The real solution involves the installation of furring strips—either wood or resilient channels. Find the lowest spot on the ceiling and shim all the furring to that point. It’s not as difficult as it sounds. The procedure shown here is a systematic method for locating the lowest spot on a ceiling, then installing the furring strips. You may need a good number of shims to complete the furring strip installation, but you can easily make them at home from scraps of plywood and hardboard. The amount of time you’ll spend on this project depends on the condition of the ceiling. For a room that measures 10x12 feet, you and your helper should allow 4-6 hours to check the ceiling and install the furring. Before you begin, clear the room, and mark the location of all the ceiling joists. Editor’s Tip: A drywall ceiling suspension system is somewhat like the familiar dropped ceiling that accepts tiles, but the members are engineered for face-application of drywall—up to doubled 5/8-inch panels. You’ll lose a few inches of ceiling height, but the metal system installs fast and produces flat framing for great results. Editor’s tip: For this project, flat shims work great to fill most of the space. Make your own by ripping 2-inch wide strips of 1/8-inch hardboard and plywood that’s 1/4- and 1/2-inch thick. Crosscut the strips into 4-inch lengths with your miter saw. By combining these three thicknesses, you’ll quickly fill the openings between the furring strips and ceiling. For fussy final adjustments or leveling, use tapered shims in pairs—install one from each side of the strip—so that you don’t twist the wood.
