Roof Tech Inc., a leader in rail-less rooftop PV mounting systems, has added engineering to support 72-cell PV modules, or modules up to 21 sq. ft. The new engineering data was added to the company’s already extensive engineering reports created by Starling Madison Lofquist, Inc., a third-party firm that created the full reports from actual load testings. The simple to use tables are compliant with the IBC 2012, with values according to the roof zones, type of exposure and different attachment methods at different roof pitches and for top basic wind speed up to 180 mph and ground snow loads up to 113 psf.
RELATED: Mounting with butyl rubber: How Roof Tech gets a leak-proof seal
The PE reports include tables for rafter attachment (2”x 4”, 24” o.c.) and direct-to-the-roof decking (7/16” OSB and 15/32” Plywood thickness) applications that are not yet common to the U.S. PV industry. Roof Tech says direct-to-deck attachment is a true game changer and helps to lower the time on the roof dramatically. Unlike the common method of securing a PV system with lag bolts, Roof Tech’s approach uses multiple 5 mm stainless wood screws, making the roof decking installation evenly secured.
If the PV system needs to be secured to rafters, the overall installation becomes even easier to meet code because the 5 mm screw will need to hit within 60 percent from the center of the rafter. A 5/16” lag bolt will need to hit within 30% from the center of the rafter, which is a much narrower tolerance and therefore much more difficult to comply with the code.
At this time, only the E Mount AIR is being certified for the use of 72-cell modules, according to Roof Tech. For more information on Roof Tech or to download the new PE reports, visit Roof Tech’s website.
— Solar Builder magazine
[source: http://solarbuildermag.com/news/roof-tech-72-cell-residential-rail-less-mounting/]
Leave a Reply
You must be logged in to post a comment.