The Community Builder with Solar Map, NorthamptonTo:Sunbug Solar
411A Highland Ave
Somerville, MA 02144
Subject:Structural Certification for Installation of Solar Panels
The Community Builders
35 Village Hill Road
Northampton, MA. 01060
To Whom It May Concern,
Design Criteria:
●Applicable Codes = Massachusetts Building Code, 9th Edition, ASCE 7-12, and 2015 NDS
●Roof Dead Load = 9.73 psf (MP1)
●Roof Live Load = 20 psf
●Wind Speed = 117 mph, Exposure B
●
Sincerely,
Elaine Huang, P.E.
Project Engineer
I further certify that all applicable loads required by the codes and design criteria listed below were applied to the
Ecolibrium solar ballast 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 Ecolibrium for the solar ballast
system. Finally, I accept the certifications indicated by the solar panel manufacturer for the ability of the panels to
withstand high wind and snow loads.
October 5, 2020
A design check for the subject complex 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 TPO over rigid insulation that is supported by 5/8 plywood sheathing. The
plywood sheathing is supported by pre-fabricated 20" deep trusses at 24" o.c., spanning in transverse direction. The
trusses have various span and are simply supported by load bearing walls. The width of the building is divided into two
bays of trusses. The truss members are connected by steel gusset plates.
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 capacity of the roof trusses are marked on the drawings
attached with this report, from 8 psf to 20 psf, depending on the location of the area on the roof
Ground Snow Load = 50 psf - Roof Snow Load = 35 psf
Please contact me with any further questions or concerns regarding this project.
The Community Builder, Northampton 1
50 psf
(ASCE7 - Eq 7-1)
1 (ASCE7 - Table 7-2)
1 (ASCE7 - Table 7-3)
1
35.0 psf
(ASCE7 - Eq 7-2)
1
35.0 psf
2.00
2.00
0.73
0.00 (Ceiling Not Vaulted)5.009.7 psf
9.7 psf
Gravity Loading
PV Dead Load = 8 psf (Per Sunbug Solar)
2x4 Top Chords @ 24"o.c.
Total Roof DL (MP1)
DL Adjusted to 2 Degree Slope
Roof Snow Load Calculations
pg = Ground Snow Load =
Miscellaneous
Roof Plywood
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)
TPO
ps = Cspf
ps = Sloped Roof Snow Load =
pf = Flat Roof Snow Load =
The Community Builder, Northampton 2
Per ASCE 7-12 Components and Cladding
117 mph
BGable/Hip2 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 =-0.98 -1.63 -2.38 0.28 (Fig. 6-11)
Uplift Pressure =-20.33 psf -33.88 psf -49.52 psf 10.0 psf (Minimum)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 =-224 lb -373 lb -545 lb
Wind Calulations
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
Input VariablesWind Speed
Effective Wind Area
Design Wind Pressure Calculations
Roof Shape
Building Least Width
Roof Slope
The Community Builder, Northampton 3
PASS
Dead Load 9.7 psfPV Load 8.0 psf
Snow Load 35.0 psf
Governing Load Combo = DL + SLTotal Load 52.7 psf
Fb (psi) =f'b x Cd x Cf x Cr (NDS Table 4.3.1)875 x 1.15 x 1.5 x 1.15
Allowed Bending Stress = 1735.7 psi
(wL^2) / 8
=398.815 ft#
=4785.79 in#
Actual Bending Stress = (Maximum Moment) / S
= 1562.8 psi
L/180 (E = 1400000 psi Per NDS)=0.366 in
Deflection Criteria Based on =(5*w*L^4) / (384*E*I)=
=L/228 <L/180 Therefore OK
Allowed Deflection (Live Load) =L/240
0.275 in(5*w*L^4) / (384*E*I)
L/342 <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 =290 lb
Framing Check (MP1)
Simple Span
0.290 in
0.193 in
Member Properties
Member Size2x4 S (in^3)3.06 SPF#2 Member Spacing@ 24"o.c.
Maximum Moment =
Check Deflection
I (in^4)5.36 Lumber Sp/Gr
Actual Deflection (Live Load) =
Allowed Deflection (Total Load) =
Actual Deflection (Total Load) =
Allowed > Actual -- 90.1% Stressed -- Therefore, OK
473 lb
Allowed > Actual -- 61.4% Stressed -- Therefore, OK
5.3 in^2
Check Shear
w = 105 plf
(True Dimensions)
Check Bending Stress
2x4 Top Chords @ 24"o.c.
