HomeMy WebLinkAboutMISC. LETTERGODWIN ENGINEERING AND DESIGN, LLC
8378 Foxtail Loop, Pensacola, FL 32526 1 (850)712-4219 1 chadpgodwinengcom
September 16, 2019
SCANNED
To: St. Lucie County Building Division BY
2300 Virginia Avenue St. Lucie County
Ft. Pierce, FL 34982
Re: Otero - Residential PV Roof Mount Installation
109 SE Solaz Ave , oll
Port St. Lucie, FL 34983 !�
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.
The existing roof covering is Asphalt Shingle with min.1h" 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 asphalt shingle roof with the
Quickmount Q-rail Light railing and flashings/attachments. The attachments 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 a min. 5/16" lag screw with minimum 2-
5/16" thread length.
Please see attached documents and contact me should you have any questions. 111
Sincerely,
D. Chad Godwin, PE 81360
Exp.02/28/2021
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BUILDING DESIGN PROPERTIES
SYMBOL
VALUE
UNIT
BASICWINDSPEED
y
160
mph
Figure 26.5-IC, page 249a
ROOF PITCH
B
>7ro27
degrees
MEAN ROOF HEIGHT
h
I51"'
k
ROOF SETBACK
a
�- -3
ft
ADJUSTMENT FACTOR FOR BUILDING
HEIGHT AND EXPOSURE
X
1.21
Figure 3D.5-1, pg 347
TOPIGRAPHICALFACIOR
K
- 1
Figure 26.8-1. pg 252
EXPOSURE
EFFECTIVE WIND AREA
sf
ZONE1
ZONEZ
ZONE3
VARIABLE DESCRIPTION
SYMBOL
VALUE
VALUE
VALUE UNIT
REFERENCE: ASCE 7-10
N ET DESIGN WIND PRESSURE(UPLI 9)
P,,,,y
42.1
-73.4
-108.5
psf
Figure 30.5-1, pg 346
N ET DESIGN WIND PRESSURE(DOWNI
PM,w
20.3
20.3
20.3
psf
Figure 3D.5-1, pg 346
NET DESIGN WIND PRESSURE (UP)
P"nw
-50.94
88.81
-131.29
psf
Calmlation:P°,w°=Xx Kaxp"[,m
NET DESIGN WIND PRESSURE (DOWN)
Pre, do,.a
24,56
24.56
24.56psf
Calculation: P,,,, a_ Xx Knx P_nd
DESCRIPTION
DEAD LOAD
SNOW LOAD
DEIGN WIND LOAD
ASD DESIGN LOAD (UPLIFT)
DOWNFORCE CASE 1
DOWNFORCE CASE 2
DOWNFORCE CASE 3
DESCRIPTION
MODULE WIDTH
TOTAL DESIGN LOAD (UPLIFT)
TOTAL DESIGN LOAD (DOWNFORCE)
DISTRIBUTED LOAD (UPLIFT)
DISTRIBUTED LOAD (DOWNFORCE)
RAIL SPAN BETWEEN ANCHORS POINTS
POINT LOAD (UPUFT)
POINTLOAD(DOWNFORCE)
L-FOOT CONNECTED BY LAG SCREW TO
ROOF TRUSS/RAFTER
Specific Gravity, Rafter
Min. Dia. of Lag Screw, 5/16
Pullout Value of
# of Lag screws
Thread Length
Design Pullout Value per Mount
SAFTEY FACTOR
SYMBOL VALUE VALUE VALUE
D
5
W
Pam,
Pam,
Pdm,
Pd.,
3
0
31.29
&27.56
.99.37
3
27.5621.42
SYMBOL VALUE VALUE VALUE
B
P
P
w
L
R
R
G
D
W
Td
W,
SF
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
180.82
90.41
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
709.639
2.91
1.63
2.18
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wn Iwrmam_a d.a..r..,a®.r
ppmtl,YMx�lMmr PU>aablm�HLer
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aYt Real N
i >!
G.6x. Ba.a(.z TF
Fw ar¢ao raa��wa-rrh Ww.da. a....a._ � aai.
UNIT
psf
PSI
psf
psf
Pat
psf
Pat
UNIT
ft
Psf
psf
PR
plf
R
Ibs
Ibs
Calculation: Pd,s„=D+SORT(0.6)W (asd)
Calculation: Pdms•=1.OD+I.OS
Calculation: Pd..le�=1.OD+1.OW
Calculation: P&,,= 1.00+0.75S+OJ5W
Calalation: W=PB/2
Calculation,w=•°` inepi1kpe10W
Calculation: R = PUB/2 •u`"'""""a°"'�"
Calculation: R = PUB/2'^`mmax
Table 11.2A, ND52005, page Be (Southern Pine)
n
bs/in W=180DG'n DVs
n Table L2, NOS 2005
W,= W • # of Lags •Td
Calculation: SF=WyR (Uplift)
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