Manufacturer and supplier of roof products and accessories for the metal building industry since 1964

R-Panel Roof Curb

R-Panel Roof Curb

R-Panel Roof Curb (High Rib Roof Curb) fits any R-Panel metal roof system. Custom curb dimensions and configuration are built to meet any skylight or rooftop equipment requirements. Pitch correction to match roof slope as specified. Rib-to-rib (R&S Layover) side flanges come standard for a complete weather tight seal. Economical flat flange models are also available. Roof curb may include a custom finish that matches the roof color. Roof Curbs install under the roof panel on the up-slope and over the roof panel on the down-slope, which results in a shingled watershed condition for complete weather-tight condition. In addition, a 20-Year Warranty comes standard on all aluminum curbs.

Roof Curbs For: HVAC | Exhaust Fans | Skylights | Gravity Vents | Pipe Penetrations

  • Description
  • Model Guide
  • Sizes and Weights
  • Documents
  • Certification
  • FAQ
  • R&S Insights


Material 0.80 aluminum
18 GA, 14 GA or 16 GA Aluminized steel
1″ Rigid Insulation R6.5 (higher R-Values available)
Construction Full penetration welds, thoroughly tested
Mitered corners for true square top
Curb Up-slope Flange installs under panel
Panel closures welded or shipped loose
Integrated 4″ high water cricket
Min 9″ between up-slope curb wall and closures
Curb Down-slope Flange installs over panel
Caps (straps) welded or shipped loose
Minimum 3″ down-slope flange
Curb Side Flanges Rib-to-Rib, layover to next natural high rib
Minimum 3″ between curb sidewall and high ribs
Curb Top Level top when specified
Skylight curbs slope with roof
Dimensions 6″ – 8″ curb height on up-slope (custom heights available)
Finish Aluminum mill finish
Powder coat (standard colors)
Kynar (exact match)
Accessories 14 GA backer-channel
Sealants, fasteners
Certifications Engineering calcs (additional costs apply)
Warranty 20 Years (aluminum)
1 Year (steel)

TYPE IF CURB (Internally Flanged)

Same design / construction as above with the following exceptions:

Curb Up-slope Up-slope base flange breaks inward 1-1/2″
Includes 2-peice water diverter assembly and backer channel
Curb Down-slope Down-slope base flange breaks inward 1-1/2″
Integrated caps in curb wall accept panel highs
Curb Side Flanges Side base flanges break inward 1-1/2″
Backer Channel Integral backer channel Included with all IF curb kits


Curb Liner Conceals insulation, mill or white finish, complete kit for install
Ridge Mount Installs on ridge condition, double pitched
Collar Top Square-to-round transition
Over / Over Up-slope and Down-slope over roof panel
Non-Insulated Cost savings when insulation not required
High R-Value 2″ thick insulation for R14 value
Damper Shelf Damper support for exhaust fan
Duct Supports Blank-offs, duct supports for HVAC equipment

Curb Model Guide

Provide roof panel make, model, seam spacing and pitch when requesting quote

Model L
Side Flanges Closures/
Curb Top Insulation Material Finish Options (add all that apply)

R-Panel / High Rib

  • L: Layover
  • R: Flat Flange
  • F: Internally Flanged
1: Fixed / Welded

2: Loose / Field Located

3. None

4. Up-slope Flat, Down-slope Offset

  • U: Under / Over
  • O: Over / Over
  • L: Level
  • S: Slope w/ Roof
  • Y: Insulated
  • X: Not Insulated
  • A: Aluminum
  • G14: 14 Gauge Galvanized Steel
  • G16: 16 Gauge Galvanized Steel
  • G18: 18 Gauge Galvanized Steel
  • M: Mill
  • P: Powder Coat
  • K: Kynar
  • CL: Curb Liner
  • RM: Ridge Mount
  • CT: Collar Top
  • DS: Duct Supports


MBR-48x96x8-L1SY-18AM-CL: Metal building roof curb with outer dimension of 48″x96″ and 8″ high at the upslope curb wall. Features layover type side flanges with fixed / welded closures and caps and a non-pitched-corrected top flange. Fabricated of aluminum, mill finish and a curb liner (double wall).

R-Panel Roof Curb Terminology

  • Closure: seals trapezoidal panel at up-slope curb opening (under panel)
  • Cap: seals trapezoidal panel at down-slope curb opening (over panel)
  • Seam Clip Side Flanges (C): side flanges integrate with roof panel seams (includes seam clip)
  • Layover Side Flanges (L): side flanges extend and layover next natural high rib
  • Flat Side Flanges (R): flat side flanges 3″ typical
  • Internally Flanged (F): perimeter base flange breaks / seals inside curb wall
  • Under / Over: up-slope installs under, down-slope installs over roof panel
  • Over / Over (OO): up-slope and down-slope flanges install over roof panel
  • Floating 2-Curb System (FC): Inner weight-bearing curb and outer flashing curb (heavy equipment)
  • Ridge Mount (RM): Inner weight-bearing curb and outer flashing curb (heavy equipment)
  • Curb Liner (CL): white or mill finish liner on inside of curb wall; conceals insulationFloating
  • Collar-Top (CT): square-to-round transition for pipe penetrations

All curbs custom-sized to meet project specifications. CAD drawings are provided with each curb order (submittal package) including HVAC partitions, damper shelves and panel rib/seam contour placements.


Additional curb configurations available, call for details

Product Description Model Submittal Specifications Installation Warranty
Layover Side Flanges MBR-L PDF WORD PDF PDF
Flat Side Flanges MBR-R PDF WORD PDF PDF
Internally Flanged MBR-F PDF WORD PDF PDF
Collar Top Adapter
Square-to-Round Transition
Accessories Model Submittal Specifications Installation Warranty
Backer Channel
Layover Side Flanges
Backer Channel
Flat Side Flanges
Backer Channel
Internally Flanged Curbs

Additional Support Documents

Description Curb Type Roof Type Installation Guide
Downslope Loose Contour Internal Flange High Rib / R-Panel PDF
Curb Wall Section View Relevant to All Curb Types Relevant to All Roof Types PDF

Optional engineering calcs by Structural P.E. to ensure local codes and load tolerances are met.

What is the primary purpose of a standing seam roof curb?

Designed to fit trapezoidal or vertical standing seam roof panels, these curbs connect rooftop equipment to the roof.

What materials are commonly used for these curbs?

Common materials include aluminum or galvanized steel.

What are the insulation options with roof curbs?

These curbs come standard with 1″ rigid insulation, with options for higher R-Values available.

How does the roof curb’s construction ensure water doesn’t seep in?

The curbs are manufactured with full penetration welds and features like integrated 4″ high water crickets for effective water diversion.

Is there a warranty on these roof curbs?

Aluminum curbs come with a 20-Year Warranty, while Steel Curbs have a 1-Year Warranty.

R&S Insights Blog

Metal Building Roof Curb – How to Choose the Right Application

There are several choices to make when purchasing a metal building roof curb. Your evaluation should take into consideration the conditions on and around the roof… Learn More

What Are HVAC Roof Curbs and What Are They Made Of?

Commercial buildings often have at least one or a combination of these items on the roof: fans, condensers, skylights, hatches, vents, or AC units… Learn More

What Are Some Uses for Rooftop Curbs?

Roof curbs are used extensively on commercial roofs to ensure the safe installation and proper functioning of various components of the roof system, such as HVAC equipment, and more… Learn More


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R&S manufactures a vast array of products to fit your project needs. We aim to supply all of your metal building roof accessory needs, not just one product. Why go to multiple vendors when R&S can supply it all?