Fixed Gap Boards

What is open joint cladding?

Open joint cladding is a facade system where boards are fixed with a deliberate, consistent gap between them rather than sitting flush against each other. Knotwood’s Fixed Gap Board maintains that gap precisely along the full run, creating a structured, contemporary look that is a clear step away from close-fitted cladding. The open joint is a recognizable feature of architect-led contemporary residential and commercial builds across the U.S.

What is the difference between open joint cladding and standard cladding?

In a standard close-fitted cladding system, boards butt together or interlock to create a continuous surface with no visible gap. Open joint cladding deliberately maintains a consistent space between boards. This changes the visual character of the facade, the drainage and ventilation behavior behind the cladding, and the way the system is fixed. Knotwood’s Fixed Gap Board is engineered to hold that gap consistently as the building moves through temperature and humidity cycles.

Does open joint cladding provide drainage and ventilation benefits?

Yes. The consistent gap in a Fixed Gap Board system allows moisture that penetrates the outer face to drain clear rather than sit against the substrate. It also allows airflow behind the cladding. For architects specifying in rainscreen wall situations, this drainage and ventilation behavior is a functional consideration alongside the visual one.

What is Fixed Gap Board cladding suited to?

Fixed Gap Board suits contemporary residential and commercial facades where a structured, open-joint look is part of the design brief. It is particularly common on architect-led projects where deliberate material detailing is central to the design language. It also works well paired with a close-fitted cladding profile like Classic Boards elsewhere on the same facade, with the open-joint section acting as a considered contrast to the solid surface.

What is visible behind open joint cladding boards?

Because the boards sit with a gap between them, the substrate or cavity behind the cladding is partially visible at certain angles. The appearance of a fixed gap facade depends on what sits behind: a dark-colored substrate or cavity batten will recede visually and emphasize the board profile, which is a common approach in contemporary facade design.

What sits behind matters as much as the board itself, so it is worth deciding early rather than leaving it to the installer. The cavity battens, the weather barrier and any insulation face will all be partially visible through the joint, and the substrate has to suit the exposure as well as the look. Send us the wall build-up and our team will confirm what works behind this profile.

What size is Fixed Gap Board available in, and how is it installed?

Fixed Gap Board comes in a single 6 inch size with a fixed 5/8 inch gap between boards, supplied in standard 18 foot 6 inch lengths. It uses a tab-lock fixing system: each board hooks onto a Tab-Lock Starter (KECTS) at the base and swings flush against the substructure, secured with a concealed Cladding Clip (KACC). Installation works from the bottom up, with Base Trim (F) and Cover Trim (M) closing the perimeter and Reversible Corner Trims finishing internal and external corners. Like Castellated Boards, Fixed Gap Board can also be installed vertically using the same system in a left-to-right sequence.

What finishes are available for Knotwood Fixed Gap Board cladding?

Fixed Gap Board is available in traditional solid powder coated colors or a sublimated wood grain surface. On an open joint facade the board edge is visible as well as the face, so the finish reads on two surfaces rather than one, which changes how a wood grain pattern looks across the run. The current U.S. range is set out on our finishes page.

What material is Fixed Gap Board made from?

Fixed Gap Board is made from 6063 T6 temper extruded aluminum alloy, sourced and produced in the United States.

What warranty does Knotwood offer on Fixed Gap Board?

Backed by a standard 15-year warranty and up to 25 years on selected finishes. See our warranty page for the terms that apply to this profile.

Is Fixed Gap Board fire rated?

Aluminum is non-combustible under ASTM E136, so the board does not contribute fuel to a fire. Compliance is never assessed on the cladding alone, though. The complete wall system, including framing, weather barrier, insulation, fasteners and cavity protection, has to be tested or assessed as a code-compliant assembly under the applicable I-Code as adopted by your jurisdiction. Send us the applicable code and the wall build-up and our team will confirm what test evidence is available for this profile.