How to Install a Cultured Stone Mantle

Measure the width of the fireplace with a measuring tape and then determine the center by dividing this figure in half. Mark the center with a pencil.

Determine the center of the cultured stone mantel shelf and mark the center of the shelf with the pencil. These two marks fall on the same plumb line for installation, and ensure that the mantel is centered over the fireplace.

Cut one long cleat for mounting the mantel shelf, or cut several, out of 2-by-4 lumber. Use an electric saw to create a cleat length that fits inside the width of the hollow mantel shelf. This measurement varies according to the size of the mantel hollow. The cleat should nest in the hollow of the shelf when the two are joined.

Locate the center of the cleat's length and line it up with the center of the fireplace with a plumb line for vertical placement. Check across the top of the cleat with a level for horizontal placement.

Find studs with a stud finder, drill pilot holes in the cleat or cleats with a standard drill and fasten to the wall. Use material-appropriate fasteners. For a brick or stone wall, use concrete screws. For wallboard, use either wood screws for fastening cleats to studs or anchor bolt screws for fastening to wallboard where there are no studs.

Place the cultured stone mantel over the cleats temporarily to check the horizontal placement with the level. Also, check to be sure the mantel is centered over the fireplace as well.

Remove the mantel shelf, add construction adhesive to the back edge of the shelf where it lies against the wall, and put it back over the cleats. Drill pilot holes in the shelf with a hammer drill and anchor the mantel to the cleats on both sides, the top and the bottom of the mantel. Countersink the screws and hide them with a stone filler.

Use a sanded caulk as a seal around the edges of the cultured stone shelf. Apply a bead and then smooth the caulk down with a dampened finger.