How to Build a Coffered Ceiling

Apply basic carpentry techniques to primed boards and molding to add a formal, elegant touch to any room

By John Casey

If you’d like to add dimension and character to a plain room, nothing beats the traditional look of a coffered ceiling, with its grid of bold beams. Constructing coffers on your own may seem daunting, but we’ll show you how even the average DIYer can create this hallmark old-house feature. The secret is our low-profile coffer design, which greatly simplifies the task of working overhead because you’re installing flat boards and molding rather than assembling box beams.

See for yourself as This Old House contributor Chris Beidel, owner of Pernt, a handmade-furniture company in Brooklyn, New York, walks you through the steps of this ceiling beautification project.

Primed lumber: WindsorONE+ 1x6 finger-jointed pine, $1.35 per linear foot; WindsorONE

Coffered Ceiling Overview

Day-to-day timeline

SATURDAY Install the beams (Steps 1–12).

SUNDAY Install molding, and paint (Step 13-16).

Step 1: Locate the Joists

Work out your design on graph paper, mapping lights and major features of the room. We centered our nine-coffer grid around an existing chandelier. Measure and mark where your “beams” will meet the walls, and use painter’s tape to simulate them, to see how the pattern fits the room. Use a stud finder to locate the ceiling joists. Mark both ends of each joist where it meets the sidewalls. Put a ⅛-inch drill bit in your drill/driver and make test holes near the walls—they’ll be covered by the beams—to verify joist locations and make sure you catch their centers.

Step 2: Make a Deadman

Use scrap lumber and your drill/driver to make a T-shaped deadman, as shown, ¾ inch shorter than the height of your ceiling. It will hold one end of the beam against the ceiling as you work.

Step 3: Cut a Beam

Measure for the first main perimeter beam. If your room is square or irregular, start with a perimeter beam that runs perpendicular to the joists, to create a firm connection to the ceiling. (If you need two boards to span the length of your room, join them with a plain scarf joint at a joist.) Cut the beam on your miter saw ¼ inch too long. Dry-fit the piece, then apply panel adhesive to the length of the beam. Butt one end into the corner and hold it there with your deadman, as shown.

Tip: The beams need to be tight to the ceiling at the joists, but any gaps that appear between joists will be covered later by the molding.

Step 4: Nail the Beam in Place

Tuck the other end into the opposite corner, creating a bow. Begin at one end and work across, firing two 16-gauge pneumatic nails into each joist with your pneumatic nailer. Voids will be covered with molding and caulk. Measure and cut the opposite perimeter beam, and repeat the installation process.

Step 5: Scribe the Perimeter Crossbeams

Measure between the main perimeter beams at each end of the room. On a miter saw, cut two 1x6s 3 inches too long. Using the deadman, hold a rough-cut board overlapping the main beams at each end, and mark where it crosses a beam at one end, as shown. To mark its back edge, lay the board face to the wall. Use a straightedge to connect the front and back marks, creating a scribe line. Scribe one end of the other beam, too.

Step 6: Cut Along the Scribe

At the miter saw, adjust the blade to match the angle of the scribe line, and make the cut. Repeat for the other beam. Now scribe and cut the opposite end of each beam, leaving them ⅛ inch too long, for a tight fit.

Step 7: Shim the Seam

Apply adhesive to a perimeter crossbeam and hold one end in place with your deadman. Fit the other end in place. If the joint is not flat, use shims to bring the surfaces of the two beams flush, as shown. Use the nailer to fire two nails at opposite angles every 12 inches along the perimeter crossbeam. Remove excess shim by scoring it with a utility knife and snapping it off.

Step 8: Snap a Chalk Line

With the perimeter installed, you can measure and mark locations for the main beams and crossbeams. Use your marks to snap a line with nonstaining chalk to mark one edge of each beam, as shown; then snap lines over each joist.

Step 9: Cut the Main Beams

Scribe and cut the main beams the same way you did for the perimeter crossbeams in Steps 6 and 7. Then apply adhesive to a beam and pressure-fit it in place, using your deadman to hold one end. Use shims to make the joints flush as needed, nailing through them and into the ceiling at every joist. Install the other main beam the same way.

Step 10: Cut the Crossbeams

Cut the board for the first crossbeam 1 to 2 inches too long for the space between two main beams. Then use the scribing technique from Step 6 to cut first one end and then the other, to create a tight fit. Dry-fit the piece in place, as shown. If sized correctly, the crossbeam should fit snugly in place.

Step 11: Mark Joint Locations on the Crossbeams

Use a rafter square to confirm that the joint at each end is at a 90-degree angle, and mark where both edges of the crossbeam meet the main beams.

Step 12: Toenail the Joints

Pop the piece out, apply adhesive to it, and set it back. Shoot a nail through each corner of the crossbeam into the ceiling. Then, with your nail gun held at about a 45-degree angle to the joint, toenail through the corner of the crossbeam and into the main beam. Toenail the other corners of the crossbeam, too. This will help hold the joints together as the wood expands and contracts with the seasons.

Step 13: Scribe the Molding

Measure the interior dimensions of all four sides of the first coffer. On your miter saw, cut inside 45-degree angles on each end of your molding, leaving each piece about ¼ inch too long. Then scribe each piece by holding it in place, as shown, and marking the overhanging material.

Step 14: Finish-Cut the Molding

Trim the excess on your miter saw, as shown. Then dry-fit the piece in the coffer. Repeat the process until all the pieces fit snugly in place.

Step 15: Glue and Nail the Molding

Apply wood glue to each piece of molding. (Panel adhesive is thicker than wood glue and could cause the molding to stand off the beams.) If you have gaps between the ceiling and the beam, split the difference when you set the molding in place to hide any variation across the coffer. Use an 18-gauge brad or pin nailer to nail the molding in place. Repeat the process on all the coffers. Apply latex caulk as needed to finish the joints and cover any gaps.

Step 16: Prep and Paint

Apply wood putty with a putty knife to the nail holes. Sand the putty smooth. Use a 2½-inch sash brush and semigloss paint to finish the molding. Then use a small paint roller to finish the beams.