Azzoni StructuralTo:ReVision Energy
7 Commercial Drive
Brentwood, NH 03833
Subject:Structural Certification for Installation of Solar Panels
Azzoni Residence
5 Fort Street
Northampton, MA. 01060
To Whom It May Concern,
The spacing of the solar standoffs should be kept at 48" o.c. or less with a staggered pattern to ensure proper
distribution of loads.
I further certify that all applicable loads required by the codes and design criteria listed below were applied to the
Ironridge solar rail system and analyzed. Furthermore, the installation crews have been thoroughly trained to install the
solar panels based on the specific roof installation instructions developed by Ironridge for the racking system and
Ecofasten for the roof connections. Finally, I accept the certifications indicated by the solar panel manufacturer for the
ability of the panels to withstand high wind and snow loads.
September 23, 2020
A design check for the subject residence was done on the existing roofing and framing systems for the installation of
solar panels over the roof. From a field inspection of the property, the existing roof support structures were observed by
the client's auditors as follows:
The roof structure of (MP1) consists of composition shingle (replacing existing slate tiles) on 1x wood decking. The wood
decking is supported by true dimensioned old growth 2x4 rafters at 30" o.c., paired with raised ceiling joists to create a
semi-vaulted ceiling. The rafters are butt joined at the peak, and are supported by load bearing walls at the eave.
The roof structure of (MP2) consists 2 layers of composition shingle on plywood sheathing. The plywood sheathing is
supported by 2x6 rafters at 32" o.c., detected by non destructive probing test. The total horziontal span of the roof is
approximately 12'-0", with a load bearing wall at mid roof to provide intermediate support to the rafters. Therefore, the
max horizontal span of the 2x6 rafters is 6'-0", with a slope of 19 degrees.
The roof structure of (MP3) consists of 1 layer of composition shingle on plywood sheathing that is supported by nominal
2x6 rafters at 16" o.c.. The rafters support a vaulted ceiling and have a max horizontal span of 5'-6", with a slope of 29
degrees. The rafters are connected to a ridge beam at the peak, and are supported by the exterior load bearing wall at
the eave.
The existing roof framing system of (MP1) is judged to be adequate to withstand the loading imposed by the installation
of the solar panels. No reinforcement is necessary.
The existing roof framing system of (MP2) is judged to be adequate to withstand the loading imposed by the installation
of the solar panels. No reinforcement is necessary.
The existing roof framing system of (MP3) is judged to be adequate to withstand the loading imposed by the installation
of the solar panels. No reinforcement is necessary.
Azzoni Residence, Northampton 1
Design Criteria:
●Applicable Codes = Massachusetts Residential Code, 9th Edition, ASCE 7-12, and 2015 NDS
●Roof Dead Load = 7 psf (MP1) -- 9 psf (MP2) -- 11 psf (MP3)
●Roof Live Load = 20 psf
●Wind Speed = 117 mph, Exposure B
●
Sincerely,
Elaine Huang, P.E.
Project Engineer
Ground Snow Load = 40 psf - Roof Snow Load = 35 psf
Please contact me with any further questions or concerns regarding this project.
Azzoni Residence, Northampton 2
40 psf
(ASCE7 - Eq 7-1)
1 (ASCE7 - Table 7-2)
1.1 (ASCE7 - Table 7-3)
1.1
35.0 psf
(ASCE7 - Eq 7-2)
1
35.0 psf
3.00
3.00
0.89
0.00 (Ceiling Not Vaulted)0.117.0 psf
8.4 psf
6.00
2.000.86
0.00 (Ceiling Not Vaulted)0.149.0 psf
9.52
3.00
2.001.72
4.000.2811.0 psf
12.58DL Adjusted to 29 Degree Slope
ps = Cspf
ps = Sloped Roof Snow Load =
pf = Flat Roof Snow Load =
Roof Snow Load Calculations
pg = Ground Snow Load =
Miscellaneous
1x Decking
Vaulted Ceiling
Ce = Exposure Factor =
pf = 0.7 Ce Ct I pg
Ct = Thermal Factor =
I = Importance Factor =
Cs = Slope Factor =
Roof Dead Load (MP1)
Composition Shingle
Roof Dead Load (MP3)
Roof Plywood
Vaulted Ceiling
2x4 Rafters @ 30"o.c.
