Berenson, Ronald- EL REVFlorence, MA
212 Main St.
Northampton, MA 01060
1 High Meadow Road
Northampton, MA 01062
MA License No. 56687
RE: BERENSON, RONALD; BERENSON, HANNAH
Trinity Solar | 4 Open Square Way, Suite 410 | Holyoke, MA | (413) 203-9088
January 27, 2023
Trinity Solar No.
2022-11-794268
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:
Roof R1: Modular home roof framing is 2x6 at 24 o.c.; existing rafter span = 10' 8" (horizontal projection) with existing 2x6 collar ties
at all rafters at 1/3 of the ridge-eave height down from the roof ridge elevation; Lumber is MSR 2500FB 1.8E SPF as per information
provided by field crew personnel as discovered prior to installation
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
• Wind criteria - Exposure Category B, 115 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