How To Install Granite Tile Countertops

How To Install Granite Tile Countertops

If you are thinking about granite tile countertops for your home, here are a few installation tips and several considerations to make before you start:

The first decision to make is how the countertop edge will be finished. You can use a custom made bullnose edge, a polished square edge, wood trim, a complementary ceramic rail or cap, or a manufactured metal profile made for tile installations.

Countertop Edges
Bullnose: Granite tile is not manufactured with a bullnose profile. A bullnose edge is custom made for the job either by a company specializing in profiling and polishing stone or by a tile installer with the proper tools. To make a bullnose edge, the tile is first profiled (rounded over) and then polished to match the finished side of the tile. A diamond profile wheel on a tub saw is used to round over the edge and then several grits of polishing pads are used to gradually polish the rough surface to a smooth and gleaming finish. These tools are very specialized and expensive. For about $5.00 to $10.00 per edge, many companies specialize in this work and, considering the cost of tools and expertise necessary, it is very cost effective. Once the tiles are fabricated to a bullnose edge, the tiles are installed hanging over the base countertop edge a little more than the thickness of a tile and then a face piece is cut to about 2 inches and installed on the front of the countertop. The result is a substantially thick looking countertop with a polished edge rounding over to a polished face.

Square Polish: Another option is to simply install the tiles with slightly beveled manufactured edges over the edge of the base top and then apply the same cut face piece to the front of the countertop. Since the basic granite tile only comes with the top side polished, this will result in a ½ inch rough exposed edge, which will need to be polished to match. This polishing is commonly done with the tiles in-place, but can also be sent out for polishing first. The result is similar to the bullnose option, but with a square edge.

Wood Trim: You can also use any number of wood moldings to finish the countertop edge. This is a good looking, cost effective and in many ways, an easier option to achieve a nice finished look. Wood moldings are manufactured in a variety of profiles from simple to elaborate. They can be stained or painted to match or complement the cabinets or décor. Wood trim is glued and nailed to the front face of the base countertop and, depending on the molding profile, can cap over the base countertop finishing a small portion of the top, as well as, and front face.

Ceramic Rail or Cap: Since several ceramic tile manufacturers make a variety of specialty pieces for countertop, you could consider a complementary or contrasting ceramic sink rail or V-cap. These pieces are made with a 90-degree profile and are installed on the countertop edge. The granite tiles can then be installed inside of the ceramic pieces on the flat surface of the countertop. This idea opens numerous options and could be very bold and bright or rustic. You can let your design imagination go wild in this category. How about a bright glazed cobalt blue sink rail with Absolute Black granite or a stone looking V-cap edge framing the tan and gray tones of Caledonia granite?

Metal Edges: Many extruded metal products have been developed to finish tile edges. A primary manufacturer is Schluter Systems. Schluter makes a variety of innovative products for countertops, transitions, and stair caps.

Countertop Layout
Next, we need to consider how granite tiles will layout on the countertop.

Finished kitchen countertops extend over standard 24-inch base cabinets and are about 25¼ inches deep. All granite tiles are exactly 12 inches by 12 inches and are typically set butted together with a very fine grout seam.

In a common square set, two 12-inch tiles installed from the very front require a small remaining cut piece at the backsplash. Bath vanity tops are typically not as deep and fill easily with two 12-inch tiles.

A very good kitchen countertop option is to layout the tiles on a diagonal or diamond pattern. The measurement for one and one-half 12-inch tiles on the bias is just over 25 inches. This setting option alleviates small cuts at the back.

Using the right wood molding or a ceramic rail or cap piece on the front edge, will cheat the granite tiles enough toward the back so you wont have a small remainder cut.

You can also center a square set pattern in the countertop with a 7 or 8-inch bullnose on the front, then a full tile, leaving a large remainder cut at the back.

One other option is to insert a decorative stripe at some point in the setting pattern to add a design touch with the small remainder cut. An example would be an Absolute Black stripe through the center of an English Tan/Brown countertop.

Grout seams: As we mentioned, granite tiles are usually set butted together. Each tile has a 1/32nd inch polished bevel on each edge. When the tiles are butted together, the two bevels combine to a 1/16th inch grout seam. This seam is then grouted with unsanded grout.

Underlayment: The best setting surface for granite tile is a 1/4 inch cement board underlayment. The cement board is attached with adhesive and screws to fabricated wood base countertops or, in some cases, can be applied over existing tops (flat laminate, for example).

I like the Hardi-Backer brand because it installs flatter. It is important to make as flat a setting surface as possible. When installing screws, I use a 5/16th or 3/8th inch masonry drill bit to make a shallow dimple in the cement board in a 6 to 8-inch pattern. This helps each screw countersink to a very flat profile.

The seams in the cement board need to be taped with a fiberglass mesh type tape and filled with setting mortar. Screed the thinset over the taped seams with the flat side of a trowel and remove excess by wiping with a large grouting sponge. If you need to, you can screed over the entire surface with a thin coat of setting mortar and smooth it with a sponge.


Bedding the tiles: When bedding the tiles, full and even attachment is important.

First, apply modified thinset made for granite tiles. The thinset should be fairly thick (like peanut butter) so that it stands up and does not slump.

Comb the thinset thoroughly with a notched trowel (1/4 x 3/8 inch is probably best) to achieve a very even mortar bed. Hold the trowel at about a 30-45 degree angle. Always use the trowel at the same angle throughout the job so the thinset bed is always the same consistent depth.

Only apply thinset to an area that can be set in 15 or 20 minutes. Once you have an even mortar bed, apply a very thin and even coat of thinset to the back of a tile with the flat side of the trowel or with a margin trowel. Dont be sloppy. Keep the tile edges clean so they will butt tightly to the next tile. When this tile is laid, the thin layer on the tile back will connect to the mortar bed with full attachment. The result is a fully supported tile.

As you progress, try to apply the same pressure to each tile. Keep you hands centered in each tile so the tile is bedded evenly. Some setters use rubber mallets to bed tiles. Be careful, granite tile has natural fissures or cracks that can break. Pay attention to alignment of each seam and corner as tiles are placed.

To check that each seam is flat, try this trick. Lay a quarter flat on the surface and run the quarter across the seams with your finger. The quarter will snag or bump at irregular seams. This will tell you where to make fine adjustments to smooth out your job.