RailFX RFXCB-3.1235-42-SI-AL-12S-FLP Aluminum Cable Braces (Stairs)

RailFX’s stair cable brace solves the angle problem that kills installation speed. Pre-slotted holes eliminate field drilling while maintaining the precise 3-1/8” cable spacing code requires. At 50 inches long with 12 slotted holes, one brace handles any stair run when trimmed to fit between your top rail and deck surface.

This aluminum brace targets contractors installing cable rails on stairs where posts sit 6 to 8 feet apart — exactly where cables start to sag without support. The 5/8” square profile keeps sight lines clean while the AAMA 2604 powder coat finish handles Montana’s temperature swings and UV exposure.

Pre-Engineered for Stair Angles

The slotted holes make this product. Traditional round holes force contractors to drill new ones when stair angles don’t match pre-drilled spacing. RailFX slots each of the 12 holes to accommodate standard stair angles without modification, while the 50-inch length (versus 42 inches on their level version) provides extra material for trimming to any top rail height.

That 3-1/8” (3.125”) on-center spacing hits the sweet spot for code compliance — close enough to prevent kids from getting through, far enough apart to minimize cable count and cost. Installation runs straightforward: position between posts, align slots with your cable path, cut to length, mount with the included floor plates (2 angled, 1 level), then thread cables through and tension.

Material and Finish Built for Mountain Weather

Extruded aluminum construction means no rust, no rot, no warping from freeze-thaw cycles. The silver anodized powder coat meets AAMA 2604 standards — real durability testing for color retention, chalk resistance, and adhesion. That matters when summer deck temps hit 140°F and winter drops below zero.

Specification	Value	Source
Material	Extruded Aluminum	Manufacturer
Profile	5/8” x 5/8” square	Manufacturer
Length	50 inches (trimmable)	Manufacturer
Holes	12 slotted	Manufacturer
Spacing	3-1/8” (3.125”) on-center	Manufacturer
Finish	Silver anodized/powder coat (AAMA 2604)	Manufacturer

The warranty backs up the quality claims: limited lifetime on the aluminum and powder coat finish against cracking, chipping, blistering, or peeling, plus 4 years prorated labor coverage if something fails.

System Compatibility and Code Compliance

This brace works with RailFX aluminum posts, wood posts, and composite-sleeved posts. Compatible across their entire cable line — Basic, Professional, FlexFX, and PFX1000 Series. The design exceeds IBC and IRC structural requirements when installed as part of a complete RailFX system.

Each kit includes the 50-inch pre-drilled aluminum tube, 2 angled floor plates for stair mounting, 1 level floor plate, and fastening screws. No hunting for compatible brackets or wondering about hole alignment.

The Verdict

Worth it for any contractor tired of drilling cable braces on site. The pre-slotted design saves real time on stair installations while the 50-inch length handles any residential top rail height. At 5/8” square, it adds minimal visual weight while preventing the cable sag that makes railings look sloppy and fail inspection.

For Montana’s multi-story mountain homes where 6-8 foot post spacing is standard, these braces deliver the structural support cables need without the field fabrication headaches. The AAMA 2604 finish holds up to actual weather, not just laboratory testing.

FAQ

What makes the slotted holes better than round holes for stairs?

Slotted holes accommodate varying stair angles without requiring new holes to be drilled on site. Round holes lock you into one specific angle — if your stairs don’t match, you’re drilling new holes in the field.

Can this brace be cut shorter if needed?

Yes. The 50-inch length is designed to be trimmed to fit between your specific top rail and deck surface or bottom rail.

What’s included with each brace?

The kit includes one 50-inch pre-drilled slotted aluminum tube, two angled floor plates for stair mounting, one level floor plate, and mounting screws.

What post spacing requires these braces?

These braces are designed for installations where posts are spaced 6 to 8 feet apart. Closer post spacing typically doesn’t need intermediate cable support.

How does the warranty work?

RailFX provides a limited lifetime warranty on the aluminum components and powder coat finish against cracking, chipping, blistering, or peeling. They also include 4 years of prorated labor warranty for replacement of defective parts.