2x6 Rafters @ 32"o.c.
MiscellaneousTotal Roof DL (MP2)
Total Roof DL (MP1)
Roof Dead Load (MP2)
Composition Shingle
DL Adjusted to 34 Degree Slope
DL Adjusted to 19 Degree Slope
Gravity Loading
MiscellaneousTotal Roof DL (MP3)
PV Dead Load = 4 psf (Per catalog)
Roof Plywood
Composition Shingle
2x6 Rafters @ 16"o.c.
Vaulted Ceiling
Azzoni Residence, Northampton 3
Per ASCE 7-12 Components and Cladding
117 mph
BGable/Hip34 degrees
20 ft40 ft
17.5 ft
(Eq_30.3-1)0.7 (Table 30.3-1)
1 (Fig. 26.8-1)0.85 (Table 26.6-1)
117 mph
1 (Table 1.5-1)qh = 20.85
Zone 1 Zone 2 Zone 3 Positive
GCp =-0.90 -1.10 -1.10 0.85 (Fig. 6-11)
Uplift Pressure =-18.77 psf -22.94 psf -22.94 psf 17.7 psf X Standoff Spacing =4.00 4.00 4.00
Y Standoff Spacing =2.75 2.75 2.75
Tributary Area =11.00 11.00 11.00Footing Uplift =-206 lb -252 lb -252 lb
-252 lb
400 lbTherefore, OK
Fastener =1 - 5/16" dia Lag
Number of Fasteners =1
Embedment Depth =2.5Pullout Capacity Per Inch =205 lb NDS Eq 12.2-1)
Fastener Capacity =513 lb NDS Eq 11.3-1)
w/ F.S. of 1.0 =513 lbTherefore, OK
Embedment Depth Reduction Factor 1
Lateral Force From Gravity Loads 215
Attachment Lateral Capacity 288 (NDS Table 12K)
Therefore, OK
Fastener Uplift Capacity Check
Fastener Shear Capacity Check
513 lb capacity > 252 lb demand
Input VariablesWind Speed
Effective Wind Area
Design Wind Pressure Calculations
Roof Shape
Building Least Width
Roof Slope
288 lb capacity > 216 lb demand
Wind Calulations
Standoff Uplift Capacity =400 lb capacity > 252 lb demand
Kz (Exposure Coefficient) =
Kzt (topographic factor) = Kd (Wind Directionality Factor) =
V (Design Wind Speed) =
I Importance Factor =
qh = 0.00256 * Kz * Kzt * Kd * V^2 * IWind Pressure P = qh*(G*Cp)
Exposure Category
Mean Roof Height
Standoff Uplift Calculations
Standoff Uplift Check
Maximum Design Uplift =
Azzoni Residence, Northampton 4
PASS
Dead Load 8.4 psfPV Load 4.0 psf
Snow Load 35.0 psf
Governing Load Combo = DL + SLTotal Load 47.4 psf
Fb (psi) =f'b x Cd x Cf x Cr (NDS Table 4.3.1)975 x 1.15 x 1.5 x 1.15
Allowed Bending Stress = 1934.1 psi
(wL^2) / 8
=726.479 ft#
=8717.75 in#
Actual Bending Stress = (Maximum Moment) / S
= 1634.6 psi
L/180 (E = 1500000 psi Per NDS)=0.466 in
Deflection Criteria Based on =(5*w*L^4) / (384*E*I)=
=L/210 <L/180 Therefore OK
Allowed Deflection (Live Load) =L/240
0.35 in(5*w*L^4) / (384*E*I)
L/284 <L/240 Therefore OK
Member Area =Fv (psi) =150 psi (NDS Table 4A)Allowed Shear = Fv * A /1.5 =Max Shear (V) = w * L / 2 =415 lb
Check Bending Stress
2x4 Rafters @ 30"o.c.
Member Span = 7' - 0"
8.0 in^2
Check Shear
w = 119 plf
(True Dimensions)
800 lb
Allowed > Actual -- 51.9% Stressed -- Therefore, OK
HF#1 Member Spacing@ 30"o.c.
