What to Do About Shoddy Floor Tiles

Get expert tips on how to repair tile flooring.
By: Dwight Barnett

Q: In December I had ceramic tile installed in my kitchen, on the stairs and in two vestibules. The area is about 180 square feet. The installer used only one bag of thin-set mortar for the job. The bag states that for my tiles, one bag covers 55 to 65 square feet.

I noticed the next day that there was no mortar showing between the tiles. Later, I noticed some tiles had popped, cracked and sagged, a lot of the grout had cracked and the edges of the tiles do not meet properly.

The installer refuses to redo the job, stating that he performed the work properly and up to standards. Unfortunately, we paid him in advance. What is your opinion on the likelihood that more of these tiles will crack and come loose? The installer states that the strength of the tile will hold them. It is a quality porcelain tile, but things I have read indicate that the tile is only as good as the base on which it is installed. He did screw down plywood over the existing subfloor, although it's obvious he didn't hit any floor joists with the screws because there is still a pronounced hump in one area of the floor. — N.C., Windsor, Ontario

A: One bag of thin-set mortar is used to cover roughly 60 square feet of floor space if the installer spreads the mortar all over the floor using a quarter-inch notched trowel and then sets the tiles into the mortar.

If the installer spreads the mortar on the back of each tile, in a process called buttering, one bag of mortar will cover a much larger area.

If you were not able to see the mortar on the floor between the tiles, then they were buttered in place.

If you will read the instructions on the bag of mortar, it will probably advise the user to butter larger porcelain tiles and to use a modified latex thin-set or a thin-set mixed with an acrylic latex additive.

I'm willing to bet your installer mixed the thin-set with water, which makes the thin-set more brittle.

A good installer will butter the tiles and compress each tile in place. If the tiles are loose and uneven, they were not compressed or installed properly and need to be removed.

Unfortunately, the installer is long gone, and so is your money, so you'll have to do this yourself.

Never, ever pay in advance of a completed job.

You are also correct to assume that the subflooring is not installed properly. When there are humps or damaged floors that need to be covered, the subflooring needs to be installed in a bed of thin-set mortar to level out the old floor and to cover any imperfections.

Screws or ring-shank nails are then used to fasten the subflooring to the original floor before the thin-set has had time to dry. The screws need to be set every 4 inches along the edges of the subflooring and then every 6 inches over the remainder of the sheet.

I guarantee you that some of the screws or nails will find a floor joist if you use long fasteners. The nail or screw used should penetrate both the subfloor and the original flooring and protrude.

I have seen tile floors fail because the installers used staples to secure the subfloor or because the subfloor was not set in a thin-set mortar bed.

Some installers prefer to use wood glues or construction adhesives to secure the subfloor instead of thin-set mortar, but this is usually found on new construction, not on remodels or overlays.

My advice would be to remove all the tiles and the subflooring and do the job right.

Dwight Barnett is a certified master inspector with the American Society of Home Inspectors.

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