HomeMy WebLinkAboutLetterDaniel W. Dunzik
370 Burnt Hill Rd. Skillman NJ. 08558
StudioGdesign@comcast.net
Re: Proposed Photovoltaic Solar Panel Installation
John Poli
405 SE Gasparilla Ave
Port St. Lucie, FL 34983
Dear Plan Reviewer:
Architect LEED-AP
908-872-3664
January 10, 2020
RECEIVED
JAN 15 2020
ST. Lucie County, Permitting
Certification: I have reviewed the engineering testing reports for the racking and attachments to be used on this
project and I certify that the products are capable of supporting the code required loads and are suitable for this
installation when installed in strict compliance with the manufacturers printed instructions.
Regarding the solar panel array installation on the above referenced project please note that an inspection was
performed by a representative of the Architect/Engineer of Record, and analysis of the existing structure was
conducted. There is adequate structural capacity for the installation of the array with the following recommendations:
1. The array will be installed on the existing roof. The roof framing is constructed of 2"x4" wood rafters @24" o.c.
spanning 159" with 1/2" plywood sheathing. The new array (See Site map by contractor) will add 2.63 Lb. / St.
overall to the roof. No additional structural support is required for the roof structure.
2. The system shall be secured to the roof using the "SnapNrack" "Ultra Rail" ® attachment system. The installation
shall be in strict compliance with manufacturers printed instructions. The attachment system shall be UL 1703
approved tested. The attachments shall be min. 5/16" x 4" long stainless -steel lags with a min. embedment of 3" into
the rafters. Attachments shall be @ 48" o.c. Max. in roof wind zone I and @ 24" o.c. Max. in roof wind zone 2 & 3,
lags to alternate rafters. Provide 6 mil. vapor barrier between dissimilar metals. Provide water tight gasket and sealant
at all penetrations. Attachments shall follow panel rows as specified by the system manufacturer's installation
manual. The panel angle shall match the roof slope.
3. Solar Modules shall be UL-1703 rated. Refer to manufacturers specifications sheets.
4. Positive drainage of the system shall be so as not to void the existing roof warranty.
5. All aspects of the installation shall comply with the Florida Administrative Code, 2017 Florida Building Code -
Residential Sixth Edition, ASCE-7-10, 2017 Florida Building Code — Energy Conservation, Sixth Edition, 2014
National Electric Code, All Local Governing County and Municipal Ordinances adopted by reference or enacted by
law. All components used meet the criteria of the Florida Solar Energy Center.
6. Please refer to the attached structural calculations.
If you have any questions relating to this matter, please contact me at your
Daniel W. Dunzik, RA. LEED-AP
FL. Lic. No. AR98795
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Thank you.
Daniel W. Dunzik
370 Burnt Hill Rd. Skillman NJ. 08558
StudioGdesign@comcast.net
Gravity Load Calculation Criteria
Structural Design Loads per ASCE 7-10
Dead Loads = 10 psf+ 2.6 psf (new solar panels) = 12.6 psf
Roof Live Load = 20 psf
Ground Snow Load = 0 psf
Wind Load Calculation Criteria
Wind Loads per ASCE 7-10, Ch. 30 method 1
Using an area of 10 SF, wind loads from Figure 30.5-1:
Zone 1 = 46.1 psf Roof Slope = 1 degrees
Zone 2 = -77.3 psf Basic Wind Speed = 160 mph
Zone 3 = -116.3 psf Exposure = B
Per section 2.4.1, ASD combo = D + 0.6W:
Zone 1 = 2.6 psf+ 0.6(-46.1 psi) _ -25.1 psf
Zone 2 = 2.6 psf+ 0.6(-77.3 psf) _ -43.8 psf
Zone 3 = 2.6 psf+ 0.6(-116.3 psf) _ -67.2 psf
Architect LEED-AP
908-872-3664
January 10, 2020
Roof Mean Height = 15 ft
Check Attachment to Wood Rafter
Use 5/16 dia. Lag screw w/ 3" embedment into 2 in. wide roof rafter
Lag Screw Spacing: Lag Screw Tributary Area:
Zone 1 = 48" o.c. max Zone 1 = (48" o.c. max)A2 / 144 = 16 SF
Zone 2 = 24" o.c. max Zone 2 = (24" o.c. max)A2 / 144 = 4 SF
Zone 3 = 24" o.c. max Zone 3 = (24" o.c. max)A2 / 144 = 4 SF
Lag Screw Forces: W = 266lb/in (Table 12.2A, 2015 NDS)
Zone 1 = 25.1 psf x 16 SF = 402 lb < W', OK Cd = 1.6 (Table 2.3.2, 2015 NDS)
Zone 2 = 43.8 psf x 4 SF = 175 lb < W', OK Ct = 1 (Table 2.3.3, 2015 NDS)
Zone 3 = 67.2 psf x 4 SF = 269 lb < W', OK W' = W x embed x Cd x Ct
W' = 266 lb/in x 3 in. x1.6 x 1 = 1276.8 lb