How to Build a Coffered Ceiling With Box Beams
Built of plywood and MDF, these beams go up quickly, resist movement, take paint well, and even level a wavy ceiling.
Synopsis: Open areas might be nice, but they can seem cavernous without a way to differentiate the space. For architect and builder Joseph Lanza, one way to overcome that obstacle is with coffered ceilings. In this article, Lanza focuses on the construction of the box beams that he uses as the basis for the coffered ceilings he builds out of medium-density fiberboard and plywood. He also offers advice on dividing ceiling space and leveling wavy ceilings
Like many of us, my clients tend to do most of their living in open rooms that serve multiple purposes. But in the small older houses in southeastern Massachusetts where I do most of my design and remodeling work, large rooms are rare, so I end up taking down walls or building additions to create them. Removing walls and adding small bump-outs change the scale of a space, which can make it look and feel awkward. When this happens, a coffered ceiling can create a more comfortable scale and restore order by dividing a big space into separate areas. Even though most of the beams in a coffered ceiling are hollow, they should look like a convincing structural system. Once the beams are built, each recess is typically finished with molding, but I’m focusing here on creating the box-beam grid.
Make use of existing beams
Nonstructural hollow box beams can carry a lot of architectural weight, but it’s often necessary to combine them with a structural beam when walls have been removed.
In the kitchen/dining/living area shown here, we bumped out a 40-ft.-long exterior wall by 6 ft. and replaced it with a 16-in. LVL beam supported by two 3-1⁄2-in.-sq. columns. The beam bisected the ceiling into long, narrow areas disproportionate to one another. I needed to divide the ceiling into sections that made sense visually while incorporating the LVL and columns.
To mark the divisions between the three areas, I began by adding two large box beams measuring roughly 9 in. by 9 in. Because most of the LVL was buried in the ceiling, I was able to make the two bigger box beams appear to carry the structural beam. To balance the design, I ran a box beam on the right side of the fireplace, parallel to and the same size as the wrapped LVL.
This extra beam made the main-ceiling sections roughly symmetrical throughout the room, but put the fireplace off center. To anchor and balance the fireplace, I added a matching beam to the left, but stopped it at the larger beam that divides the living and dining areas. The additional beam serves an important function in the living room. But carrying that beam through the space would have divided the dining area and the kitchen in an awkward, unnecessary way.
It’s not really symmetrical, but the layout works because at first glance it makes visual sense. The beams are big enough to make the ceiling look like a plausible structural system. If they were smaller, they wouldn’t look believable. The largest beams mark the major divisions in the room. Reducing the size of the beams between them, as you would if they were real beams, has the added benefit of making all the intersections between beams simple butt joints, which are fast and easy to execute.
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