Volume 38, Issue 2, February 2003
Installing Screw-In Shelf Brackets
by Jeff Oster
In order to get a shelf bracket to support weight, it needs to be fastened directly to the wall. The only way to do this is to make holes through the mirror, which we all know weakens the mirror. This is especially true when pressure is applied to the hole. The objective in the following methods is to minimize pressure on the glass by transferring it to the backing wall.
A Good Method
One-quarter-inch holes are drilled in the glass. Care should be taken to make sure that the bracket ends up level on the panel when installed. This method should only be used when both brackets are being installed on the same panel of mirror.
Plastic anchors are not very strong and should only be used for light loads. A 3/16-inch hole may be drilled in the wall after the glass panel is installed. If a stronger fastener is needed, the panel has to be put in place, hole locations marked, then removed. Mollies may then be installed before the panel is replaced.
Please note that we have used vinyl tubing. It should be inserted into the hole and trimmed with a razor blade 1/8-inch above the glass surface. When the screw is tightened, it compresses the vinyl and transfers pressure from the mirror to the wall. The vinyl also acts as a protector against the metal screw touching the glass.
A Better Method
Using a bracket with a mirrored back plate allows installers to pre-drill up to 2-inch holes in the panel to pass the screw through to the wall. It allows glaziers to be less accurate in location of the holes and will cover any chipping that may occur when drilling.
Plastic anchors, mollies or toggle bolts may be installed after the mirror panel has been installed. This allows glaziers to install a truly level shelf, even if the panel has been raised on one side.
Please note that we have installed washers between the bracket and the wall. By having the washers stick up slightly above the surface of the mirror, all pressure is taken off the mirror. Heavy pieces may be put on the shelf, providing the fasteners will hold the weight.
The Best Method
The following is the easiest way to install shelf brackets on a wall: the panels are cut to approximate widths. Allow at least 1-inch between the mirror, but anything up to 2 inches goes. The panels may be adjusted for fitting to the ceiling without worrying about the bracket location.
Wood shims approximately 1-inch wide by 3/8-inches thick may be installed directly to the wall between the mirror panels. The 3/8-inch thickness is important as it takes up the thickness of the mastic and the mirror and allows installers to transfer all pressure to the wall. Glaziers can cut the strips from 3/8-inch plywood; the easiest way to install these is by using panel adhesive and nails, which will set up in 24 hours. Plastic anchors and screws may also be used if the job requires it.
The shelf brackets may be installed easily with ordinary wood screws. The 3-inch wide mirror back plates will cover all the joints. Spacers can be used to spread the shelves apart. Longer spacers are available to cut-in on the top and/or bottom. The finished installation looks like a beveled mirror pilaster with beautiful, clear acrylic shelf brackets attached.
Jeff Oster is vice president of Mirart Inc., based in Pompano Beach, Fla.
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