Pictured is EarthSlate stone tile from Walker Zanger, in 24” by 24” floor sizes and a random wall pattern.

The beauty and performance of stone tiles is prized by many homeowners and builders, leading to its use in more projects than ever in both residential and commercial settings. This, in turn, has led to more questions about the techniques and nuances associated with the installation of stone tiles. There are several key items retailers should be able to convey while chatting with their customers, so let’s review a few areas that will help them work with their customers.

Stone Types and Applications

It is important to understand what type of stone the customer wishes to use and how he or she wishes to use it. Ask about the area or application the customer has in mind. Will the stone tiles be used in a wet area, such as a shower or tub? Will they be exposed to high traffic such as in an entryway or mud room? Are they likely to be exposed to household cleaners, food acids and oils normally found in kitchens? The answers can help you narrow the choices and determine a finish type that is suitable for the application. For instance, some stone types such as granite or quartz will wear better in high-traffic areas. They are far more durable and can stand up to scratching and wear.  Limestone and marble, on the other hand, are more porous and may not be suited to food acid or oil exposure. The finish of the stone also plays a role in its performance. A polished finish may be suitable for wall applications and floors in low-traffic areas. Honed and flamed finishes are appropriate for high-traffic areas and other applications where abrasion and slip resistance come into play.

After helping the customer select the right stone the next step is to help them with the installation materials and techniques.

Large Format Stones

We are seeing a clear trend toward flooring stones that are growing in face dimension size but shrinking in profile thickness. The challenge for the installer is to create a permanent bond and guard against cracking. With large format stones it is crucial that the stone is well supported by the adhesive mortar. (We will assume the substrate meets rigidity standards and is properly prepared.) Most stones vary in thickness so the adhesive mortar needs to accommodate for that. At the same time, it also must be able to support and set the stone under its entire area. Some mortars simply cannot do this. Use a suitable marble and granite mortar that is designed to set the stone properly and supports the weight of the stone. Most adhesive manufacturers offer products that are specially designed to be used with stone.

Preventing Cracks in Stone

Cracks in a stone floor compromise its appearance. It is a blemish that all of us in the industry want to avoid. There are several ways to prevent cracking. We can start by using an anti-fracture membrane over the substrate. Generally, they are easy to apply. Some are applied with a liquid roller, while others are available in peel-and-stick type sheet products. These materials can be used to treat existing cracks on the substrate as well as guard against cracks that can develop over time. Once the anti-fracture membrane is in place, good installation techniques should be followed when setting the stones. For thin-bed and medium-bed installations, this includes using the appropriate sized notch trowel and back troweling the stones to ensure complete setting of the product with no voids. It is a good idea to periodically pull up a freshly installed stone to verify the coverage and mortar transfer. All of these methods are all that more important if the stones being used are thin and fragile. The thinner the stone, the more effort is required to ensure a good installation.

Other Considerations

There are several other things to consider when installing stone. One issue is the stability of the stone itself. If the stone is water or moisture sensitive and prone to curling (usually green marbles and some agglomerates), use a 100 percent solids epoxy adhesive. On the other hand, use a white colored adhesive mortar for light or white colored stones. Some installers will only use a white mortar regardless of the stone color to avoid confusion on the job site.

Watch for expansion joints that may exist in the substrate and bring them through the stone finish. Movement joints should be placed at the perimeter of the installation as well as in the field. Follow the Handbook for Tile Installations (TCA) guidelines outlined in Expansion Joint Detail EJ171. Although this is a tile industry publication, the Marble Institute of America also refers to it in their installation manual. Use a suitable flexible sealant that is non-staining and will stand up to the high traffic and maintenance wear and tear that the product will endure. Note that most acrylic-type colored caulks are not suitable for these installations.

Grout for Stones

As the finishing touch, grout should complement the stone installation. Most of the problems that occur with stone installations are related to the grout, whether color consistency or durability. A compatibility test should always be performed on the stone with the grout that will be used. Some stones may require that sealer be applied to the face of the stones to make the grouting and clean up process easier. Some stones may be stained by the grout if the sealer precaution is not followed. If a Portland cement-based grout is chosen, the use of a high quality latex-fortified grout is always a good idea. There have been great strides with new products in this area.  For even better performance, new types of grouts can be used that address common problems associated with stone installations. These products include a unique cross-linking technology grout and various epoxy-based grouts.

The bottom line is this. Stone use shows no signs of slowing, and neither does the innovation behind new installation materials and techniques. Check with your stone installation manufacturer for their suggestions on new products and new installation trends and techniques. .Of course there is much more to know. If you will pardon the expression, we have just scratched the surface on stone applications.