly used as a cement board alternative because they are lighter and easier to install. There are also performance enhancing benefits that mat-faced gypsum cover boards have over traditional cement alternatives.

How do you waterproof a bathroom floor under tile?

How to Increase Your Tile Floor's Water Resistance
  1. Step 1: Prepare the Area. Your first project is to thoroughly clean the floor to prepare it for waterproofing. ...
  2. Step 2: Prime the Tile. ...
  3. Step 3: Seal Gaps with Silicone. ...
  4. Step 4: Create a Masking Tape Guide. ...
  5. Step 5: Apply Waterproofing Sealer. ...
  6. Step 6: Apply a Second Coat.

Do I need to prime before tiling?

Before tiling, certain wall and floor backgrounds must be primed for a number of reasons including; to reduce porosity (absorbency) of backgrounds or bases (preventing the formation of air bubbles), to minimise risk of chemical reaction with cement-based adhesives and to add surface strength to friable (weak) surfaces.

Will kilz primer stick to ceramic tile?

Use on interior surfaces including drywall, woodwork, plaster, masonry, brick, painted metal, ceramic tile, glass and most other glossy surfaces. Topcoat with water-based or oil-based paint.

Can you put tile over tile?

Done properly a new tiled installation can be placed permanently over an existing tiled installation. If the existing tiled surface is dimensionally stable, has the required expansion joints, and is satisfactorily on-plane, this method can be used.

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