Depending on the lighting in your bathroom, you may want to add lights at the top or on the sides. And if you find that you have to stretch electrical cords across the bathroom, you may want to choose a cabinet model that comes equipped with a GFCI (ground fault circuit interrupter) receptacle. Installing a simple cabinet will take a few hours at most; adding electrical service and lights can take much longer. If you are not sure of your electrical knowledge and skills, consult with or hire an electrician.
A flush-mounted cabinet simply mounts to the surface of the wall; putting one in is a snap. However, it will probably be shallower than a recessed cabinet, and it will protrude into the bathroom space.
If your bathroom does not have a recessed cabinet, there most likely is a reason. Chances are, plumbing pipes lie directly behind the space, making it impossible to fully recess a medicine cabinet. You may want to settle for a flush-mounted cabinet.
But if every inch of space matters and you want a deeper cabinet, it may be worth your while to open up the wall and investigate whether you can at least partially recess the cabinet. Then you can trim it with molding to give it a finished appearance.
1. If the old cabinet has electrical lights or a receptacle, shut off the power at the service panel before proceeding. Remove light bulbs and electrical cover plates. Disconnect wires and loosen cable clamps so the cable can slide freely through the holes.
2. Empty the cabinet, and look for screws or nails holding the cabinet in place. Unscrew or pry out the fasteners and lift out the cabinet. Avoid damaging electrical cables as you work.
3. Measure the rough opening and look for a cabinet that will fit. In the case of old houses, you may need to enlarge the opening (a messy business) or close it up some. If the flange of the new cabinet does not cover the opening completely, you will need to install molding.
4. Use a stud finder or a hammer and nail to locate the studs. If possible, position the cabinet between studs; otherwise, you will have to cut a notch in a stud to make room for the cabinet.
5. Draw the rough opening of the cabinet on the wall, checking to see that it is level and square. It should be centered over the sink and at a height that will make the mirror usable by all members of your family.
6. Work carefully to avoid cutting through any pipes or electrical cables hidden inside the wall. Blueprints may show you where the pipes are. If there is a plumbing-access panel on the other side of the wall, open it and look around with a flashlight. Cut slowly, feeling for anything that might be a cable or pipe. Though a keyhole saw is slower than a saber saw, it is safer. Notch studs as needed. If electrical cable needs to be moved, shut off the power at the service panel before touching it.
7. Shut off the power at the service panel. Run power to the switch, then to the opening. If you will be installing lights only, there's no need to worry about overloading a circuit. However, appliances like hair dryers can require plenty of amperage, so if you are installing a receptacle, make sure the circuit does not service other heavy-amperage appliances or outlets.
8. Wire connections must be inside a junction box installed in the wall or inside the box that is part of the cabinet. Strip the cable sheathing and the tips of the wire ends. Connect to the wires for the light (black wire to black wire, white to white, and ground to ground). Replace the cover plate and secure the cable.
9. Slide the cabinet into place and check that it is level and plumb. Make sure the door does not open or close by itself; you may have to shim out the bottom or the top if it does. Attach the cabinet, studs, or other framing pieces by driving screws.
10. If you can't slide the cabinet in all the way because of an obstruction in the wall, slide it in as far as you can and attach to the studs with screws. Wrap the perimeter of the cabinet with molding to cover the gap between wall and cabinet. If the side of the cabinet is unattractive, wrap it with molding.