HomeMy WebLinkAboutEngineers Letter.pdfSeptember 5, 2013
Unirac
1411 Broadway Boulevard NE
Albuquerque, New Mexico 87102-1545
TEL: (505) 242- 6411
FAX: (505) 242-6512
Attn.: Engineering Department,
Re: Engineering Certification for the Unirac RM Roof Mounted Ballasted Photovoltaic Panel Support System.
The Unirac RM Roof Mounted Ballasted Photovoltaic Panel Support System is a proprietary framed ballasted assembly
which supports Photovoltaic panels. The ballast frames hold the PV panels and are ballasted with concrete blocks as
required for the wind loads. The wind uplift loads are resisted directly by the ballast. Lateral forces, both wind and
seismic, are resisted by friction between the ballast and the roof surface.
The ballasting requirements are determined using the Unirac online “U-Builder” Design Assistant tool or the
Unirac “Design and Engineering Guide”. The Design Assistant covers a wide range of system configurations and
loading and allows the user to customize the input to match the specific project conditions.
We have reviewed the Unirac RM Roof Mounted Ballasted Photovoltaic Panel Support System, the RDWI wind tunnel
test results and the Unirac ballasted system design methodology and have determined that the Unirac RM ballasted system
design methodology is a rational approach and is in compliance with the structural requirements of the following
Reference Documents:
Codes: ASCE/SEI 7-05 and ASCE/SEI 7-10 Minimum Design Loads for Buildings and other Structures
International Building Code, 2009 & 2012 Editions
California Building Code, 2010 & 2013 Editions
Other: Aluminum Design Manual, 2010 Edition
RWDI Wind Pressure Study Report #1300856
This letter certifies that the Unirac RM Roof Mounted Ballasted Photovoltaic Panel Support System, the Unirac online
“U-Builder” Design Assistant tool and the Unirac “Design and Engineering Guide” are in compliance with the
above Reference Documents.
Please feel free to contact me at your convenience if you have any questions.
Sincerely,
Paul Zacher, SE - President