How To Install Stacked Stone Veneer on a Fireplace

Upgrading your fireplace with a stacked stone veneer can transform the look of your living space and add texture, depth, and a touch of rustic elegance to any room. In this article, we’ll guide you through installing stacked stone veneer on a fireplace, from the preparation to the finishing touches. Ask This Old House mason, Mark McCullough, demonstrates the installation process and offers expert tips and techniques.

Preparing the Fireplace Surface for Stone Veneer

Before adding the stone veneer, prepare the fireplace surface for proper adhesion:

1. Clean the existing fireplace surface with a soft-bristled brush, removing dirt, dust, and debris.
2. If the surface has paint, install a wire lath to provide a better bonding surface for the mortar.
3. Measure the fireplace surround and cut the wire lath to size.
4. Attach the wire lath to the fireplace surround using masonry anchors.

Technique Detail: Before installing the metal lath, staple horizontal lengths of builder’s felt to the front and sides of the fireplace where the stones will go, overlapping the lengths by 2 inches or more. Each length of felt should be a continuous single piece so that water in the mortar can’t seep behind the felt and cause damage. When securing the metal lath over the felt, note that one side has cuplike protrusions that keep mortar in place — this side should face forward with the “cups” facing up. It will feel rough to the touch when you run your hand down the wall but smooth in the opposite direction. Nail horizontal lengths of lath directly into the wall’s framing, overlapping each piece 2 inches or more and spacing the nails 6 inches apart.

Installing the Hearth

A well-installed hearth sets the stage for the rest of your project. Follow these steps to properly install a fireplace hearth:

1. Remove the existing hearth material using a masonry hammer and chisel.
2. Clean the exposed surface thoroughly. Any leftover debris can weaken the new installation.
3. Mix Type S mortar according to the manufacturer’s instructions.
4. Using a margin trowel, apply a layer of mortar to the hearth area and spread it evenly for a balanced surface.
5. Place the new hearthstone onto the mortar bed.
6. Wiggle the stone slightly to confirm good contact with the mortar and settle the stone firmly.
7. Use a level to confirm the hearth is even. Correct any unevenness immediately.

In the video above, Mark emphasizes the importance of creating a tight joint between the hearth and the firebox to prevent embers from falling through. Maintaining a tight seal is important for both safety and visual appeal.

Applying the Stone Veneer

With the hearth in place, you can install the stone veneer on the fireplace surround.

Preparing the Mortar

Properly prepared mortar provides strong adhesion and longevity of the veneer. Mix Type S mortar according to the manufacturer’s instructions, and add an adhesive bonding agent to improve adhesion.

Aim for a consistency similar to warm, creamy peanut butter. When applying mortar to the back of each stone, use the tip of your trowel to create a horizontal furrow on the buttered side — this groove helps lock the stone in place and creates a stronger bond with the wall surface.

Installing the Stone Veneer

Follow these steps for a safe and efficient stone veneer installation:

1. Wet the back of each stone piece with a sponge before applying the mortar. This prevents the stone from absorbing too much moisture from the mortar.
2. Using a margin trowel, apply a layer of mortar to the back of each stone. Make sure the layer is even and covers the entire back surface.
3. Press the stone firmly against the prepared surface, starting from the bottom and working your way up.
4. Use a mallet to gently tap the stone into place, ensuring good contact with the mortar.
5. Stagger the joints between stones for a more natural look. Avoid repetitive patterns for authenticity.
6. Using a wet saw, cut stones as needed to fit around the firebox and edges.

Mark demonstrates that avoiding aligning joints vertically is extremely important, as this can create an unnatural appearance. The goal is to achieve a seamless and natural-looking stone facade.

When dampening each stone, the moisture serves an important purpose beyond preventing the stone from absorbing mortar moisture — it also helps the mortar cure more slowly for a stronger bond. And once stones are in place, don’t try to wipe wet mortar off the face of the stone. You’ll end up pushing it deep into the stone’s surface pores, where it will cure and create blotches and stains that are impossible to remove. Instead, let the mortar dry and brush it off with a whisk broom.

Incorporating Corner Stones

Corner stones can create a professional, finished look. Consider the following tips for incorporating them effectively:

• Check their alignment to maintain a clean line through the corners.
• Choose corner stones that match the overall veneer to create a cohesive appearance.
• Make sure the corners are tightly butted to avoid visible gaps.

Staggering Corners: On a This Old House project, the installer explained that corners are made up of eight-inch and 16-inch pieces that alternate between courses. In the first course, an eight-inch piece goes on one side and a 16-inch piece completes the corner; in the next course, the pattern reverses — a 16-inch piece on one side and an eight-inch piece on the front. This ensures that all joints are staggered for a natural, interlocking appearance.

Making Adjustments On-The-Fly

Adjustments may be necessary to create a perfect fit when installing stone veneer. Keep extra mortar on hand to fill any gaps during placement, and use a margin trowel to smooth and adjust the stone before the mortar fully sets, which helps promote a seamless and polished finish.

Finishing Touches to Your Fireplace

To complete your fireplace makeover, pay attention to these final details:

• Allow the mortar to set for the manufacturer’s recommended time. Rushing this step can compromise the quality.
• Clean any excess mortar from the stone surface using a damp sponge.
• If desired, apply a sealer to protect the stone—this makes cleaning easier and enhances the longevity and beauty of the veneer.
• Install any additional elements, such as a mantel or decorative trim, to add character to your newly upgraded fireplace.

Maintenance and Care of Your Fireplace

Regular maintenance keeps your new stone veneer fireplace looking its best for years to come. Dust it regularly with a soft brush or vacuum attachment to prevent dirt buildup that can dull the stone’s appearance, and clean any spills immediately to avoid staining and keep the stone looking fresh. 

Avoid using harsh chemicals or abrasive cleaners, as they can damage the veneer and mortar. Additionally, inspect the mortar joints annually and repair any cracks or gaps to maintain the integrity and appearance of your fireplace.

Resources

Mark installed a stacked stone veneer by Eldorado Stone in the color “Chapel Hill,” with Type S mortar and an adhesive bonding agent, all of which were provided by Sansoucy Stone.

For the hearth material, Mark installed a slab of bluestone, which he got from Cavicchio Greenhouses.

You can find the other tools and materials required for this project, including the masonry drill, wire mesh, and masonry hammer, at home centers.

Materials

• Sponge
• Stacked stone veneer
• Stone for hearth
• Type S mortar
• Wire lath

Tools