HomeMy WebLinkAboutLetterGODWIN ENGINEERING AND DESIGN, LLC
8378 Foxtail Loop, Pensacola, FL 32526 1 (850)712-4219 1 chad(@godwineng.com
RFC
January 3, 2020Fo
BAN
a �81070
To: St. Lucie County Building Division e"St ngoepdq
2300 Virginia Avenue Co jn��' e
Ft. Pierce, FL 34982
Re: Indarjit - Residential PV Roof Mount Installation
613 Beach Ave.
Port St. Lucie, FL 34952
FILE Copy
Plan Reviewer,
This letter is regarding the installation of a new roof mounted Solar PV System on the existing
residential structure at the address above. I have reviewed the attachment plan and have
determined that the roof mounted PV system is in compliance with the applicable sections of the
following Codes as amended and adopted by the jurisdiction:
2017 Florida Building Code 6th Edition, FBC
ASCE 7 Min. Design Loads for Buildings & Other Structures
Per 2017 FBC, the Roof Mounted PV system will be subject to the following design criteria: Design
Wind Speed(V it) - 160mph 3sec gust, Exposure Category - C
The PV System consist of the modules, railing, and connection hardware. The system will add a
dead load of approximately 3 psf to the roof.
There are two existing roof coverings; one is shingle with min. 1/2" plywood decking and 2" x 4" roof
trusses 24" O.C. The other is flat roof with modified bit over min. 1/2" plywood decking and 2" x 4"
roof trusses 24" O.C. The roofing, decking, and roof trusses are in good condition. The existing
structure will be adequate for supporting the additional PV dead load and wind loads.
The securement method of the PV system is to be flush mounted to the roofs with the Ironridge
railing and flashings/attachments. The attachments for the shingle roof can be attached up to 48"
apart and should be staggered, where possible, to allow distribution of the design loads evenly to
the structure. The mounts shall be installed with a min. 5/16" lag screw with minimum 2-5/16"
thread length directly to roof truss. The mounts for the modified bit roof are the RT mini and can be
attached up to 48" apart. The mounts should be staggered, where possible, to allow distribution of
the design loads evenly to the structure. The mounts shall be installed with 2 x MS x 60 \\�11111/////
stainless lag screws directly to the roof truss. `\\\\Oxx. C ENS OO�///
Please see attached documents and contact me should you have any questions. * 13 0
Sincerely, �O' TA pF ' Q/�`
D. Chad Godwin, PE 81360 �/ 3'4 loP" ��\
Exp. 02/28/2021 �NAL
///1111101/3/�i
UNIT
psf
psf
psf
psi
Calculation: Pdwalc D+SQRT(0.6)W (asd)
psf
Calculation: Pyg 2.0D+1.OS
psf
Calculation: Pa ,=I.OD+I.OW
psf
Calculation: Pd ,, I.OD+DJSS+OJSW
UNIT
ft
psf
Psf
plf
Calculation: w=PB/2 •"iunizi11yp"'""
pH
Calculation: W=PB/1.1i"°"SNh,
ft
Ibs
Calcula0om R=PCB/2 •Piuna ziLLpe10'
Ibs
Calcuation: R=PUB/2.1,-z,.ft,-
Table 11.2A, Nos 2005, page 68 (Southern Pine)
n
bs/in W=18DOG3ADzl4
n Table L2, NOS 2005
W, - W • # of Lags •Td
Ci loulatlon: SF=WyR (Uplift)
BUILDING DESIGN PROPERTIES
BASIC WIND SPEED
ROOF PITCH
MEAN ROOF HEIGHT
ROOFSETBACK
ADJUSTMENT FACTOR FOR BUILDING
HEIGHTAND EXPOSURE
TOPIGRAPHICAL FACTOR
EXPOSURE
EFFECTIVE WIND AREA
UNIT
mph Figure 26.5-1C, page 249a
degrees
It
R
0
Figure 30.5-1, pg 347
Figure 26.8-1, pg 252
ZONE1
ZONE2
ZONES
VARIABLE DESCRIPTION
SYMBOL
VALUE
VALUE
VALUE UNIT
REFERENCE: ASCE 7-1D
NET DESIGN WIND PRESSURE (UPLIFT)
P,„,sa
42.1 73.4 -108.5 POFigure
30.5-1, pg 346
N ET DESIGN WIND PRESSURE (DOWN)
P.,y
1 20.3
20.3
20.3 psf
Figure 30.5-1, pg 346
NET DESIGN WIND PRESSURE (UP)
P,-50.94
418.81
-131.29 psf
CaIwIadon:P„y"a=Ax Knx Pn:,tp
NET DESIGN WIND PRESSURE (DOWN)
Pn.,,-.
1 24.56
24.56
24.56psf
Calculation: P11edm1=AXKex Pnem
DESCRIPTION SYMBOL VALUE VALUE VALUE
DEAD LOAD
D
SNOW LOAD
S
DESIGN WIND LOAD
W
ASD DESIGN LOAD( UPLIFT)
N.',
DOWNFORCE CASED
Pdwn
DOWNFORCECASE2
Pyp
DOWNFORCE CASE
Pdmn
m30131.29-99.37327.5621.42
DESIGN FACTORS At CALCULATIONS FOR THE USE OF L-FOOT TO ROOF TRUSS
DESCRIPTION SYMBOL VALUE VALUE VALUE
MODULEWIDTH
B
TOTAL DESIGN LOAD (UPLIFT)
P
TOTAL DESIGN LOAD (DOWNFORCE)
P
DISTRIBUTED LOAD (UPLIFT)
w
DISTRIBUTED LOAD (DOWNFORCE)
w
RAIL SPAN BETWEEN ANCHORS POINTS
L
POINT LOAD (UPLIFT)
R
POINT LOAD (DOWNFORCE)
R
t-FOOT CONNECTED BY LAG SCREW TO
ROOFTRUSS/RAFTER
3.28
3.28
3.28
.37.13
-66.47
-99.37
27.56
27.56
27.56
-60.90
-109.01
-162.97
45.20
45.20
45.20
4
4
2
.243.61
436.05
.325.93
180.81
180.81
90.41
Specific Gravity, Rafter
6
Min. Dia. of Lag Screw, 5/16
D
Pullout Value of
W
# of lag screws
Thread Length
Td
Design Pullout Value per Mount
WI
SAFTEY FACTOR
SF
ary a� oau..lrv.yaArl...Mvaa
0.55
0.55
0.55
0.3125
0.3125
0.3125
306.87
306.87
306.87
1
1
1
2.3125
2.3125
2.3125
709.64
709.636
709.636
2.91
2.63
2.18
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FYt Roof
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