Everhart, CJ- EL REVNorthampton, MA
212 Main St.
Northampton, MA 01060
139 Nonotuck St
Florence, MA 01062
MA License No. 56687
RE: HUBBELL, MADELEINE; EVERHART, CARLY J
Trinity Solar | 4 Open Square Way, Suite 410 | Holyoke, MA | (413) 203-9088
July 15, 2024
Trinity Solar No.
2024-05-1075718
To the Building Official:
The following information constitutes a summary of the relevant design criteria and recommendations for the support of a new photovoltaic
[PV] system on the existing roof framing components at the above-referenced location.
Criteria is as follows:
1.Existing roof framing:
Conventional roof framing at R1 is 2x6 at 16 o.c.; existing rafter span= 11' 3"; (horizontal projection)
2.Roof Loading:
• 3.0psf dead load (pounds per square foot - PV panels, mounting rails & hardware)
• 5.7psf - existing roof loads (1.7 psf - 2x6 framing, 1.5psf roof sheathing, 2.5 psf shingles)
• Ground Snow Load - 40psf - per AHJ (Authority Having Jurisdiction)
• Wind criteria - Exposure Category B, 117 mph wind
3. Existing roof modification at R1 - A 2x4 “strongback” (L-shaped profile of two 2x4s) to be installed in low height areas to achieve a
maximum span of 10' 8".
This installation design is in general conformance with the manufacturers’ specifications and complies with all applicable laws, codes, and
ordinances – specifically the International Building Code (2015 edition) and the International Residential Code (2015 edition), including all
Massachusetts regulations and amendments.
The spacing of the mounting brackets - the ClickFit Smart Foot and/or RockIt Smart Slide by EcoFasten® (or approved equal) - cannot
exceed a maximum of 48” o.c. between mounting brackets and will be fastened using #14x3" long (min.) lag screws per bracket (2 min.) for
a rail system or #12x3" long (min.) lag screws per bracket (2 min.) for a rail-less system. The minimum thread penetration (embedment) is
2½" beyond all roofing materials - this is adequate to resist all stated demand loads above, including wind shear. In order to evenly
distribute the PV load across the roof framing, in multi-row PV layouts there shall be a minimum of 2 mounting brackets per rafter/truss
chord. Pilot holes for EcoFasten self-drilling screws are not required.
Regards,
Ihor Bojcun, PE
Structural Engineer - Trinity Solar