Can You Install Granite Tile Over Formica?

Importance of Bond

• Without a good bond, the granite tile will not stick and will eventually pop off the surface. There are rated substrates acceptable for use with tile installations, as not all materials work well with cement-based thinset mortars. In addition, the bond between the Formica and the substrate beneath is of equal importance to the integrity of the installation. If the Formica is bubbled or loose, those sections will need to be cut out and filled in with thinset mortar before installation so that a proper support layer can be provided.

Structural Support

• Another important element of a granite tile installation is the structural integrity of the installation. Excessive movement leads to tiles cracking out, grout cracking out and tiles eventually popping free of the thinset. Since Formica is most often used as a countertop material, there is not much in the way of foot traffic vibrations. But seasonal movement (expansion in the summer when it's warm and contraction in the winter when it's cold) can still affect the materials, and if the bond with the Formica isn’t perfect, the installation will fail. Also, if the Formica itself isn't in peak condition, it will allow excessive movement that will crack the tile out over time.

Using the Right Thinset Mortar

• If you think your Formica is in sound-enough condition to be used as a substrate for granite tile, you need to be sure you use the right thinset mortar. A number of specialty mortars are sold that can be used with nontraditional substrates such as wood or laminates; but the preferred method by most professionals is to remove the Formica first and install the granite onto a concrete board.

Sanding the Surface

• Because Formica is a smooth, laminated surface, you need to rough it up substantially before applying the thinset mortar so that the granite tile will stick to the surface. A belt sander is the most common method, because you can use a rough belt and cover a lot of ground in a relatively short amount of time. Since it doesn’t have to be pretty (it isn’t a finished surface), you can quickly and easily prep the surface for your granite tile.