Take these steps to add interest to your room with a coffered ceiling.
The coffered ceiling is adaptable to a variety of treatments by changing the number of steps and by adding moldings. You'll build each step from 2x lumber, which measures 1-1/2 inches thick, plus a layer of 1/2-inch drywall. As a result, each step adds 2 inches of thickness.
A room with a standard 8-foot ceiling can easily tolerate a 2-inch loss of headroom in the name of style. A second layer in that room isn't out of the question. But if you want to add a third step, your original ceiling height should be at least 8-1/2 feet to avoid a claustrophobic feeling.
The two-step ceiling has a 2x4 strip above the second strip. This additional lumber width provides a nailing surface if you want to add moldings. Cove, crown, or bed moldings are three possibilities. The addition of moldings has two positive benefits: The millwork adds style and interest, and you don't need to be as precise with your drywall work when the inside corner is covered.
Measure the desired distance from the walls, and snap chalk lines to define the perimeter of the 2x2 framework. To make a step 16 inches wide, for example, snap the chalk lines 15-1/2 inches from the walls to account for the thickness of the 1/2-inch drywall on the edge of the frame.
Using your stud finder, mark the position of the ceiling joists. Make your lines right on the ceiling between the chalk lines and the walls, because the new drywall will cover that area. Attach the 2x2 strips to the ceiling with construction adhesive and screws driven into the joists. For the strips that run parallel to the joists, add blocking between the joists.
Screw or nail a 2x2 strip around the perimeter of the room where the walls and ceiling meet. Again, use construction adhesive and drive fasteners into the studs. Don't use a level to establish a perfectly flat plane for these strips; that will merely emphasize any out-of-level condition your ceiling currently has.
Nail metal corner bead along the edges of the drywall, mitering the corners with tin snips for a neat fit. For best results, drive 1-5/8-inch ringshank nails through the metal instead of through the holes punched in the metal. Add drywall tape to the inner corners and apply joint compound to the inside and outside corners.