How to Lay Ceramic Tile over Plywood

RON HAZELTON:
When it comes to setting tile over plywood floors, there's no one who knows how better than master tilesetter, Armen Tavy. In fact, he's invented a patented method and material that virtually guarantees professional-quality results.

However, as Armen points out, it's what's under the tile that makes all the difference between a tile job, destined for failure and one that's guaranteed to hold up for the life of your home. That's especially true when the tile is being laid over a plywood subfloor.

Before laying tile over any plywood subfloor, it's important to make sure that the floor itself is free from excessive deflection or bending, which can pop grout joints and loosen or crack tiles.

A glass of water can detect deflection that's otherwise hard to see with your eye. A single sheet of 3/4" inch plywood is normally not adequate as a substrate for tile. The tile industry recommends a subfloor that's at least an inch-and-a-1/4 thick.

In this case, we're going to add a second sheet of 3/4" inch exterior grade plywood. The plywood seams where the sheets meet, should be offset from each other. This provides added strength and minimizes flexing at the joints.

Another way to reduce deflection is with proper nailing. Use a chalk line to mark out a grid. Underlayment should be nailed or screwed every 8 inches in the field and every 6 inches around the perimeter. The nails themselves should be long enough to pass through both layers of underlayment.

Be sure to drive all nailheads flush with, or below the surface with an extra hammer blow and leave a 1/16th"-inch gap between sheets to allow for expansion. Now this may look like overkill but a properly installed subfloor is an important key to a trouble-free tiling job.

Laying out a tile job can mean literally that. Actually laying out the tile across the room in both directions, using spacers for the grout joints. What you want to avoid are narrow slivers of tile around the edge of the room or tiles of differing widths on one side of the room, versus the other.

Slide tiles back and forth until you end up with edge tiles that are an attractive size and equal in width. The tiles that go around the perimeter of the room can be cut to width using a manual scoring-type tile cutter. A carbide wheel scores the surface, then a bar exerts pressure on both sides of the cut, cleanly snapping the tile along the line.

With the layout complete, it's now time to begin preparing the surface for tiling, using Armen Tavy's Thin-Skin system. First he applies a coat of adhesive to the subfloor, using a straight trowel. Then, he lays fiberglass-reinforced paper mats. He calls them Thin-Skin, on top of the adhesive.

Finally, he presses the paper into contact, using a wide putty or joint knife.
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Next, he mixes, then applies a Thin-Skin coat of mortar that conditions the paper. Once again, he uses a straight-edge trowel to spread the material. The mortar, in effect, acts as a sort of primer on the paper, creating a cement surface to which the tile will bond perfectly.

Using a notch trowel, Armen now applies a coat of thin-set tile mortar. Notice how he holds the trowel at a 45- to 60-degree angle, allowing the notches on the trowel edge to create uniform rows or ridges. This insures that the mortar is laid down evenly and at the proper thickness, so that the entire back of the tile will be in contact with the material.

Now it's time to set some tile.
ARMEN TAVY:
Watch the technique. I set the tile, drop it down. I'm going to push it forward about 1/4 of an inch to 3/8ths of an inch. What does this do? It takes the high ridges and drops 'em down into the low ridges or no ridges, pull it back.

What I've done is I've transferred mortar to the back of the tile, more than likely 100 percent.
RON HAZELTON:
This technique of sliding the tile back and forth not only distributes mortar evenly on the tile back, it also produces clean joints without ridges, allowing grout to be uniform in thickness and consistent in color, preventing the mortar from showing through.

As the tiles are laid, spacers are inserted to insure that the joints and grout lines are straight, even and uniform in width. This invention of Armen's called a tile puck, insures that tiles are level with each other. A tell-tale click as the puck passes over a joint means that one tile is higher than the next, a condition fixed with a couple of taps from a rubber or plastic mallet.

Once the tile is laid into the thin-set mortar, it should be left to dry for at least 24 hours before grouting. Then the spacers can be taken out. In this case, Armen uses his feet in what may look like the dance of the tile fairies.

Grout should first be mixed dry to blend all the ingredients and insure uniform color. Then water is added and the mixture is stirred until it's smooth and creamy.
ARMEN TAVY:
Now, we're going to let that slake.
RON HAZELTON:
A sponge rubber float is used to apply grout. Armen first forces the material all the way to the bottom of the joint, completely filling it. Then he tilts the float up on edge and moving diagonally from corner to corner, removes any excess material from the face.

If the float is not kept on the diagonal, it can scoop out grout previously put into the joint.
ARMEN TAVY:
Now the more we remove off the tile with the float, the less we have to wash when it's time to wash it.
RON HAZELTON:
The grout is then left to dry about 45 minutes to an hour until the material is firm in the joints and a dry haze is visible on the face of the tile. At this point, it's time to clean off the remaining grout, using a grout sponge, dipped in water.
ARMEN TAVY:
We're going to take about 80 percent of it out and leave some behind. We're going to take the sponge and just coat it over the tiles.

RON HAZELTON:
For the final wash, Armen tips the sponge up so that just the edge is in contact with the tile, and makes four strokes.
ARMEN TAVY:
Flip the sponge over. Third stroke, fourth stroke.
RON HAZELTON:
Once the tiles are thoroughly dry, any remaining haze is removed with a soft cloth.
ARMEN TAVY:
Here's a normal cloth, simple clean cloth. We're going to take this up, bundle it up like this, we're going to get it onto the haze, we're going to rub the haze just like we're polishing our car and this is as good as it gets.
RON HAZELTON:
So let's recap — the system consists of adhesive, reinforced paper, a Thin-Set skin coat, a Thin-Set bedding coat and the tile. And the whole thing, including the tile is less than 1/2 an inch thick.