Levi, Mara-EL REVNorthampton, MA March 25, 2022
212 Main St.
Northampton, MA 01060
Trinity Solar No.
67 Milton St 2022-03-679229
Northampton, MA 01062
RE: FIGUEROA-STARR, LEIGH E; LEVI, TAMARA E
Trinity Solar | 4 Open Square Way, Suite 410 | Holyoke, MA | (413) 203-9088
MA License No. 56687
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 true 2x6 at 24 o.c.; existing rafter span= 9' 0"; (horizontal projection)
Conventional roof framing at R3 is 2x8 at 16 o.c.; existing rafter span= 9' 0"; (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 - 40 psf - per ASCE Hazard Tool
• Wind criteria - Exposure Category B, 117 mph wind
3. Existing roof modification -none required; existing roof framing is acceptable for PV installation.
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 and fastening of the mounting brackets is a maximum of 48” o.c. between mounting brackets (staggered)
and is secured using 5/16” diameter corrosive-resistant steel lag bolts. A minimum of 2½” of penetration (embedment)
per lag bolt is required, which will resist all stated loads above – including wind shear. Per NDS Section 12.1.4,
clearance holes - equal to the diameter of the shank - need to be bored into a primary framing member for the
full-length of the threaded portion of the bolt to avoid splitting of the framing member.
Regards,
Ihor Bojcun, PE
Structural Engineer - Trinity Solar