Maximum Moment =
Check Deflection
I (in^4)10.67 Lumber Sp/Gr
Actual Deflection (Live Load) =
Allowed Deflection (Total Load) =
Actual Deflection (Total Load) =
Allowed > Actual -- 84.6% Stressed -- Therefore, OK
Member Properties
Member Size2x4 S (in^3)5.33
Framing Check (MP1)
Simple Span
0.401 in
0.296 in
Azzoni Residence, Northampton 5
PASS
Dead Load 9.5 psfPV Load 4.0 psf
Snow Load 35.0 psf
Governing Load Combo = DL + SLTotal Load 48.5 psf
Fb (psi) =f'b x Cd x Cf x Cr (NDS Table 4.3.1)875 x 1.15 x 1.3 x 1
Allowed Bending Stress = 1308.1 psi
(wL^2) / 8
=582.223 ft#
=6986.68 in#
Actual Bending Stress = (Maximum Moment) / S
= 923.9 psi
L/180 (E = 1400000 psi Per NDS)=0.4 in
Deflection Criteria Based on =(5*w*L^4) / (384*E*I)=
=L/554 <L/180 Therefore OK
Allowed Deflection (Live Load) =L/240
0.3 in(5*w*L^4) / (384*E*I)
L/766 <L/240 Therefore OK
Member Area =Fv (psi) =135 psi (NDS Table 4A)Allowed Shear = Fv * A/1.5 =Max Shear (V) = w * L / 2 =388 lb
(True Dimensions)
w = 129 plf
2x6 Rafters @ 32"o.c.
Member Span = 6' - 0"
Member Properties
Member Size S (in^3)I (in^4)Lumber Sp/Gr Member Spacing2x67.56 20.80 SPF#2 @ 32"o.c.
Check Shear
8.3 in^2 743 lb
Allowed > Actual -- 52.3% Stressed -- Therefore, OK
Check Bending Stress
Maximum Moment =
Allowed > Actual - 70.7% Stressed -- Therefore, OK Check Deflection
Allowed Deflection (Total Load) =
Actual Deflection (Total Load) =
Actual Deflection (Live Load) =
Framing Check (MP2)
Simple Span
0.094 in
0.130 in
Azzoni Residence, Northampton 6
PASS
Dead Load 12.6 psfPV Load 4.0 psf
Snow Load 35.0 psf
Governing Load Combo = DL + SLTotal Load 51.6 psf
Fb (psi) =f'b x Cd x Cf x Cr (NDS Table 4.3.1)875 x 1.15 x 1.3 x 1.15
Allowed Bending Stress = 1504.3 psi
(wL^2) / 8
=260.034 ft#
=3120.4 in#
Actual Bending Stress = (Maximum Moment) / S
= 412.7 psi
L/180 (E = 1400000 psi Per NDS)=0.366 in
Deflection Criteria Based on =(5*w*L^4) / (384*E*I)=
=L/1347 <L/180 Therefore OK
Allowed Deflection (Live Load) =L/240
0.275 in(5*w*L^4) / (384*E*I)
L/1942 <L/240 Therefore OK
Member Area =Fv (psi) =135 psi (NDS Table 4A)Allowed Shear = Fv * A/1.5 =Max Shear (V) = w * L / 2 =189 lb
w = 69 plf
2x6 Rafters @ 16"o.c.
Member Span = 5' - 6"
Member Properties
Member Size S (in^3)I (in^4)2x6
(True Dimensions)
8.3 in^2
7.56 20.80 SPF#2 @ 16"o.c.
Check Bending Stress
Maximum Moment =
Check Shear
743 lb
Allowed > Actual -- 25.5% Stressed -- Therefore, OK
Actual Deflection (Live Load) =
Lumber Sp/Gr Member Spacing
Framing Check (MP3)
Simple Span
0.049 in
0.034 in
Allowed > Actual - 27.5% Stressed -- Therefore, OK Check Deflection
Allowed Deflection (Total Load) =
Actual Deflection (Total Load) =
Azzoni Residence, Northampton 7