Supporting a Marble Mantel
Holding a piece in place
We have a big piece of marble that we'd like to use as a mantel over our fireplace. The marble is 11 inches wide, 64 inches long, and 2 1/4 inches thick and is pretty heavy. How can we hold it in place on the stud-framed walls surrounding the fireplace?
— Mary and Jim, White Bear Lake, MN
Tom Silva replies: I'd support the mantel on four 1/4-inch-thick steel angle brackets. First, cut away enough of the drywall over the framing to attach each of the bracket's vertical legs. Screw them directly to the framing with 2 1/2-inch wood screws as far around as the bracket holes will take. Don't use drywall screws.
Attach the mantel to the brackets with a bead of polyurethane adhesive on each bracket's horizontal leg, and set the marble on them. Now cover the brackets' vertical legs with fiberglass-mesh tape and joint compound.
To hide the brackets' horizontal legs, put decorative brackets underneath the mantel. You can find these made from wood, plaster, carved stone, or cast foam. If you go with wood or foam, just make sure the brackets are at least a foot away from the fireplace opening. That's what the building code requires for combustible materials.