Box Beams vs. Solid Beams: Understanding the Differences

Exposed wood beams add unmatched character and warmth to a space — but not all beams are the same. When designing with timber, you’ll typically choose between solid beams and box beams (also called “hollow beams”). Both create a stunning visual impact, but they are built differently and serve different purposes.

Solid beams are exactly what they sound like: a single, solid piece of wood, often reclaimed from historic buildings or milled from large, old-growth trees.

Authenticity: Nothing compares to the organic beauty, heft, and texture of a true solid beam.

Character: Especially in reclaimed materials, solid beams showcase deep, natural patina, weathered surfaces, and historical marks like mortise holes or saw cuts.

Strength: Solid wood offers natural structural strength and can be used both decoratively and structurally.

Weight: Solid beams are extremely heavy, requiring careful engineering and strong support during installation.

Best for: Projects where authentic character or load-bearing strength is critical.

Box beams are three or four planks of wood joined together to form a hollow “box” that looks identical to a solid beam once installed.

Lightweight: Being hollow, box beams are much lighter and easier to install, making them ideal for retrofits and ceilings without heavy structural support.

Versatility: They can be fabricated to any size, allowing for custom widths, lengths, and depths that might not be possible with solid timber.

Material Efficiency: Box beams can be made from reclaimed wood, using thinner boards while still showcasing the historic face.

Seamless Look: Skilled fabrication can hide joints completely, making box beams nearly indistinguishable from solid ones when viewed in place.

Best for: Decorative ceiling treatments, large spans without needing heavy reinforcement, or when installation logistics make solid beams impractical.

Using reclaimed wood for box beams allows you to achieve the antique look — patina, surface texture, nail holes — while minimizing the challenges of weight and movement that come with massive, old solid timbers.