HomeMy WebLinkAboutLETTER - 19-00416 - 980 Westwood Dr - Solar PanelsThursday, July 15, 2019
Empire Solar Group
3250 N 750 E Suite B, Layton, Utah 84041
Layton, UT 84041
RE: ROOF EVALUATION FOR 980 WESTWOOD DRIVE, REXBURG, ID 83440
As per your request I evaluated the support system for the proposed solar array for the residence located
at 980 Westwood Drive, Rexburg, ID 83440.
It is my understanding that the roof structure consists of pre-manufactured trusses at 24" o.c. where the
solar panels will be located. The area of roof that will experience additional weight from the solar panels is
2,941 square feet and will be supporting 16 solar panels covering an area of 281.7 square feet.
The following loads were used in the analysis.
Dead Load
Snow Load
44,115 lbs (15.0 psf design load)
147,050 lbs (50.0 psf design load)
Solar Panels 845 lbs (3.0 psf design load)
International Existing Building Code (IEBC) 2015 Section 807.4 indicates that alterations to a building that
result in less than 5% increase in the gravity loads may be performed without a structural evaluation of the
existing building. The proposed alteration to the required loading of the structure results in a 0.44%
increase over the current loading requirements, which is allowed by IEBC 2015.
International Existing Building Code (IEBC) 2015 Section 807.5 indicates that any existing lateral load-
carrying structural element whose demand-capacity ratio with the alteration considered is not more than
10% greater than is demand-capacity ratio with the alterations ignored shall be permitted to remain
unaltered. The proposed alteration to the required loading of the structure results in a 1.92% increase over
the current loading requirements, which is allowed by IEBC 2015.
It is my recommendation that the existing trusses will safely and adequately support the solar panels. The
roof attachments should be staggered such that the mounting hardware can be attached to each truss at
24" o.c. in order for the loads to be evenly distributed along the trusses. The racking should be installed
per the manufacturer's specifications directly to the truss top chords. epic Engineering assumes no
responsibility for improper installation of the solar panels. A representative from epic Engineering has not
physically observed the roof framing of this structure.
I can be reached at (435) 654-6600 with any questions.
Respectfully,
Adam Huff, S.E.
epic Engineering, P.C.
7/15/2019
Date: 7/15/2019
Page: 2 of 3
Date: 7/15/2019
Page: 2 of 3