How to Apply Faux Stone to a Fireplace

Mark the outline of the area where you wish to install the faux stone with painter's tape.

Staple metal lath to the wall surrounding the fireplace insert with a staple gun. Cut the metal lath to fit inside the painter's tape outline.

Pour mortar mix into a 5-gallon bucket. Add water according to the mortar instructions, and mix with a power drill that has a paddle attachment. Mix until the mortar resembles thick peanut butter.

Apply a thin coat of mortar to the metal lath surface with a mortar trowel to create the scratch coat. The scratch coat layer needs to be as thin as possible, but not so thin that you see the metal lath. Run the notched side of the mortar trowel over the entire surface of the scratch coat. Allow the scratch coat to dry for 12 to 24 hours.

Spread a thick layer of mixed mortar onto the back of the faux stone and press firmly onto the fireplace scratch coat. Start at the top of the fireplace surround, working on the corner pieces first. Wiggle each stone as you push it onto the scratch coat to ensure a strong bond. Repeat this procedure until all desired areas of the fireplace are covered with faux stone. Faux stone is easily trimmed and shaped to fit with a hatchet. Allow the faux stone fireplace to dry for 24 hours.

Mix more of the same mortar in a bucket. Fill a grout bag with the mortar, and squeeze the mixture into the faux stone joints. Allow the mortar joints to harden for one hour.

Push the mortar farther into the joints with a metal striking tool. Rake out the faux stone joints with the metal striking tool to your desired depth. This step relies solely on individual taste.

Smooth the faux stone joints with a whisk broom if desired. Use the whisk broom to clean away any excess mortar on the face of the faux stone pieces.