How To Install Stone Veneer on an Exterior Wall

Stone veneer can transform the look of any building. Its natural beauty and durability make it an ideal choice for adding texture to exterior walls. However, installing it on an exterior wall requires more than just sticking stones on.

If done improperly, it could lead to issues like moisture infiltration or structural damage. Knowing how to install stone veneer on exterior walls properly will make sure that your project lasts for years without these concerns.

A well-installed stone veneer can dramatically improve the visual aesthetic of your home. This gives it a timeless, elegant appeal. The installation process is detailed but manageable if you follow the right steps.

Here, we will walk through the methodical procedure to install stone veneer on your exterior wall, step by step.

Planning and Preparation

Before picking up the tools, preparation is key. Planning the project ahead of time can save you from mistakes and unnecessary work. Start by gathering all the necessary materials.

For an exterior wall, you will need stone veneer, mortar, a weather-resistant barrier, metal lath, nails or screws, and various hand tools such as a trowel, brush, and grinder. The quality of materials is just as important as the technique used.

Start by calculating the square footage of the wall to determine how much stone veneer you need. Measure the area to be covered, including any openings like windows or doors. If your project includes corners, adjust for the stone required in these areas. Subtract 1 square foot for each linear foot of corner space, as you will need special corner pieces.

Once you have your materials, prepare the surface where the stone veneer will be applied. This preparation makes sure that the mortar has a proper surface to bond to–vital for the longevity of the installation.

Surface Preparation

If your exterior wall is made of concrete, masonry, or stucco, you can apply stone veneer directly, provided the surface is clean and free from dust, paint, or other residues. If you are working with a framed exterior wall, you will need to install a weather-resistant barrier such as tar paper.

For framed walls, start by applying the weather-resistant barrier, overlapping the joints by at least 4 inches. This will help prevent water from seeping through the stone veneer and into the structure of the building.

Next you will need to attach a metal lath. This lath creates a rough surface to hold the mortar. It should be fixed to the wall using galvanized nails or screws, spaced 6 inches vertically and 16 inches horizontally. The lath should also overlap by at least 4 inches at the corners to guarantee a secure fit. Fiberglass lath is also available; they are lighter and corrosion free, should that be desired.

In some cases, you might need to attach the lath to the wall before applying the weather-resistant barrier. If your surface is particularly difficult to work with, you may need to add a scratch coat before installing the lath.

A scratch coat helps the mortar bond better to the surface, especially on smooth surfaces like concrete or stucco.

Mixing and Applying the Scratch Coat

If you are using a metal lath, applying a scratch coat is a must. This layer of mortar serves as a bonding agent for the stone veneer. It also gives the mortar a rough texture. This helps the veneer adhere better. The scratch coat should be applied evenly and left to dry for 24 hours before proceeding.

To make the scratch coat, mix one-part Type S masonry cement with 2.5 parts sand. Gradually add water while stirring to achieve a paste-like consistency. The mortar should be thick enough to stick to the surface but smooth enough to apply easily. Once the mixture is ready, apply it evenly over the metal lath, creating a layer about 1/2 to 3/4 inch thick.

After applying the scratch coat, use a notched trowel to create horizontal grooves while the mortar is still slightly wet. These grooves are necessary because they give the stone veneer mortar something to grip when applied. Allow the scratch coat to dry for a full 24 hours before moving on to the next steps.

Preparing the Stone Veneer

Once the surface is ready and the scratch coat has dried, the next step is preparing the stone veneer. Lay out the stones in the area where they will be installed. This step will help you plan how to place the stones and guarantee a consistent and visually pleasing pattern.

It is important to mix and match the stones during this process to avoid a repetitive or too uniform pattern. Try to vary the sizes and colors of the stones so the installation looks more natural. If you need to cut any of the stones to fit the space, you can use a masonry saw or a nipper to trim them.

Before applying the stone, clean it thoroughly. Dust, dirt, and loose particles can interfere with the bonding process. You can use a damp cloth or a soft brush to clean the surface of the stones.

