A coffered ceiling features a series of regularly spaced inserts, often in the shape of a square or rectangle. The inserts are typically divided by beams, elaborate molding or drywall forms. The inner surfaces of coffered ceilings can be decorated or plain.

Building Coffered Ceilings
Adding coffered beams to a ceiling involves quite a bit of finish work. Make sure your tool set includes an accurate miter, level and measuring square. If you don’t own a table saw, this would be the perfect excuse for getting one. Here are some other coffered ceiling tips:

• Box beams — Hollow box beams are the way to go if you’re creating a substantial coffered ceiling. They weight less than solid beams, are easier to work with and can be measured and constructed on the ground.
• Measure carefully — Determine the size of the room and carefully calculate the size and pattern of your recessed areas. Working with graph paper will simplify this task. Be sure to develop a cross section of your beams so you can work out how all the pieces will fit together.
• A simple mounting system — After you’ve created your U-shaped box beams, you’ll need a way to mount them to the ceiling. Consider using 1” thick stock attached to the ceiling and cut to the interior width of your box beams. The box beams can slide over the mounting board and be attached on each side with wood screws.
• Nail and glue — Since your project will exist overhead for many years, you’ll want to make sure things stay secure. Gluing pieces with construction adhesive and then nailing or screwing the piece will give you extra piece of mind.
• Off the joist — At some point, you’ll have to attach your coffer beams to areas of the ceiling that aren’t backed by ceiling joists. Take extra care in these situations: angle your nails in different directions or think about using toggle bolts t securely fasten your mounting system.
• Make use of molding — Chances are, your ceiling and walls won’t be perfectly flat. By incorporating molding into your beam design, you can cover areas that don’t match perfectly. The edges of box beams and where the beams meet the ceiling are perfect candidates for molding.
• A cure for low ceilings — Typically, coffered ceilings are limited to rooms with raised ceilings heights. It is possible, however, to create a shallow coffered effect with 2-inch stock attached directly to the ceiling. Cover the stock with veneer or drywall and edge it with molding to create the look of a coffered ceiling without sacrificing height.