Common Rooftop Curb Types Explained & Defined!
When placing a new Rooftop Unit on a curb, you have so many choices. So I’ve assembled a summary of the most common curbs, and I’ll explain what differentiates them.
Knockdown Curb – This curb ships unassembled, and can be easily stored in your inventory. It’s an inexpensive option, and with the use of some basic tools, it’s very easy to field assemble!
Welded Curb – This curb saves time in the field since it ships fully assembled, but the welded construction is more expensive to ship, and some times requires a crane to get it onto the roof, and into place.
Adjustable Pitch – The MicroMetl Adjustable Pitch Curb is designed to pitch up to one in twelve inches in either direction. The adjustable pitch curb ships knockdown, is less expensive than a fixed pitch welded curb, and allows job-site flexibility.
Platform Curb – This curb type has an insulated metal covering, standard wood nailer, and is intended to support horizontal rooftop units, split system condenser sections, or similar type items. It can be roofed in, or fastened to a concrete slab.
Horizontal Curbs – It accepts a down discharge RTU, and redirects the air flow out the side(s), or end(s) of the curb, converting it into a horizontal application.
Structurally Calculated Curbs – There will be times when the building code will call for a calculated, or seismic rated roof curb that is approved and stamped by a Professional Engineer. These requirements are often based upon the California Building Code, and International Building Code.
Vibration Isolation Curbs – The Isolation Curbs contain strong steel springs with a two inch deflection. They are designed and engineered to control noise and vibration of packaged, curb-mounted mechanical equipment from the roof structure.
The Wind Curb – Built to secure the rooftop unit to the curb in high wind conditions. They gained recognition following the devastation of South Florida from Hurricane Andrew. The wind curb is PE Stamped and requires field anchoring.
Metal Roof Curbs– Designed for metal ribbed roofs. This curb will always require a pitched construction, and does not contain a full perimeter wood nailer. Instead, the Metal Roof Curb remains exposed, and requires additional sealing upon installation.