How to Install a Cultured Stone Archway

Sand the entire archway surface with rough grit sandpaper. Wipe off any sawdust. Use the stud finder to identify the locations of all wood studs and frame boards in the archway area where you intend to apply stone. Mark all wood boards with a clearly visible marker on each side so the locations of the wood supports are clear.

Spread lath vertically over the entire wall to be covered, wrapping the lath around the archway to give coverage that's as seamless as possible. Secure the lath in place tightly by screwing 3-inch wood screws with large plastic disc washers into the lath and into each stud or frame board, spacing the screws every 12 inches. Space the screws every 6 inches along the edges of the stones, where the stone archway will meet the regular wall.

Apply mortar to the lath with a trowel, coating the lath to a depth of at least 1/4 inch. Spread the mortar over every surface, filling in all the cracks in the lath. Let the mortar dry for three hours.

Scratch up the surface of the mortar with a spiked tool, making shallow scratches horizontally and vertically. Scratch every surface to make the mortar more receptive to stone adhesion. Let the mortar dry for 48 hours, protecting it from water.

Apply 1/4 inch of mortar to the back of the cultured stone veneers and press them against the archway for 30 seconds. Use the bigger stones first, starting at the top of the arch and working downward. Fit in smaller stones later among the large stones. Cut stones as needed to fit them in place, particularly at the bottom of the archway, where stones can be cut in half and set against the floor but only mortared to the wall.

Remove excess mortar and allow the mortar to dry for four hours. Apply grout in between the stones to meet your design specifications. Allow 48 hours for the mortar and grout to dry.