solar calcINSIGHT SOLAR
89 MARKET ST
NORTHAMPTON, MA 01060
Attn.: To Whom It May Concern
re job:SALUS RESIDENCE
84 RIDGEWOOD TERRACE
NORTHAMPTON, MA 01060
Design Criteria:
Code:2015 IBC w/ 780 CMR
ASCE 7-10
Live Load:20 psf
Ult Wind Speed:117 mph
Exposure Cat:B
Ground Snow:40 psf Min Roof Snow:30
Current Renewables Engineering Inc.
Professional Engineer
info@currentrenewableseng.com
8/25/2020
The following calculations are for the structural engineering design of the photovoltaic panels and are valid
only for the structural info referenced in the stamped plan set. The verification of such info is the
responsibility of others.
After review, I certify that the roof structure lacks sufficient structural capacity for the applied PV loads. See
the following calculations and Plan Sheets for upgrade details to bring the roof structure up to the required
All mounting equipment shall be designed and installed per manufacturer's approved installation
specifications.PR REOEFE NIS GSNIOE N LA
OF M H ATLSASEA
CW
HN
UOSMETMTOSCAMN IERDAOGHUT
HEAMNO. 53873
Exp: 6/30/2022
Date :8/25/2020
Job Code: SALUS RESIDENCE
2 of 6
Roof Properties:
Roof Type =
Roof Pitch (deg) =
Mean Roof Height (ft) =
Attachment Trib Width (ft) =
Attachment Spacing (ft) =
Framing Type =
Framing Size =
Framing OC Spacing (in.) =
Section Thickness, b (in.) =
Section Depth, d (in.) =
Section Modulus, Sx (in.^3) =
Moment of Inertia, Ix (in.^4) =
Framing Span (ft) =
Deflection Limit D+L (in.) =
Deflection Limit S or W (in.) =
Attachments Pattern =
Framing Upgrade =
Sister Size =
Wood Species =
Wood Fb (psi) =
Wood Fv (psi) =
Wood E (psi) =
CD (Wind) =
CD (Snow) =
CLS =
CM = Ct = CL = Ci =
CF =
Cfu =
Cr =
F'b_wind (psi) =
F'b_snow (psi) =
F'v_wind (psi) =
F'v_snow (psi) =
M_allowable_wind (lb-ft) =
M_allowable_snow (lb-ft) =
V_allowable_wind (lbs) =
V_allowable_snow (lbs) =
E' (psi) =
854
1400000
2181
1188
155
3034
1730
216
1.15
2407
1.3
1.00
1.15
1.0
1.6
1.15
135
1400000
SPF #1
875
Sistering
2x6
1.66
Fully Staggered
12.43
2.486
7.6
20.8
1.5
5.5
2x6
24
4
Rafter
13
2.75
Shingle
30
Roof 1
Date :8/25/2020
Job Code: SALUS RESIDENCE
3 of 6
Load Calculation:
Panels Dead Load (psf) =
Roofing Weight (psf) =
Decking Weight (psf) =
Framing Weight (psf) =
Misc. Additional Weight (psf) =
Existing Dead Load (psf) =
Total Dead Load (psf) =
Ground Snow Load, pg (psf) =
Min Flat Snow, pf_min (psf) =
Min Sloped Snow, ps_min (psf) =
Snow Importance Factor, Ic =
Exposure Factor, Ce =
Thermal Factor, Ct =
Flat Roof Snow, pf (psf) =
Slope Factore, Cs =
Sloped Roof Snow, ps (psf) =
Ultimate Wind Speed (mph) =
Directionality Factor, kd =
Topographic Factor, kzt =
Velocity Press Exp Factor, kz =
Solar Equalization Factor, γa =
External Pressure Up, GCp_1 =
External Pressure Up, GCp_2 =
External Pressure Up, GCp_3 =
External Pressure Down, GCp =
Design Pressure Up, p_1 (psf) =
Design Pressure Up, p_2 (psf) =
Design Pressure Up, p_3 (psf) =
Design Pressure Down, p (psf) =17.7
-24.0
-24.0
0.85
-19.8
-1.15
-1.15
1.00
-0.95
0.70
117
0.85
1.0
Roof 1
30
Wind Load Calculations:
30.24
1.00
Roof 1
1.2
Snow Load Calculations:
40
30
NA
1.0
0.9
7.9
10.9
1.9
1.0
3.0
2.0
Dead Load Calculations:
3.0
Roof 1
Date :8/25/2020
Job Code: SALUS RESIDENCE
4 of 6
Hardware Checks:
Ref. Widthrawal Value, W (lb/in) =
(CM = Ct = Ceg = 1.0) CD =
Adjusted Widthrawal Value, W' (lb/in) =
Lag Penetration, p (in.) =
Allowable Widthrawal Force, W'p (lbs) =
Applied Uplift Force (lbs) =
Uplift DCR =
Ref. Lateral Value, Z (lbs) =
(CM = Ct = CΔ = Ceg = 1.0) CD =
