Metal Building Roof Curbs

by Mark Robins | 1 March 2022 12:00 am

Metal Building Curb Materials

Metal building roof curbs are constructed out of three primary materials: galvalume, aluminum and stainless steel. Galvalume is the most widely used material in the construction of metal building roof curbs. Galvalume is a carbon steel panel hot dipped in a protective coating of zinc, silicone and a high percentage of aluminum. Galvalume is durable and corrosion resistant.

The next most common material is aluminum. If a 20-year weathertightness warranty is required, the curb must be constructed out of 0.08-inch aluminum. Other elements in the curb design will also be required for the metal building curb to comply with this warranty.

Stainless steel has the highest material cost and is the more labor-intensive material to work with. For these reasons, very few metal building curbs made from stainless steel.

Types of Roof Curbs

There is a wide variety of roof curbs available. Here is a general list of the types of curbs available:

• Single metal building curbs
• Double metal building curbs; typically for RTUs more than 1,500 pounds
• Square to round pipe penetration curbs
• Transition/adapter curbs
• Seamed-in style curbs
• Custom roof access hatches (for equipment removal)
• Platform curbs
• Equipment rails
• Correctional facility security curbs

As you can see there are a variety of different applications and metal building curbs available. But what are the basic elements of their construction?

1. Curb flanges: front, side and rear
2. Curb side walls
3. Cricket/water diverter
4. Curb wall insulation
5. Metal ribs
6. Other miscellaneous items: gasket, mastic, fasteners

Curb Ordering Information

The specifications or construction details for your curbs may be provided on the drawings for your building. There will be some information that you will need to provide to the curb manufacturer for them to be able to produce your curb.

• Is there a specific material required? Galvalume, aluminum or stainless steel
• Is a 20-year weathertightness warranty required? Aluminum construction will be required for a 20-year weather tightness warranty.
• What is the metal building curb being used for? (If being used for heavy equipment over 1,500 pounds, a double structural curb will be required or recommended.)
• What is the slope of your roof?
• What is the outside dimension (OD) of your curb? Width by length (or provide the manufacturer and model # of the equipment being mounted to the curb.)
• What is the minimum height you need the curb to be on the high side of the roof?
• Who is your roof panel manufacturer?
• What is the roof panel name and seam spacing?
• If the curb is to be painted, who is the paint manufacturer and what color is the panel? Paint samples may be required to match the color. (If Kynar is required this can only be applied to aluminum and not all curb manufacturers have the capability to provide this finish.)
• Do you want welded ribs or loose ribs? Twenty-year weathertightness warranty curbs will have rib-to-rib construction.
• Do you require floating frame supports? This is required to allow the roof curb to move with the standing seam roof panels. Fixed frame supports will be supplied for screw-down R-Panel roof systems.

Ordering a metal building curb will involve collecting the above information. However, you won’t regret spending the small amount of time needed to put this information together and getting the correct curb for your project.

Chris Lafferty is general manager of Design Components Inc., Fayetteville, Ga. Design Components is a national distributor of metal building components, including doors and windows, canopies, pipe and roof flashing, roof curbs and hatches, skylights and smoke vents, ventilation products, ladders, METALWALK and S-5! Snow Retention Systems. To learn more, visit www.designcomponents.com[1] or email chris@designcomponents.com[2].

Source URL: https://www.metalconstructionnews.com/articles/metal-building-roof-curbs/

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