A flush-mounted cabinet is the easiest to install, but because it sticks out you may feel it detracts from the visual appearance of the wall. If your bathroom does not have a recessed cabinet, it may be because there are pipes or electrical cables in the wall. You may be able to buy a flush-mounted unit and recess it partially.
1. Locate the wall studs by using a stud-finding device or by tapping a nail through the wall in places that will get covered up by the cabinet. Mark the location of the studs with a pencil.
2. Mark the position of the top and bottom of the cabinet. Make sure it's reachable by all relevant family members.
3. Temporarily brace the cabinet. With the cabinet door open, use scrap lumber to position the cabinet so it is plumb. Ideally, the studs are positioned so that the cabinet can also be centered over the sink.
4. Affix cabinet to wall. Drive screws through the cabinet and into studs. Remove bracing.
A recessed cabinet is more appealing to the eye, but requires more work, than a flush-mounted cabinet. You must cut an opening, and perhaps notch a stud, before it will slide in. But it is worth the extra work if you need the space.
Don't just mark a wall and start cutting with a reciprocating or keyhole saw. You may puncture a pipe or sever an electrical cable. If you have the blueprints for your house, they may show you the location of pipes and wires. In any case, cut carefully and slowly, feeling for differences in your saw's behavior. To be extra-safe, cut a small opening first and check for obstructions with a flashlight and a stick before making your final hole. If you find pipes or wiring, it's easier to install a flush-mounted unit rather than redoing plumbing or electrical connections.
1. Cut the hole for a recessed unit. Draw an outline of your cabinet on the wall, centered above the sink at a good height for as many members of your family as possible. Plumb the markings for level placement. Score the outline first with a knife and level, then cut it out with a keyhole or reciprocating saw. Remove the drywall or plaster and lath. If there is a stud in the way, notch it to accommodate your cabinet.
2. Frame the opening. You may or may not have vertical studs to attach the cabinet to. You don't have to frame all around the opening for the medicine cabinet, but you should firmly attach pieces of 2x at the top and bottom to secure it. Cut them to fit snugly and toenail or screw them to the studs. Reanchor the drywall or plaster to the edge of the studs with screws.
4. Set the cabinet. Once the electrical cable is attached to the cabinet, slide the cabinet into place. Check that it is plumb and centered on the sink and sets flush to the wall. Install one of the upper screws and check for plumb again. Then attach it to the framing pieces by driving in the rest of the screws.
5. Trim a partially recessed cabinet. If you were not able to slide the cabinet all the way flush to the wall because plumbing or wiring was in the way, insert the cabinet so it sticks out of the wall the same distance at all points. Wrap it with molding to cover the gap between the cabinet and the wall.
Most cabinets that come with lighting kits have the lights positioned above the mirror, even though sidelights tend to provide better illumination. If the existing light in your bathroom is adequate (if you have multiple recessed fixtures, for example), you likely can get by with a simple cabinet with no lights. If you don't have a nearby outlet, look for a unit with a ground-fault circuit interrupter (GFCI) receptacle.
If local electrical codes allow, you can install a small toggle switch on the cabinet itself. This saves you the trouble of hacking into walls to fish cable and install a standard switch. Do this only if there is room on the face or side of the cabinet for the switch and if there is a cavity available so the cable will not be exposed. Be sure to ground the light -- you'll have to attach the ground wire some place other than near the switch.
Note: Shut off power before you begin the installation.
1. Run cable to the opening.
2. For a light only: Run the power directly to the switch and then to the cabinet.
3. To wire a receptacle and a light: Run power to a junction box, then branch it to the receptacle and switch (see Illustration 1). If you need both a receptacle and a light, wire as shown for a receptacle that is always hot. Provide grounding, either with a ground wire or by means of metal sheathing. Strip the cable sheathing and about 3/4 inch of insulation from each wire. For each connection, twist the wires together with lineman's pliers, screw on a wire connector, and wrap with electrical tape. Connect the ground wire to the screw provided (black to black and white to white). Close the cover.
4. Restore power, and test.