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Certification of Engineered -Flood Openings
in accordance with NFIP, FEMA TB 1-08, and ASCE/S_E24-05 :
I hereby certify that the Crawl Space Door Systems flood vents 816CS, 1220CS, 1232CS, 1616CS, 1624CS, 1632CS, 2032CS, 2424CS,
and 2436CS are designed in accordance with the requirements of the NFIP 'Flood Insurance Manual" (2011) to provide automatic
equalization of hydrostatic flood forces by allowing for the entry and exit of floodwaters, when properly Installed and sized as set
forth below. This certification follows the design requirements and specifications established in FEMA Technical Bulletin 1-08,
'Openings in Foundation Walls and Walls of Enclosures Below Elevated Buildings In Special Flood Hazard Areas', and the A5CE
Standard for "Flood Resistant Design and Construction" (ASCE/SEI 24-05). The actual vent opening measurements were determined
and certified by Mr. Christopher Mark Loney, Virginia PE No. 029000. Calculations are based on the spreadsheet formulas, and.
"Review of certification of Engineered Flood Openings, dated January 16, 2012" prepared by Dr. Georg Reichard, Associate Professor
of Building Construction, Virginia Tech.
Design Characteristics
Section 2.6.2.2 of ASCE 24 provides an equation to determine the required net area of engineered openings (A•) for a given enclosed
area (A,). This equation Is based on the hydraulic formula for the flow rate across sharp edged orifices. 1 have utilized this equation
to calculate 1) the respected flow rate through the individual openings between louvers; 2) the flow rate through the main frame
opening In case the louver is blown out during a flood event; and 3) the flow rate of water flowing through lower blades following
hydraulic short tube theory. The ultimate maximum total enclosed area (A") that can be serviced by a single vent has then been
determined by utilizing the lowest flow rate of the three assessed scenarios for each vent and is listed in Table 1.
These values are based on the following assumptions:
• In absence of reliable data, the rates of rise and fall have been
assumed with 5 feet/hour;
• The (maximum) difference between the exterior and interior
floodwater levels has been assumed with 1 foot during base
flood conditions;
• A factor of safety of 5 has been assumed, which is consistent
with design practices related to protection of life and p2pe
• The net area of openings (A") as provided by the man(,faclurer.
Installation Requirements and Limitations
This certification will be voided if the following installation
r ui eme is d limitations are not enforced:
•)
Model
H x W
[in]
A.
[in']
A,
[ft']
❑
916C5
a x 16
106
20S
❑
122005
12 x 20
237
Soo
❑
1232C5
12 x 32
306
645
❑
1616CS
16 x 16
184
395
❑
1624CS .�:
�,,26 x-24--
:-_312-
-� 670 .._
M
1632C5
2032CS' ---20xa2=-
�6 x 3 2�
!�' *408 --
�-630
a35--"
❑
1240
❑
2424C5
. 24 x 24
570
1230
❑
2436CS
24 x 35
852
1765
r n an Table 1 Maximum total enclosed area (A•) that can be
• There shall be a minimum of two openings on different sides of served by each individual model based On the
each enclosed area; • The bottom of each required opening shall be no more than Sft given net area of engineered openings (A•)
above the adjacent ground level;
• No temporary (e.g. during cold weather) or permanent solid cover may be placed into or over the flood vent that would block
the automatic entry or exit of floodwaters at any time;
• Where analysis Indicates rates of rise and fall greater than 5 ft/hr, the total enclosed area as given in Table 1 shall be reduced
accordingly to account for the higher rates of rise and fall.
Certifying Design Professional �•Ilk11111/iilt, _
Name, ride
Steve A. Geci, President, Ged & Associates Engineers, Inc.
,`� •S•ESt• f'ae �j
• V rr1111,
� :'by d ;�
Address 2950 N le Avenue, Pensacola, FL 32503 �
• *�
No. 33858 c
License Florida Professional Engineer, ll 0.33658- '
51gna7
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STATE OF •• t�i
Identification of the Building and installed Flood Vents (By Others) -IrOVA& rN%% -
The flood vent models marked In Table 1•) are being installed at the following building:
Building Address