Adjusted Lateral Value, Z' (lbs) =
Applied Laeral Force (lbs) =
Angle of Resultant Force, α (deg) =
Adjusted Interaction Lateral Value, Z'α (lbs) =
Lateral DCR =
Roof Framing Checks:
LC1: D+S
Applied Moment (lb-ft) =
Applied Shear (lbs) =
Allowable Moment (lb-ft) =
Allowable Shear (lbs) =
Moment DCR =
Shear DCR =
LC2: D+0.6W
Applied Moment (lb-ft) =
Applied Shear (lbs) =
Allowable Moment (lb-ft) =
Allowable Shear (lbs) =
Moment DCR =
Shear DCR =
LC3: D+0.75(S+0.6W)
Applied Moment (lb-ft) =
Applied Shear (lbs) =
Allowable Moment (lb-ft) =3034
1605
517
0.27
0.23
3034
1188
832
268
0.73
0.60
2181
854
511
Force Checks:
Roof 1
1589
351
0.52
183
32
1.15
288
0.14
250
820
-114
328
2.5
205
1.6
Lag Screw Checks:
Roof 1
Date :8/25/2020
Job Code: SALUS RESIDENCE
5 of 6
Allowable Shear (lbs) =
Moment DCR =
Shear DCR =
LC4: 0.6D+0.6W
Applied Moment (lb-ft) =
Applied Shear (lbs) =
Allowable Moment (lb-ft) =
Allowable Shear (lbs) =
Moment DCR =
Shear DCR =
LC1: D+L
Deflection (in.) =
Deflection Limit (in.) =
Deflection DCR =
LC2: S
Deflection (in.) =
Deflection Limit (in.) =
Deflection DCR =
LC3: W (Down)
Deflection (in.) =
Deflection Limit (in.) =
Deflection DCR =
LC4: W (Up)
Deflection (in.) =
Deflection Limit (in.) =
Deflection DCR =
Seismic Check:
Wall Weight (psf) =
Tributary Wall Area (ft2) =
Total Wall Weight (lbs) =
Roof Weight (psf) =
Roof Area (ft2) =
Total Roof Weight (lbs) =
Total Existing Weight (lbs) =
1000
17000
8
2400
18938
35938
0.08
Existing Weight:
17
-0.15
1.91
1.91
0.07
0.29
0.14
0.56
1.91
2.8589
0.11
Deflection Checks (Service Level):
Roof 1
0.30
0.07
0.06
3034
1188
207
67
0.53
0.43
1188
Date :8/25/2020
Job Code: SALUS RESIDENCE
6 of 6
PV Panel Weight (lbs) =
Number of Panels =
Total Additional PV Weight (lbs) =
(Existing W + Additional W)/(Existing W) =104%
The increase in weight as a result of the solar system is less than 10% of the existing structure and
therefore no further seismic analysis is required.
Limits of Scope of Work and Liability:
Existing structure is assumed to have been designed and constructed following appropriate codes at
time of erection, and assumed to have appropriate permits. The calculations produced are only for the
roof framing supporting the proposed PV installation referenced in the stamped planset and were
completed according to generally recognized structural analysis standards and procedures, professional
engineering and design experience, opinions and judgements. Existing deficiencies which are unknown or
were not observable during time of inspection are not included in this scope of work. All PV modules,
racking, and mounting equipment shall be designed and installed per manufacturer's approved
installation specifications. The Engineer of Record and the engineering consulting firm assume no
responsibility for misuse or improper installation. This analysis is not stamped for water leakage.
Framing was determined based on information in provided plans and/or photos, along with engineering
judgement. Prior to commencement of work, the contractor shall verify the framing sizes, spacings, and
spans noted in the stamped plans, calculations, and cert letter (where applicable) and notify the
Engineer of Record of any discrepancies prior to starting construction. Contractor shall also verify that
there is no damaged framing that was not addressed in stamped plans, calculations, and cert letter
(where applicable) and notify the Engineer of Record of any concerns prior to starting construction.
Additional PV Weight:
54
25
1361
Weight Increase: