No one can claim that making a coffered ceiling is quick and easy. Faux beams make the job a lot easier, but there's an art to making each joint look good and stay tight. Here's the best way to create perfect four-way mitered joints. 1. Carefully plan, measure and lay out the grid pattern of the coffers. Snap a chalk line on the ceiling along the center line of each beam to make a checkerboard with perfect right angles. 2. For each intersection on the checkerboard, make a crossed mounting block from two pieces of 2-by lumber. Rip each piece to the exact width of the inside of the beam, and make its length about three times its width. Screw and glue the two pieces together at right angles. Then anchor each crossed block to the ceiling aligned with the chalk marks. 3. Take time and care cutting and dry-fitting each beam. At each four-way intersection, miter each beam in a V using a precision miter saw. 4. Stain the mitered edges to match the finished beam. This helps hide any imperfections in the joinery. 5. Mount the beams to the blocks. To lock everything together as a single unit, use adhesive on every mating surface: the mitered edges, the inside of the beam where it slips over the mounting block, and the edges of the beam that touch the ceiling. Apply a light bead, slightly back from exposed edges to avoid squeeze-out. Screw through the sides of each beam into the mounting blocks as usual. 6. Carefully wipe away any excess adhesive that squeezes out. 7. Step back and admire the perfect joints that will stay that way for a long, long time.