Stamped PE Calcs - Daniels, MarcFreedom Forever LLC
43445 Business Park Dr Suite 110
Temecula, CA 92590
Attn.: To Whom It May Concern
re job:Daniels, Marc
20 VALLEY ST,
NORTHAMPTON, MA 01060
Design Criteria:
Code:2015 IBC w/ 780 CMR
ASCE 7-10
Live Load:20 psf
Ult Wind Speed:120 mph
Exposure Cat:B
Ground Snow:40 psf Min Roof Snow:35
Current Renewables Engineering Inc.
Professional Engineer
info@currentrenewableseng.com
11/17/2020
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.
Date :11/17/2020
Job Code: Daniels, Marc
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) =543
1019
756
155
1418
1996
216
1.15
2777
1.5
1.00
1.15
1.0
1.6
1.15
135
1400000
SPF #1
875
Sistering
2x4
1.33
Fully Staggered
10
2
3.1
5.4
1.5
3.5
2x4
24
4
Rafter
23
1.65
Shingle
33
Roof 1
Date :11/17/2020
Job Code: Daniels, Marc
3 of 6
E' (psi) =
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 =
Velocity Pressure, qz (psf) =
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) =18.7
-25.2
-25.2
0.85
-20.9
-1.15
-1.15
-0.95
0.70
22.0
120
0.85
1.0
Roof 1
24
Wind Load Calculations:
35
0.67
Roof 1
1.2
Snow Load Calculations:
40
35
NA
1.0
0.9
7.2
10.2
1.2
1.0
3.0
2.0
Dead Load Calculations:
3.0
Roof 1
1400000
Date :11/17/2020
Job Code: Daniels, Marc
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) =
906
362
0.38
0.28
1418
756
535
214
0.83
0.62
1019
543
337
Force Checks:
Roof 1
843
378
0.25
95
37
1.15
288
0.09
250
820
-73
328
2.5
205
1.6
Lag Screw Checks:
Roof 1
Date :11/17/2020
Job Code: Daniels, Marc
5 of 6
Allowable Moment (lb-ft) =
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) =
3000
51000
7
2400
17288
68288
0.17
Existing Weight:
17
-0.26
1.53
1.53
0.15
0.46
0.24
0.71
1.53
2.3
0.20
Deflection Checks (Service Level):
Roof 1
0.46
0.11
0.08
1418
756
160
64
0.64
0.48
1418
756
Date :11/17/2020
Job Code: Daniels, Marc
6 of 6
PV Panel Weight (lbs) =
Number of Panels =
Total Additional PV Weight (lbs) =
(Existing W + Additional W)/(Existing W) =101%
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
16
871
Weight Increase: