FX Rail-Less Engineering

FX Engineering & Design Guide
IRONRIDGE CONFIDENTIAL
Page 4 of 21
Exposure Category
Exposure category refers to the way obstacles protect buildings and the structures on top of
them from the force of wind storms. Therefore, based on your setting (urban, rural, or on flat
unobstructed terrain), you will design to one of the following Exposure Categories.
The majority of buildings in urban areas have an exposure category B.
Wind Exposure Category
Surface Roughness
Exposure B
Urban and suburban areas, wooded areas, or
other terrain with numerous closely spaced
obstructions having the size of single-family
dwellings.
Exposure C
Open terrain with scattered obstructions
having heights generally less than 30 feet.
This category includes flat open country and
grass-lands.
Exposure D
Flat, unobstructed areas and water surfaces.
This category includes smooth mud flats, salt
flats, and unbroken ice.
Risk Category
Structural performance of the FX System has been evaluated with ASCE 7-10 Risk Category II
loads (equivalent to ASCE 7-05 Occupancy Category II loads) resulting in the FX System
having the same structural integrity and reliability as the building it is deployed on.
2.2 Roof Considerations
Rafter Spacing
Rafter spacing must be established by surveying the building. This number impacts where you
can place attachments as you lay out your system.
The FX system can be installed on roofs with slopes of 9.5 to 45 degrees.
2.3 Module Compatibility
The FX system has been approved for use with the following PV modules. Unless otherwise
noted, “xxx” refers to the module power rating and both black and silver frames are included in
the certification.