Most wall-mountable medicine cabinets come with pre-drilled nailing strips already installed at the top and bottom of the cabinet (Image 1). These stabilizing strips are used to anchor the cabinet securely to the wall or wall studs using nails or (as in this demonstration) screws. The pre-drilled holes are usually 16" apart to match the standard 16" spacing between most wall studs.
Since it's fairly heavy, the best method for anchoring the medicine cabinet to an existing wall is to locate the studs behind the drywall, and secure the cabinet to them with long wood-screws. Use a stud locator (Image 1), which responds to changes in density in the wall, to help you determine exactly where the studs are located. Once you've located the studs in the wall, mark them with a small reference point using a pencil.
Once you've determined how high you want to mount your cabinet, use a tape measure to measure and mark the location of the top of the cabinet (Image 1). In most cases, the top of the cabinet should be mounted about 73" above the floor.
To determine the exact location where you'll drill your first mounting hole into the wall, inspect the back of the medicine cabinet to see how far down the pre-drilled holes are located (Image 1). Measure the distance from the top edge of the medicine cabinet's back down to the pre-drilled hole, and incorporate that measurement into your calculation. In our case, the holes were located 3" down from the top edge of the cabinet, on either side. Therefore, we measured down 3" from the reference mark made on the wall in the previous step (i.e., the mark indicating the final height of the mounted cabinet's top edge), and made a second mark to indicate the location of the first mounting hole.
Once you've got your location established, drill a pilot hole using a cordless drill and the appropriate sized bit. Note that the hole should also be placed horizontally so it will be anchored into the stud.
If you're not able to anchor your mounting screws into wall studs, there are several options for wall fasteners that you may wish to use. Depending on the weight of the cabinet, you may be able to use simple drywall anchors (Image 1). These are placed in pre-drilled holes in the drywall, and they expand as screws are tightened down in them. For heavier cabinets, you may prefer to use toggle bolts, which hold tight against the back of the drywall when installed (Image 2). When pre-drilling holes for toggle bolts, make sure to use a bit large enough to allow the toggle to be inserted. A third option is an expanding bolt that functions much like a toggle bolt or anchor and expands as it's screwed in place (Image 3).
Important: Place the bolts through the pre-drilled holes in the cabinet, and install the toggles before screwing the cabinet onto the wall.
Once your pilot hole (or mounting holes, in the case of anchors or toggle bolts) are drilled, have an assistant help you lift the cabinet into position, and secure one side of the cabinet in the pilot hole using a cordless drill and screwdriver attachment (Image 1).
With one side secured, use a level to make certain that the top edge of the cabinet is perfectly level, then fasten the other side by installing another screw or wall-fastener (Image 1).
Install the two bottom screws to fully secure the cabinet to the wall.