HomeMy WebLinkAboutLA185441 -16627 Galaxie Way·
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NORTH
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CAUTION:
BOTH TOP AND LOWER SOCKET JAWS MAY BE ENERGIZED
BY SOURCE AND CUSTOMER SOLAR PV SYSTEM
AC
DISCONNECT
(IF USED)
TO ARRAY
INVERTERPV PRODUCTION
METER (IF
USED)
MAIN SERVICE
PANEL
SUB-PANEL
(IF USED)
(IF NO
SUB-PANEL)
CABLE TRAY (IF USED)
TRUE
NORTH
PERMITTING SECTION
BUILDING COST (CONSTRUCTION COST X 0.2)=$1,206
ELECTRICAL COST (CONSTRUCTION COST X 0.8)=$4,826
CONSTRUCTION COST (SYSTEM SIZE X 1.45)=$6,032
UTILITY SERVICE SIZE (IN AMPS)=100A
TOTALS AMPS ADDED TO UTILTY=
16A (IF MULITIPLE
INVERTERS MULTIPLY THIS BY
HOW MANY INVERTERS ARE
BEING USED)
ROOF SQ FOOTAGE =1972
PANEL SQ FOOTAGE =236
55 WEST 500 SOUTH, HEBER CITY, UT 84032
T 925.787.3067 U RIGHTANGLEENG.COM
September 15, 2020
Total Solar Solutions
34778 N. 300 W. Ste. 150
Provo, UT 84604
RE: Structural Roof Evaluation for the Dawn Residence: 16627 Galaxie Way,
Rosemount, Minnesota
As per your request, we have evaluated the roof structure under the proposed solar panel array. The
information used to evaluate this structure was gathered during a field visit by Total Solar Solutions on
behalf of Right Angle Engineering. The roof structure consists of pre-manufactured trusses spaced at 24”
on center. The roof material consists of asphalt shingles. The design criteria used to analyze this
structure are listed above and included with this letter. The adopted building codes in this jurisdiction
are: the 2018 International Building Code, the 2018 International Existing Building Code, and ASCE 7-16.
International Existing Building Code (IEBC) 2018 section 806.2 indicates that alterations to an existing
building that results in less than a 5% increase in the total stress may be performed without a structural
evaluation of the existing building. As demonstrated in the attached calculations, the additional weight
of the solar panels will be less than 5% increase in the gravity loading and the stress on the existing roof
framing.
Based on our assessment we have determined that the existing roof framing will safely and adequately
support the additional loads imposed by the solar panels. In order for the loads to be evenly distributed,
the roof attachments should be staggered and spread evenly throughout the panel array. Attachment
points should be spaced at a maximum of 48” on center. The racking system should be installed per the
manufacture’s specifications. There should be a minimum of 22 L-foot attachment points to the roof.
Each attachment should have a 5/16” or 18/8 SS lag screw with 2.5” minimum penetration centered on
each truss top chord. Waterproofing around the roof penetrations is the responsibility of others. Right
Angle Engineering assumes no responsibility for improper installation of the solar panels.
Regards,
Robert D Smythe, P.E.
Right Angle Engineering
9/15/20
Design Criteria:
Ultimate Wind Speed- 115 mph
Ground Snow Load- 50 psf
Risk Category- II
Exposure category- C
2
Design Criteria:
Design Wind Speed (3 second gust) 115 mph
Exposure Category C
Risk Category 2
Mean Roof Height 30 ft
Roof Type Gable Roof
Building Type enclosed
Roof Dead Load- ASCE Table C3-1
Asphalt Shingles 2 psf
5/8" Plywood Sheathing 2 psf
Roof Framing 4 psf
Insulation 3.85 psf
Gypsum sheathing 2 psf
Solar Panel Array 3 psf
Dead Load Without Panels 13.85 psf
Dead Load With Solar panels 16.85 psf
Roof Live Load
Existing Roof Live Load 20 psf ASCE 7-16 Table 4.3-1
Roof Live Load with Solar Panels 0 psf 2018 IBC 1607.13.5.1
Roof Snow Load-ASCE 7-16
Ground Snow Load (pg) 50 psf Section 7.2
Exposure Factor (Ce) 0.9 Table 7.3-1
Thermal Factor (Ct) 1.1 Table 7.3-2
Importance Factor (Is) 1 Table 1.5-2
Flat Roof Snow Load (Pf) 35 Equation 7.3-1
Slippery surface Slope Factor (Cs) 0.85 Figure 7-2
Nonslippery Surface Slope Factor
(Cs) 1 Figure 7-2
Roof Snow Load 35 psf Equation 7.4-1
Reduced Roof Snow Load (Slippery
Surface) 29 psf Equation 7.4-1
Load Combinations - ASCE 7-16 Section 2.4.1
Without Solar Panels
With Solar
panels
D + Lr 33.8 psf 16.8 psf
D + S 48.5 psf 46.3 psf
3
Solar Array 1-
Roof Slope 19 degrees
Number of panels 13
Panel Area 227.5 ft^2
Wind Calculations- ASCE 7-16
GCp Zone 1 -0.9 Figure 30.3-(2A-5B)
GCp Zone 2 -1.7 Figure 30.3-(2A-5B)
GCp Zone 3 -2.6 Figure 30.3-(2A-5B)
Gcpi 0.18 Table 26.13-1
Velocity Pressure (qh) 28.2 psf
qh= .00256KhKhtKdV^2 Equation 26.10-1
Kh 0.98 Table 26.10-1
Kht 1 Equation 26.8-1
Kd 0.85 Table 26.6-1
Designed wind pressure (P) psf Equation 30.8-1
P= qh(GCh) - (GChi))
Zone 1 Pressure (P) -30.5 psf
Zone 2 Pressure (P) -53 psf
Zone 3 Pressure (P) -78.4 psf
Roof Connection
Shear Capacity 190 lbs NDS 2015 Table 12K
Shear tributary area 18 ft^2
Pullout Capacity 266 lbs/in
Lag screw embedment 2.5 in
Total pullout capacity 665 lbs NDS 2015 Table 12.2A
Pullout max tributary area 12.5 ft^2
Factor of Safety 1.41
Minimum number of connections 22
Beam Stress IEBC 2018 Section 806.2
Beam Span 14 ft
Spacing 2 ft
Roof Framing type pre-manufactured trusses
Panel Orientation portrait
Number of Panels per rafter 2
Panel distance from eave 0
Without Solar
Panels
With Solar
Panels
Percent
Increase
Bending Moment 2376.5 ft-lbs 1138.5 ft-lbs 47.9% Less than 105%
Vertical Reaction (V1) 679 lbs 701.9 lbs 103.4% Less than 105%
Vertical Reaction (V2) 679 lbs 562.6 lbs 82.9% Less than 105%