How To Install Ceramic Floor Tile Over Plywood

I've been doing some renovation work, and was wondering whether you can lay tile over plywood. I looked at the advice from some experts and here's what I found.

As a general rule, you can lay tile over plywood. However, you need to ensure the plywood subfloor is 1 and ¼ inch (3 cm) thick. It's also recommended to use a cement backer board on top of the plywood, but some tilers make a cement backer board by hand.

A standard sheet of plywood is typically ¼ inch (0.5 cm) thick, and therefore, you'll need to add another sheet of plywood on top.

On concrete you don't need a cement backer board because the concrete is very rigid. However, plywood can be a bit too soft and create too much movement for tiles. And using a cement backer board solves this problem.

In this article I will explain everything you need to know about whether you should lay tile over plywood, and exactly how to do it.

Should You Lay Tile Over Plywood

Nervous female with power drill and hammer

Tiles look really good, and there are many different styles, shapes, and colors to match anyone's interior design taste. But, is plywood a good subfloor for it. Here's what you need to know…

As a whole, you should lay tile over plywood. But, you need to first install a cement backer board, and it needs to be 1 and ¼ inches (3 cm) thick. This is considered to be the industry standard, and ensures your subfloor is rigid enough for tiles.

However, each jurisdiction has different requirements for how thick the subfloor needs to be. And it's best to look at the recommendations from the relevant building authority in your region.

For example, the building standards in Texas are different to the building standards in New York. This article would run too long if I were to list every county and state, and the information is very difficult to find. In my opinion, you're best to contact a tiling contractor and ask them.

Overall, though, plywood makes an excellent subfloor and is more springy underfoot than concrete which makes it more comfortable to walk on.

Installing tiles over plywood is very similar to installing them over any other surface. The main requirement for having long lasting and great looking tiles is to ensure there are no air bubbles in the tile mortar used to stick the tiles to the plywood subfloor. With that being said, here's exactly how to install tile over plywood.

How To Install Tile Over Plywood

Before getting into the first step I'll first outline the tools you need

Tools Needed

Pencil
Bubble level/carpenters level/spirit level
Tile cutter
Tile spacers
Tiling grout
Tiling mortar
Buckets
Mixing paddle
Notched trowels – need bigger notches for bigger tiles
Tape measure
Sponges
Cement board
Cloth
Chalk string
Scraper
Tiles themselves
Vacuum and broom

Clean the plywood surface

Your first step should be to clean the surface of the plywood. This will make it easier to install the cement board. Use a scraper to scrape off any tape, glue, or dry plaster from the surface of your plywood. Then give the whole area a sweep or a vacuum.

Install the cement board

Installing a cement board over plywood is recommended. To install the cement board you need to lay it out and then hammer it into the plywood.

To make it really stable use your chalk string to mark out where the nails should be. A general rule of thumb is to have a nail every 6 inches (15 cm) around the perimeter and every 8 inches (20 cm) in the center.

You can create a grid pattern using the chalk string on top of the cement board. Start by hammering a nail every 6 inches around the perimeter. Then use your chalk string to make a grid every 8 inches for the nails in the middle of the board.

It may look like you're using too many nails. But it will ensure your tiling surface is solid and makes your floor last a lot longer.

Lay out the tiles

Now, you'll want to lay out your tiles to see how you want them to look. Generally, you don't want to have a thin sliver of tile on the edges. You can start by laying out a row of tiles in the middle and seeing if the edges match up.

You may find if you start at one edge and lay them out in sequence you end up with a fairly large tile at the opposite wall. However, if the end tile is too thin it's better to start with a half sized tile. As it looks the best. Cut the pieces of tile to fit using your tile cutter, and then you can begin adding the tile mortar.

Add tile mortar

The tile mortar is what bonds the tile to the cement board. The most important thing is to get really good mortar coverage on the back of the tile. This is done by using a specific technique when spreading the tile mortar.

Apply a good layer of tile mortar around a ⅓ of an inch thick. Then use your notched trowel to create grooves in the tile mortar. For normal sized tiles that are about 1 ft x 1 ft (30 cm x 30 cm) use grooves that are ⅓ of an inch (7 mm) deep.

If the tiles are smaller or larger you can adjust how deep you make the grooves in the mortar. And make them deeper for larger tiles, or shallower for smaller trowels. You can just guess roughly how deep they are. And then check your tiles every now and then to ensure you're getting good coverage.

You can do that by lifting up a tile once it has been laid to see whether the mortar is covering the entire underside of the tile, and is fairly even.

It's up to your personal preference whether you want to apply the mortar row by row, or for each tile as you do them. Now, you're ready to lay your tiles.

Lay the tiles

To lay a tile, start with it hard up against one wall, and then press it down firmly with your hands. After that drag the tile across the mortar in the opposite direction. For example if you start at the edge furthest away from you pull the tile towards you.

After you position the tile where it needs to be. You want to make sure your tile is hard up against the wall. In most cases, it's easiest to start in a corner and work your way along a wall.

When you've laid two rows of tiles you can add spacers to each corner of your tiles. The spacers will ensure your tiles are straight and are the correct distance apart. Once, you've laid all the tiles and added all the spacer you need to allow the tiling mortar to dry for 24 hours.

Final step – apply grout to the joins

Now you need to fill in the joins with grout. Start by removing all the spacers and mixing up some grout.

Apply the grout over the surface of the tiles, and push it into the space between the tiles to fill them up. The easiest tool to use is a moist sponge. Just don't add too much water to the grout with the sponge as it will make it too runny.

After you've applied the grout, wipe off all the excess using a sponge. Allow the grout to dry for a short time, and you will see a thin dry layer of grout on the surface of the tiles. Next take a damp cloth and wipe the surface of the tiles to remove any remaining grout from the surface of your tiles.

There you have! That covers all the steps to install tiles over the plywood floor.

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