Harrison LetterWESTSHORE
DESIGN ENGINEERS, P.C.
6279 JOHNSTON RD.
ALBANY Ϳ NEW YORK Ϳ 12203
WestShore Design Engineers ۅ 6279 Johnston Rd. ۅ Albany, NY 12203 ۅ 518.313.7153
Subject: Harrison Residence
589 Coles Meadow Rd.
Northampton, MA
Dear Trinity Solar,
The following references the Harrison Residence in Northampton, MA:
1. Existing roof framing:
Conventional framing is 2x10 at 16”o.c. with a 22’ max. 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
- 6.9psf roof materials (2.9psf 2x10, 1.5psf sheathing, 2.5psf asphalt shingles)
- Exposure Category B, 125mph 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
7/22/2024
John Eibert Nicolas Nitti, PE
Project Coordinator President
To: Trinity Solar
4 Open Square Way #410
Holyoke, MA 01040
Date: July 22, 2024
Ref.: 24070543