HomeMy WebLinkAboutENGINEERING LETTER - GODWIN ENGINEERINGGODWIN ENGINEERING AND DESIGN, LLC
8378 Foxtail Loop, Pensacola, FL 32526 1 (850)712-4219 1 chad@godwineng.com
September 18, 2019
RECEIVC
To: St. Lucie County Building Division
2300 Virginia Avenue SEP 2 0 2019
Ft. Pierce, FL 34982
ST. Lucie County, Permitting
Re: Peterson - Residential PV Roof Mount Installation �I;ANNE®
5112 Silver Oak Drive
Fort Pierce, FL 34982 BY
I;t I Ilrip rnnnhi
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.'h" 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
Ironridge 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 m }h,�� y Uhave any questions.,\\\, iAIF-I C. ,G'////
g LO G�UfJTY 0 O /�
PLAN REVIEW \I d%•'�VICEpS�QV"
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BLDG:
Sincerely, DAT,Ej�`�� j
D. Chad Godwin, PE 81360 ELE ®te
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Exp.02/28/2021 DATE 'L31°1 �ici.'�_ DRIDP; `��ti���
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DATE;
BUILDING DESIGN PROPERTIES
BASIC WIND SPEED
ROOF PITCH
MEAN ROOF HEIGHT
ROOFSETBACK
HEIGHT AND EXPOSURE
TOPIGRAPHICAL FACTOR
EXPOSURE
EFFECTIVE WIND AREA
UNIT
mph Figure 26.5-IC, page 249a
degrees
ft
It
If
Figure 30.5-1, pg 347
Figure 26.8-1, pg 252
ZONE1
ZONE2
ZONE
VARIABLEDESCRIPTION
SYMBOL
VALUE
VALUE
VALUE UNIT
REFERENCE: ASCE 7.10
NET DESIGN WIND PRESSURE (UPLIFT)
P„„n
-02.1 73.4 -108.5 psf
Figure 305-1, pg 346
NET DESIGN WIND PRESSURE (DOWN)
P.20.3
20.3
20.3 psf
Figure 30.5.1, Pg 346
NET DESIGN WIND PRESSURE(UP)
P�w
-50.94
-88.81
-13129 psf
Calculation: P"iur la Kna P.,a
NET DESIGN WIND PRESSURE (DOWN)
P-m
24.56
24.56
29.56 psf
Calculation: P„,,aa.n=A. Kna P,,a
DESCRIPTION
DEAD LOAD
SNOW LOAD
DESIGN WIND LOAD
ASD DESIGN LOAD (UPUFT)
DOWNFORCE ME I
DOWNFORCECASEZ
DOWNFORCECASE3
SYMBOL VALUE VALUE VALUE
D
5
W
Paam
Pa.um
Pd-a
P�
m30-131.29-99.37327.5621.42
DESIGN FACTORS & CALCULATIONS FOR THE USE OF L-FOOTTO ROOF TRUSS
DESCRIPTION SYMBOL VALUE VALUE VALUE
MODULEWIDTH
B
TOTAL DESIGN LOAD (UPLIFT)
P
TOTAL DESIGN LOAD(DOWNFORCE)
P
DISTRIBUTED LOAD (UPLIFT)
w
DISTRIBUTEDLOAD(DOWNFORCE)
w
RAIL SPAN BETWEEN ANCHORS POINTS
L
POINT MAD(UPUFT)
R
POINT LOAD(UOWNFORCE)
R
L-FOOT CONNECTED BY LAG SCREW TO
ROOFTRUSS/RATTER
Specific Gravity, Rafter
6
Min. Dia. of Lag Screw, 5/16
D
Pullout Value of
W
4 of Lag screws
Thread Length
Ta
Design Pullout Value per Mount
W,
SAFTEY FACTOR
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
0
.243.61
-436.05
0.00
180.81
180.81
0.00
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
1.63
NDIV/01
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UNIT
Pat
psf
PO
Psf
PO
Pat
PO
UNIT
It
psf
PO
pit
pit
it
Its
Its
Calculation: Pam„= D+SQRT(0.6)W (asd)
Calculation: Pa ,=1.OD+1.05
Calculation: P�=1.OD+1.OW
Calculation: Pa ,= I.OD+O.75S+0.75W
Calrula0on: w= PB/2 ea"°'°""mm
Calculation: w=PB/2." -2 me m,w
Calmlation,R=PLB/2•'''"' "'-
Caleubtiom R=PLB/2• "'" 2"a" -
Table 11.2A, NOS 2005, page 68 (Southern Pine)
n
bafn W=1800G�Dya
n Table L2, NOS 2005
W, = W • R of Lags •Ta
Calculation: SF=WyR (Uplift)