If any of the stones are especially dusty, it may help to rinse them with water. However, make sure they are completely dry before applying them to the wall.

Installing the Stone Veneer

The process of applying stone veneer to the wall requires a steady hand and a bit of patience. Start by mixing the stone veneer mortar (SVM)–a specially formulated mortar that bonds well to both the stone and the scratch coat. Mix the mortar according to the manufacturer’s directions, typically using a pre-blended, polymer-fortified Type S mortar.

Begin the installation with the corner pieces. These will set the tone for the rest of the veneer. Lay them out first and make sure they fit well. After placing the corners, start working your way from the bottom of the wall to the top. This allows the mortar to set more evenly and prevents any stones from slipping as you work.

When applying each piece, use a trowel to butter the back of the stone with a 1/2 to 1-inch layer of mortar. Make sure to create a ridge around the edges of the stone. This ridge will create suction when pressed against the wall and help the stone stay in place.

Once the stone is in position, press it firmly into the wall. You should also slightly rotate the stone as you press it in. This helps distribute the mortar evenly.

It is important to dampen the back of the stones before applying them to the wall. This prevents the stone from absorbing moisture from the mortar too quickly, which could weaken the bond. Use a masonry sponge or a brush to dampen the back of the stone lightly, but do not saturate it.

Finishing the Installation: Grouting and Tooling the Joints

Once the stone veneer has been placed on the wall, the next key step is grouting the joints. The mortar used for the grout serves to fill the spaces between the stones. This provides structural support and a finished look. This part of the process requires precision to assure that the joints are clean, smooth, and evenly spaced.

To begin, you will need to mix a pre-blended Type S mortar. It is important to follow the manufacturer’s instructions to achieve the proper consistency. You can also opt for mortar designed specifically for stone veneer to enhance the bond and flexibility of the final result.

Once the mortar is mixed, fill a grout bag about halfway with the mixture. Twist the top of the bag securely to avoid spills, and test it by squeezing a small amount of mortar into a bucket to remove any air pockets.

Once ready, begin to fill the joints between the stones–starting at the bottom of the wall and working your way upward. This technique prevents mortar from accidentally spilling onto already grouted areas.

For the joints, aim for a 1/2-inch layer of mortar. You can adjust the thickness depending on the desired appearance of the joints. As you squeeze the mortar into the gaps, use your fingers or a joint tool to press it in and compact it for a firm hold.

Be careful not to overfill the joints; excess mortar can cause unsightly lumps or uneven surfaces.

Tooling the Joints

Once the mortar has been applied, it will begin to set and harden. While it is still slightly wet but firm enough to hold its shape, you can tool the joints to create the final appearance. Tooling refers to smoothing the grout to your desired depth and finish.

Use a joint tool designed to give the mortar a uniform depth and shape. Run the tool along the grout line. This makes sure to remove any excess mortar from the surface and helps give the veneer a more polished, professional look. If you want to create a more textured or recessed joint, you can experiment with different joint tools or simply adjust the amount of pressure applied.

After tooling, use a whisk broom to gently brush the joints–smoothing them further and cleaning away any remaining mortar. This will give the finished surface a consistent, clean look. It also helps remove any residue that could harden on the stones over time, potentially damaging their appearance.

Wrapping Up the Stone Veneer Installation Process

Installing stone veneer on an exterior wall can greatly enhance your property’s aesthetic appeal and durability. With the outlined steps on how to install stone veneer on exterior walls, you can confirm that your stone veneer installation is functional and visually striking.

Proper care during installation is key to achieving a professional finish. Maintenance after installation will keep the stone looking its best for years.

Ernest Maier is committed to helping you achieve exceptional results with the right materials and expert guidance. No matter if you are working on a small residential project or a larger commercial development, our team offers high-quality products and support to make your installation process as seamless as possible.

Visit us for natural and manufactured stone veneer options and more masonry and outdoor living resources to assure your next project is a success.

Sales-Outdoor LivingKen Cook

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240 508-5123

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MD: Baltimore

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