Flat-Flange Curb System

Flat-Flange curbs offer great flexibility for new and retro-fit applications. For roofs with panels out of modulation*, loose rib caps and plugs can offer a good option. RCS will not recommend rubber, polypropylene-based, or ABS plastic rib covers as the fasteners can too easily cut into the cap base. We exclusively offers aluminum rib caps & plugs designed for specific roof panel types with custom developed dies to ensure long-term weather-tightness** and durability. 

Flat-Flange curbs are available with loose High-Rib Caps and Plugs standard with optional integrated/welded High-Rib Caps and Plugs available at request.

RCS offers a specific TRAC Rail™ sub-framing for Flat Flange curbs to ensure critical curb/panel connections are properly supported while maintaining the dynamics of metal buildings.  The appropriate TRAC Rail™ product will be provided depending on your Panel Elevation or Roof Clip height.

SC TRAC Rail_Single Span_Standard.jpg

The Flat-Flange Roof Curb Package includes the following for a complete installation:

  • TRAC Rail™ for Flat-Flange Curb
  • Flat-Flange Curb fabricated to coordinate with the building roof slope and specific rooftop equipment
  • Mastic and Tube Sealant
  • Fasteners
  • Closures

Roof Curb Specifications:

  • Material: .063 or .080 Aluminum; 18-Gauge AZ55 available upon request
  • Insulation: 1-1/2” Commercial Board Fiberglass with R-6.5 thermal rating
  • CNC Punching and Burning fabrication processes deliver the most accurate nested metal parts
  • Configurator driven fabrication optimizes Forming processes to reduce welds and increase curb strength
  • Digital Wave Pulse welding technology delivers superior and consistent penetrating welds when combining Aluminum parts
  • All curbs are available in custom color paint to match your painted roof if desired

*When using curbs with welded rib caps and plugs special attention must be given to roof curb sub-framing location. If the roof panels are not in perfect modulation, welded on rib caps and plugs may not be the best choice.

**RCS will not offer an over/over installation due to elementary building science principles that have consistently proven the premature and rapid deterioration of the perpendicular up slope panel/curb connection due to exposure to ice and water.


How to install the Flat-Flange Curb System