Cut holes in the plywood to match the existing holes in the wall or ceiling. Remove the cover plates and the screws holding the switch or receptacle to the box. If you are using metal extenders, play it safe and wrap electrical tape around the sides to cover the contact screws and bare wires so that they cannot make direct contact with the box later on. Install the plywood and then slip the extender around the wires and into the box. Use the extra-long screws that should be included with the extender to secure the switch or receptacle to the extender and the box. After the finish has dried, reattach the cover plates.

Another problem will arise if you try to attach plywood to walls containing doors or windows. Depending on the type of trim that surrounds the door or window, you may either need to remove and readjust the trim or leave it in place and add some small molding (cove or quarter round) to cover the gap between the plywood and the existing trim. The solution here may be very simple or very complicated, depending on the house involved. Either way, it is wise to figure out exactly how you plan to tackle the problem before you buy any materials and begin working.

Finally, if you are covering entire walls with plywood, you will need to figure out what to do about existing baseboard trim, and perhaps crown molding as well. In most cases, it will look best if you remove the existing trim, attach the plywood, then add new trim pieces that complement the framing members used elsewhere on the wall.

Attaching the Plywood and Trim

Use 1 1/2-inch finish nails to attach the plywood to the wall and somewhat longer nails for the trim pieces. All nails must be driven through the wall and into the framing; nails that are driven through drywall alone will not hold. Wall studs and ceiling joists should be located at regular intervals, usually centered every 16 or 24 inches. You may be able to locate the framing members by rapping on the surface with your knuckles. When the sound turns from hollow to solid, you are over a stud or joist. A safer and more accurate method is to use a battery-operated stud finder, which you can purchase at any home-improvement center.

Used as directed, a stud finder works great for locating framing members behind drywall, though it is less useful with plaster. Mark the stud or joist locations on surfaces you are covering, then plan to drive your nails at those locations. Space the nails about 12 inches apart. Be very careful when driving nails, as you do not want to dent the surface with stray hammer blows. Use a nail set to drive the head of the nail below the surface. Before applying your finish, fill all of the nail holes with a wood putty that matches the color of the wood.