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

Conventional / Built-up

Conventional / Built-up Roof Curb

Our conventional / built-up roof curbs feature full penetration continuous welds at all seams. We fabricate the curbs with a 3″ perimeter flat flange around the base of the curb, in addition to a 1.5″ x 1.5″ treated wood nailer to accept roofing material. Curb walls are finished with 1″ rigid insulation and may be fitted with an interior white liner. Additionally, higher R-Value insulation is available. We provide scaled CAD drawings with all orders.

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


Material 18 GA, 14 GA or 16 GA aluminized steel
1″ Rigid Insulation R7.2 (higher R-Values available)
Construction Full penetration welds, thoroughly tested
Mitered corners for true square top
Curb Base Flange 3″ perimeter base flange
Custom base flange available
Curb Top Level top when specified
Skylight curbs slope with roof
1.5″x1.5″ treated wood nailer
Dimensions 12″ height typical
1.5″ top flange
3″ perimeter base flange
Finish Galvanized steel mill finish
Certifications Engineering calcs (additional costs apply)
Warranty 1 Year


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
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 Insulated blank-offs, duct supports for HVAC equipment

Curb Model Guide

Model L x W x H Side Flanges Closures/
Insulation Gauge Material Finish Options (add all that apply)
Conventional Built-up or Membrane Roof
R: Flat Flange  NA L: Level

S: Slope w/ Roof

Y: Insulated

X: Not Insulated




B: Steel

C: Stainless Steel

NA CL: Curb Liner

RM: Ridge Mount

CT: Collar Top




Flat Side Flanges (R): flat side flanges 3″ typical
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.


Additional curb configurations available, call for details

Product Description Model Submittal Specifications Installation Warranty
Built-up / Membrane MBS-R PDF WORD PDF

Conventional Roof Curbs FAQ

What are conventional roof curbs?

Conventional roof curbs are raised metal platforms that offer support and weatherproofing, distributing the weight of rooftop equipment like HVAC units, exhaust fans, and skylights, and preventing damage to the roof membrane.

Can you list a couple types of conventional roof curbs?

Types of conventional roof curbs also called built-up roof curbs include Non-Ventilated Curbs for general equipment support, Ventilated Curbs with airflow vents, Curbs with Curbsticks for added stability, and Custom Curbs designed for specific needs and equipment dimensions.

What are built-up roof curbs made of?

Built-up roof curbs are most commonly made of galvanized steel for durability and weather resistance, but can also be made from aluminum or stainless steel for specific applications.

What are the benefits of conventional curbs?

The main benefits include enhanced weatherproofing, structural support for rooftop equipment, and simplified equipment installation. Conventional roof curbs provide a ready platform for mounting, streamlining the installation process and saving time and construction costs.

What are the advantages of using a custom roof curb?

Custom roof curbs offer a perfect fit for unique equipment and complex roof configurations, ensuring optimal performance and aesthetics.

R&S Insights Blog

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

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


Check out our Product Line Card

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?