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All Rooftop Air Handling Units generate noise and vibration. The built in "internal spring isolators" are difficult to adjust, so quite often the fan is left sitting on the shipping blocks. If a 250 pound mechanic manages to squeeze through the 2 X 4 ft. access opening, and execute the graceful ballet movements to reach and adjust the springs, the turbulent air flow passing through the unit still continues to excite the sheet metal housing. The sheet metal curb continues the path into the building.

The situation is even more sensitive when the architect's require keeping the equipment out of view. This moves the roof unit away from the more rigid exterior and places it in the most flexible central part of the roof, following the old adage, "The more noise and vibration equipment generates the most likely it will end up over executive office space or bedrooms".  Our Mounted Aluminum Base (CMAB) incorporates springs that need no adjustments. It is an excellent way of isolating this noise and vibration. As you can see from our pictures of a recent installation, the CMAB is easy to install as it caps the curb.

Assembled CMAB installed on Curb, ready to receive the complete Unit lowered by the Crane.

In most cases it is fully assembled. If exceptionally large or includes a pipe chase extension, as the unit shown in the photos, it needs to be in sections with a maximum length of 20', joined together with our splice kits. Whether the unit is broken down or not, we never supply a box of junk that requires extensive assembly at the site and ends up looking amateurish. Corners are mitered and welded and the springs are placed and secured between the upper and lower aluminum sections at our facility. The EPDM weather-seal connecting the upper and lower extruded aluminum members is installed here. The unitized construction makes this weather-tight installation quick and easy.

In contrast, most cheaper or "equal" curb mounted bases are sent to the project in boxes which leaves the contractor feeling like a dad on Christmas morning reading "Some assembly required". The Contractor must place the springs between the upper and lower portions at the correct locations and crimp in the weather seal. Corners are butted and caulked in the field. One can only imagine the leaks and service problems. That is not our way.

Our CMAB sales are increasing which means that the industry not only recognizes the value of a quiet building, but also understands that a properly designed and constructed curb is worth the price differential (Good no cheap, Cheap no good), and saves everyone a lot of money and aggravation in the long run. We limit our CMAB to 1" deflection due to the 1-3/4" width of the typical sheet metal roof top curb. This prevents our supplying taller, higher deflection springs which would be unstable at the narrow width.


For projects that require more deflection or in high seismic risk areas, we would recommend our Roof Spring Curb, "RSC". We are pleased to include our standard specifications for both products.



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