HomeMy WebLinkAboutENGINEERING LETTER - GODWIN ENGINEERINGTo:
Re:
GODWIN ENGINEERING AND DESIGN, LLC
8378 Foxtail Loop, Pensacola, FL 32526 1 (850)712-4219 1 chad(&godwineng.com
May 16, 2019
SCANNED
St. Lucie County Building Division BY
2300 Virginia Avenue St. Lucie County
Ft. Pierce, FL 34982
Bond - Residential PV Roof Mount Installation
3408 Avenue South FILE CU
Fort Pierce, FL 34947
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. 1 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. %" 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 me should you have any questions.
Sincerely,
D. Chad Godwin, PE 81360
Exp.02/28/2021
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BUILDING DESIGN PROPERTIES
SYMBOL VALUE
UNIT
BASICWINDSPEED
V
16D I'�
mph
Figure 26S.1C, page 249a
ROOF PITCH
B
a) to 27
degrees
MEAN ROOF MIGHT
h
15 F
k
ROOF SETBACK
a
3
k
ADJUSTMENT FACTOR FOR BUILDING
HEIGHTAND EXPOSURE
A
1.21
Figure 30.5-1, pg 347
TOPIGRAPHICALFACTOR
K
1
Figure 26.8-1pg252
EXPOSURE
C
EFFECTIVE WIND AREA
10,:_
of
ZONES
ZONE2
ZONE3
VARIABLE DESCRIPTION
SYMBOL
VALUE
VALUE
VALUE UNIT
REFERENCE:ASCE 7.10
NET DESIGN WIND PRESSURE( UPLIFT(
P_.
42.1
-73.4
-108.5
psf
Figure 30.5-1, pg 346
NET DESIGN WIND PRESSURE (DOWN)
P„,p
20.3
20.3
20.3
psf
Figure 30.5-1, pe 346
NET DESIGN WIND PRESSURE (UP)
P,..o
-50.94
88.81
-131.29
psf
Calculation: P,.,,p A K.x P..y
NET DESIGN WIND PRESSURE (DOWN)
P.. m..
7A.56
24.56
24.56
psf
Calculation: P..m.,,=Ax K.x P,.uo
DESORPTION
DEAD LOAD
SNOW LOAD
DESIGN WIND LOAD
ASO DESIGN LOAD (UPLIFT)
DOWNFORCE CASE I
DOWNFORCE ME
DOWNFORCECASE3
SYMBOL VALUE VALUE VALUE
D
5
W
Pe.b,
Pa.b,
P"
Penh,
m30131.29-9937327.5621.42
DESIGN FACTORS & CALCULATIONS FOR THE USE OF L-FOOT TO ROOFTRU55
DESCRIPTION SYMBOL VALUE VALUE VALUE
MODULEWIDTH
B
TOTAL DESIGN LOAD (UPLIFT)
P
TOTAL DESIGN LOAD (DOWNFORCE)
P
DISTRIBUTED LOAD (UPLIFT)
w
DISTRIBUTED LOAD (DOWNFORCE)
RAIL SPAN BETWEEN ANCHORS POINTS
L
POINT LOAD (UPLIFT)
R
POINT LOAD (DOWNFORCE)
R
L-FOOT CONNECTED BY LAG SCREW TO
ROOF TRUSS/ RAFTER
5peci0c Gravity, Rafter
G
Min. Dia. of lag Screw, 5/16
D
Pullout Value of
W
R of lag screws
Thread Length
T4
Design Pullout Value per Mount
W,
SAFTEY FACTOR
SF
3.28
3.28
3.28
-37.13
-66A7
-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
190.81
180.81
90.41
0.55
0.55
0.55
0.3125
0.3225
0.3125
306.87
306.97
306.87
1
I
1
23125
2.3125
2.3125
709.64
709.636
709.636
2.91
2.63
2.18
3u.LOenwlaa3m73sIr..N.i1
119 ar/l�imnl YGa�44e�r4.nYdr
pMmWN.ak\b a..PymnaYrvrAb�
L 3.rl..dJgOalam3
a.3 eel ea.W .n
FYa Ilmr
Cabre Ree,(4a r)elle
{EI
UNIT
PSI
Psf
Psf
Pat
Pat
Pat
Pat
UNIT
It
psf
psf
pit
pU
k
Ibs
Its
Calculation: Pa = D.SORT(0.6)W(asd)
Calculation: Pay SDD.1.05
Calculation: Pm=1.DD.1.OW
Calmlatlon: Pea m 1.0D.0.755.0.75W
Calculation: w= Pa/2.__I.,-
Cal.L.Uon:w=PB/2.L _u ae.-
Calculation: R=PLB/2'"SY""•".me.�.
Calculation: R = PLB/2 •"n"'"""'"`P"°"
Table 11.2A, NDS 2005, page 6B (Southern Pine)
In
Ibs/in W=1800 GM DW4
In Table 12, ND52005
W,= W • R of Lags •Te
Calculation: SF=WyR(Uplift)
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