The end of a beam is the last visual element the eye encounters before the beam disappears into the wall. A clean, well-designed termination feels intentional and resolved. A poorly handled end — a square-cut face that doesn't match the curve, a filler plug that doesn't quite fill the profile, a visible fastener — undermines the entire installation and makes the beam look like it was simply cut off.
For curved beams, the termination is more complex than for straight beams. A straight beam ends in a flat face at a defined angle. A curved beam ends in a surface that follows the beam's curve, and that surface has to transition to a flat termination plane — typically the wall. Getting that transition right requires a purpose-molded end cap.
What makes a curved end cap different
A straight beam end cap is essentially a flat face. You cut the beam to length, finish the end-grain, and apply a thin return trim if desired. The geometry is simple and the field work is manageable.
A curved beam end cap has to follow the beam's radius as it transitions to the wall plane. At the outer edge of the curve, the cap is widest; at the inner edge, it's narrowest. The transition surface between the beam's curved profile and the flat termination plane is itself curved.
The geometry can be handled as a gentle transition — a long, gradual blend from the beam's curve to the wall plane over 60–100 mm — or as a sharp transition — a short curve that closely follows the beam's profile before landing on the wall. Gentle transitions are easier to mount and forgiving of positioning errors. Sharp transitions look more refined and architectural but require more precision during installation.
Common termination scenarios
Wall termination
The most common scenario is a curved beam running into a flat wall. The cap lands on the wall surface, and the joint between the cap face and the wall is sealed with paintable urethane caulk.
The wall is rarely perfectly flat. In older buildings, walls bow inward or outward near corners — often by 3–5 mm over 300 mm, enough to create a visible gap at the cap joint. We address this by ordering the cap 3–5 mm oversized on the wall edge. The installer scribes the edge during fitting using a profile gauge, cuts to the scribe line, and achieves a tight fit even on uneven walls.
The scribe technique is straightforward: place the profile gauge against the wall at the cap position, transfer the wall contour to the gauge, then transfer the gauge to the cap edge and cut along the line with a jigsaw or rotary tool.
Column and pilaster termination
A curved beam terminating against a column or pilaster is handled with a wrap cap. The cap extends past the column face by 40–80 mm on each side, creating a shadow gap that anchors the beam visually to the column. The gap is filled with a black closed-cell backer rod and sealed with caulk, creating a uniformly dark line regardless of the column's surface condition.
Wrap caps are more complex to produce because they must follow two planes simultaneously: the front face of the column and the two side faces. We build wrap caps from the column's measured dimensions and the beam's geometry. The mold is custom for each project.
For very complex column profiles — round columns, fluted pilasters, tapered columns — we sometimes recommend a simpler approach: a flat wall cap that stops at the column face with a clean butt joint, plus a separate trim piece that wraps the column and meets the beam cap. This approach is more forgiving of dimensional variation in the column.
Ceiling termination
Curved beams can terminate against a flat ceiling beam, a soffit, or a structural member. The cap follows the beam's curve to the ceiling plane, and the joint is covered by a small trim piece that bridges the gap.
For ceiling terminations, we recommend ordering the ceiling trim and the end cap together so both pieces are engineered as a system. They are finished in the same color in the same session, and the joint between them is pre-finished in the factory.
The termination plane: choosing the angle
The angle of the termination plane relative to the beam axis determines how the cap reads against the wall.
Perpendicular to the wall is the most forgiving approach. The cap face sits flat against the wall, creating a clean vertical line that's easy to caulk. This is the standard for contemporary interiors.
Perpendicular to the beam axis is a traditional miter approach. The cap face is at the same angle as the beam's end-grain. This reads as a natural end to the beam and is common in classic and transitional interiors.
Custom angle is used for off-square wall junctions or intentional design angles. If a wall is more than 3 degrees out of square, a custom angle cap that matches the actual wall angle produces a cleaner result.
Material and production
Curved end caps are cast in high-density polyurethane to match the main beam. The curve profile is molded to continue the beam's curvature through the cap, so the joint between cap and beam is seamless.
The cap is finished in the same color and sheen as the main beam in the same production session. For multi-tone finishes, the cap is finished with the same layering sequence: base stain, grain wash, and glaze. The grain pattern continues across the joint; the cap edge may need a touch-up during installation to align the grain visually with the main beam.
Mounting sequence
Curved end caps mount with construction adhesive and a hidden mechanical fastener. The adhesive is applied to all contact surfaces between the cap and the beam. The fastener is a small stainless steel angle bracket that sits inside the beam, pre-painted in the beam color.
The mounting sequence:
- Test-fit the cap against the beam end and the wall. Confirm the scribe line if needed.
- Scribe and trim the wall edge of the cap if the wall is uneven.
- Apply construction adhesive to the contact surfaces.
- Slide the cap into position and press firmly against the wall.
- Hold for 30 seconds while the adhesive grabs.
- Insert the hidden fastener through a small access hole in the back of the beam.
- Secure the fastener and fill the access hole with a color-matched plug.
- Caulk the wall joint with paintable urethane caulk.
- Touch up any visible filler at the beam-to-cap joint.
The access hole for the fastener is typically 8–10 mm. For premium projects, the plug is hand-finished to blend perfectly with the surrounding surface.
Lead times and ordering
Custom curved end caps for standard beam profiles ship within 10 business days. For non-standard profiles or complex wrap geometries, lead time is 20–30 days from approved shop drawing.
Send the beam profile, the curve radius, the termination type (wall, column, or ceiling), and the wall angle if not perpendicular. We'll return a shop drawing, a sample cap, and a quotation within five business days.
For high-volume projects with many identical end caps — a hotel chain with the same curved beam detail in every property, or a residential developer building the same design across multiple units — we offer production optimization that reduces the per-cap cost significantly. The optimization involves grouping caps from multiple units into a single production run, reducing setup time and mold amortization. Contact our trade desk for volume pricing.
For unique ceiling projects where the end cap geometry is non-standard — a beam terminating at a compound angle, for example — we offer a design development service that works with the architect to resolve the geometry before production begins. The service includes a 3D-printed prototype cap for on-site fit verification before the production mold is committed.
For projects requiring the cap to integrate with electrical or plumbing services — a beam that conceals a downlight, a junction box, or a small-diameter pipe at its termination — we can machine a service opening in the cap. The opening is reinforced with an internal collar that maintains the cap's structural integrity and is positioned to align with the service location on the wall. We supply a cover plate finished to match the cap for clean access.
Technical References
ASTM standards cited in every specification
Test Data
Lab results from internal testing program
Updated 2026
Reviewed against current product specs