Member Span = 5' - 6"
The Community Builder, Northampton 4
ProductsPlotID Length Product Plies Net QtyJ1-24" O.C. 10' 0" 9 1/2" PJI-60 1 17B1-1 20' 0" 1.75" x 9.5" 2.0E PWLVL 1 2B2-1 24' 0" 1.75" x 20" 2.0E PWLVL 2 2B3-1 28' 0" 1.75" x 20" 2.0E PWLVL 1 1B3-1 14' 0" 1.75" x 20" 2.0E PWLVL11B4-1 14' 0" 1.75" x 20" 2.0E PWLVL 1 1FB1-2 6' 0" 1.75" x 20" 2.0E PWLVL 2 4Truss Connector Total ListManuf Product QtyMSH422 6THF25925 16RT7A 220RTU-1761 LBS10d x 3fastenersDimension from inside faceof wall to C\L of trussDimension from inside faceof wall to C\L of trussDimension from inside faceof wall to C\L of trussDimension from inside faceof wall to C\L of trussAdditional load added for HP units.Not shown on layout aboveThese joists to be hung with THF25925 from 2x10ribbon attached to floor trusses per detail 29 pageS306Location of point load of65lbs DL and 60lbs Snowfrom parapet diagonalThis truss has a uniforn load of 40lbs DLand 45lbs Snow from parapet diagonalDO NOT INSTALL WRONG TRUSS IS(1) RT7A at each roof trussto wall connectionBBO in wallBBO in wallBBO in wallB2-1B3-1B4-1FB1-2FB1-2--B1-1B1-1J1-24" O.C.J1-24" O.C.J1-24" O.C.J1-24" O.C.J1-24" O.C.J1-24" O.C.J1-24" O.C.J1-24" O.C.J1-24" O.C.J1-24" O.C.J1-24" O.C.J1-24" O.C.J1-24" O.C.J1-24" O.C.J1-24" O.C.J1-24" O.C.J1-24" O.C.T05T09T09T13T13T13T13T13T13GRT13T05AT05BT05AT05BMSH422MSH422MSH422MSH422T03(14)T03(7)T04(8)T06(6)T07(6)T08(8)T09(3)T10(12)T10(11)T11(8)T12(5)T02(10)26' 9 1/2"22' 11 1/4"2' 0" 2' 0" 22' 8 3/4"4' 0" 2' 0" 23' 11 1/4"21' 9 1/2"17' 4 3/4"9' 7 1/4" 16' 10 1/4"50' 2 1/4"2' 0"24' 10 1/4"13' 4" 3' 8" 2' 0" 2' 0" 37' 0"8' 8"24' 4"3' 11 1/4"2' 4 3/4"13' 11 1/2"19' 3 1/4"3' 9 3/4"1' 11 1/2"2' 0" 2' 0" 2' 0" 2' 0" 2' 0" 2' 0" 2' 0" 2' 0" 2' 0" 2' 0" 2' 0" 2' 0" 2' 0" 2' 0" 2' 0" 2' 0" 2' 0" 2' 0" 2' 0" 2' 0" 2' 0" 2' 0" 2' 0" 2' 0" 2' 0" 2' 0" 2' 0" 2' 0" 2' 0" 2' 0" 2' 0" 2' 0" 2' 0" 2' 0" 2' 0" 2' 0" 2' 0" 2' 0" 2' 0"1' 10 1/4"2' 1 3/4"2' 0"2' 1 1/4"2' 0"2' 0"2' 0"2' 0"2' 0"2' 0"2' 0"2' 0"2' 0"2' 0"2' 0"2' 3" 2' 0" 2' 0" 2' 0" 2' 0" 2' 0" 2' 0" 2' 0" 2' 0" 2' 0" 2' 0" 2' 0" 2' 0" 2' 0" 2' 0" 2' 0" 2' 0" 2' 0" 2' 0" 2' 0" 2' 0" 2' 0"1' 8 1/2"1' 8 1/2"2' 0" 2' 0" 2' 0" 2' 0" 2' 0" 2' 0" 2' 0" 2' 0" 2' 0" 2' 0" 2' 0" 2' 0" 2' 0" 2' 0" 2' 0" 2' 0" 2' 0" 2' 0" 2' 0" 2' 0" 2' 0"1' 11 1/2"2' 2" 2' 0" 2' 0" 2' 0" 2' 0" 2' 0" 2' 0" 2' 0" 2' 0" 2' 0" 2' 0" 2' 0"1' 11 1/4"1' 9 1/2"1' 6"1' 7 3/4"4' 7 1/2"5' 0 1/4"120' 2 1/4"122' 2 1/4"Roof Area 4983.58 ft²Sheathing Count* 171 sheetsOverhang Lines 340.88 ftRaked Lines 0 ftRidge Lines 0 ftHip Lines 0 ftValley Lines 0 ftTHIS IS A TRUSS PLACEMENT DIAGRAM ONLY. These trusses are designed as individual building components to beincorporated into the building design at the specificationof the building designer. See individual design sheets for eachtruss design identified on the placement drawing. The building designer is responsible for temporary and permanent bracingof the roof and floor system and for the overall structure. The design of the truss support structure including headers, beams,walls, and columns is the responsibility of the building designer. For general guidance regarding bracing, consult "Bracing ofwood trusses" available from the Truss Plate Institute, 583D'Onifrio Drive; Madison, WI 53179. It is the responsiblility of theGeneral Contractor/Superintendent to verify that the provided truss layout shall match the final intended construction plans,loading conditions, and use. If they do not, it is the responsiblility of the General Contractor/Superintendent to provideprints/plans containing the latest specifications and designs. Universal Forest Products will not be responsible forprint/planchanges by others after final approval ofshop drawings, norwill they be responsible for errors or modifications made on-siteduring construction. DO NOT CUT, NOTCH, DRILL, OR OTHERWISE"REPAIR" MANUFACTURED TRUSSES IN ANY WAYWITHOUT PRIOR WRITTEN AUTHORIZATION BY A LICENSED PROFESSIONAL DESIGNATED BY UFP. UFP WILL NOTBE HELD RESPONSIBLE FOR ANY MODIFICATIONS OR "CHARGE BACKS"DONE WITHOUT PRIOR WRITTENAUTHORIZATION FROM UFP35 Village Hill RdNorthampton, MA3/2/2020 By: TJRFor ApprovalRoof FramingThe following information is anapproximate and NOT guaranteed*Sheating count is an approximateand NOT guaranteedPO Box 945 / 155 Bay RoadBelchertown, MA 01007PH: 413-323-7247FX: 413-323-5780Left End ofTruss SymbolLeft End of Truss SymbolF09*Note; To be used with truss drawings / Wood trussdoes not have symbol on it.Left End of Truss Symbol