24040092 - Thorman LetterWESTSHORE
DESIGN ENGINEERS, P.C.
100 GREAT OAKS BLVD. Ϳ SUITE 115
ALBANY Ϳ NEW YORK Ϳ 12203
WestShore Design Engineers ۅ 100 Great Oaks Blvd. ۅ Suite 115 ۅ Albany, NY 12203 ۅ 518.313.7153
Subject: Thorman Residence
34 Hockanum Rd.
Northampton, MA
Dear Trinity Solar,
The following references the Thorman Residence in Northampton, MA:
1. Existing roof framing:
Conventional framing is true 3x4 at 32”o.c. with a 6x6 beam at the midspan and a 9’-10” span
(horizontal rafter projection). This existing structure is capable to support all the loads that are
indicated below for this photovoltaic project.
2. Roof Loading:
- 4psf dead load (modules plus mounting hardware)
- 40psf ground snow load
- 5.7psf roof materials (1.7psf 2x6, 1.5psf sheathing, 2.5psf asphalt shingles)
- Exposure Category B, 140mph wind (3 sec.)
This installation design will be in general conformance to the manufacturer’s specifications, and complies
with all applicable laws, codes, and ordinances, specifically the International Building Code/IBC 2015
and International Residential Code/IRC 2015 including all MA regulations and amendments. The spacing
and fastening of the mounting brackets is to have a maximum of 48”o.c. span between mounting brackets
and secured using 5/16” diameter corrosive resistant steel lag bolts. To evenly distribute the load across
the roof rafters, there shall be a minimum of 2 mounting brackets per rafter & min. 3” penetration of lag
bolt per bracket, which is adequate to resist all 125mph wind live loads including wind shear. Per NDS
Section 11.1.4 clearance holes equal to the diameter of the shank need to be bored into primary a primary
framing member for the full length to the threaded portion of the screw to avoid splitting of the framing
member.
Thank you.
Westshore Design Engineers
4/5/2024
John Eibert Nicolas Nitti, PE
Project Coordinator President
To: Trinity Solar
4 Open Square Way #410
Holyoke, MA 01040
Date: April 5, 2024
Ref.: 24040092