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Floodplain Design, Construction, and Impacts On Flood Insurance
AIA/CES Registration
Architectural Record is a registered provider with The American Institute of Architects Continuing Education Systems. Credit earned on completion of this program will be reported to CES records for AIA members. Certificates of completion for non‐AIA members are available on request.
This program is registered with the AIA/CES for continuing professional education. As such, it does not include content that may be deemed or construed to be an approval or endorsement by the AIA of any material of construction or any method or manner of handling, using, distributing, or dealing in any material or product.
Copyright Notice
This presentation is protected by US and international copyright laws. Reproduction, distribution, display and use of the presentation without written permission of the speaker is strictly prohibited.
Course Description
Floods are the #1 natural disaster in the United States. All 50 states have experienced floods or flash floods.Due to climate change and other factors, flood events are increasing in number and intensity. To protect the health, safety, and welfare of homes and their occupants during a flood event, homes must be built into compliance with local, state, and federal codes and regulations.
This course describes floodplains and the potential hazards to buildings. Unless there are flood openings that allow floodwaters to flow into and out of enclosures below the Base Flood Elevation, hydrostatic pressure builds up on the foundation walls and can cause major damage. The course also defines the differences in engineered and non‐engineered flood openings and their ability to ensure resilient structures. It explains the differences between wet floodproofing and dry floodproofing techniques, and when they are applicable.
It also clarifies the regulations, codes, and standards as they relate to sustaining foundations in flood hazard areas. This course analyzes the role of building compliance in lowering flood insurance rates and what mitigation solutions are available to existing structures.
Learning Objectives
By the time you have completed this educational unit, you will be
able to:
• Describe floods, floodplains, and the potential hazards to buildings
• Explain the differences between wet and dry floodproofing techniques
• Identify regulations, codes, and standards as they relate to sustaining foundations in flood hazard areas
• Define the differences in engineered and non‐engineered flood openings and their ability to ensure resilient structures
• Analyze the role of building compliance in securing lowering flood insurance rates and what mitigation solutions are available
FEMA Best Practice Story Video
Course Outline
Section 1Floods, floodplains,
and building foundations
Section 2Wet vs. Dry
Floodproofing
Section 3Regulations, codes,
and standards
Section 4Flood openings for building resilience
Section 5Building complianceand insurance rates
Section 1FLOODS, FLOODPLAINS, AND BUILDINGS
Basic Terms
• Base Flood Elevation (BFE): The calculated level flood waters will rise during a Base Flood
• Special Flood Hazard Area (SFHA)
‐ AE & A1‐30 Zones: Have established BFE’s and low impact from waves
‐ VE & V1‐30 Zones: Have established BFE’s and impact from storm induced waves.
Note: Both A and V zones subject to experiencing a 1% annual chance flood event. This translates to a 26% chance of flooding over the life of a 30‐year mortgage.
• Freeboard: Elevating a building’s lowest floor above and beyond BFE. This is a built‐in safety factor resulting in lower flood insurance premiums. This elevation is required in certain communities with height requirements that vary.
Flood Zone Determination
Flood Zones change over time. Here are resources to determine if a property is located within a Flood Zone and the Base Flood Elevation (BFE):
• FEMA Flood Map Service Center (MSC)• Flood Insurance companies• Hydrology Firms• Other websites that specialize in this
The Cost of Flooding: Contents
Calculation for 1 in. flood in 2,000 sq. ft. home built on slab foundation.
Source: National Flood Insurance Program Flood Calculator
Effects of Lateral and Vertical Hydrostatic Force
Hydrostatic force is so damaging that NFIP Regulations state that a community shall:
“Require, for all new construction and substantial improvements, that fully enclosed areas below the lowest flood that are usable solely for parking of vehicles, building access, or storage in an area other than a basement and which are subject to flooding shall be designed to automatically equalize hydrostatic flood forces on exterior walls by allowing for the entry and exit of floodwaters.”
Title 44 of the Code of Federal Regulations, in Section 60.(c)(5)
Emergency Operation Plan – TB-3 pg. 4-5
• Establish the chain of command & responsibilities
• Procedure for notifying necessary parties
• A list of specific duties & location of all dry floodproofing materials
• Evacuation plan: with and without duties
• Annual training drills with community officials
Annual Inspection & Maintenance Plan – TB-3 pg. 5
• Mechanical equipment, sump pumps & generators
• Inspect & test all flood shields (check gaskets)
• Inspect foundation walls for cracks
• Levees & berms
NFIP Requires For Dry Floodproofing Credit
• Floodproofing Certificate
• Written certification that the Engineer of Record (EOR) design & construction meet ASCE‐24 standards
• Comprehensive Maintenance Plan– Checking gaskets, gates and barriers
• Emergency Action Plan
• Certification from the Authority Having Jurisdiction (AHJ) that they have inspected and issued CO
Floodplain Impact Consideration
• Increased flood depths, velocities, and flows
• Growing the floodplain
• ASFPM: No Adverse Impact
– The action of one property owner or community does not adversely affect another
– The goal is to prevent the growth and spread of the floodplain
Wet Floodproofing
Elevation for New Construction and Substantial Improvements
• Zone A must have the lowest floor elevated to or above the BFE.
• Zones V must be elevated on pilings and columns so that the bottom of the lowest horizontal structural member of the lowest floor is elevated to or above the BFE.
• Elevation techniques
Wet Floodproofing (Relieve) Required for Residential
• Flood Openings equalize the hydrostatic pressure
• Used in both residential and non‐residential structures
• For new construction or substantial improvements to existing buildings
• Required in A, AE, A1‐A30, AO, & AH Zones
• Required within Breakaway Walls in V‐Zones per ASCE 24
• ICC‐ES Certified Options
Purpose of a Flood Opening
Considerations for Floodproofing Strategy
Non‐Residential Considerations:
• Wet vs. Dry
• Design differences and costs
• Active vs. passive approaches and techniques
• Local floodplain ordinances
• Health, safety, and welfare of the occupants
• Costs, Liability, Impacts
Residential Must Wet Floodproof
REGULATIONS, CODES, AND STANDARDSSection 3
Floodplain Design and Construction Regulations, Codes & Standards
ASCE 24FEMA TB 3‐93FEMA TB 1‐08 IRC® IBC®
Definitions: What Is an Enclosure?
“Enclosure: That portion of an elevated building below the lowest elevated floor that is either partially or fully shut in by rigid walls.”
— Flood Insurance Manual
FEMA TB‐1 Page 6
Definitions: Crawlspaces
Definitions: Full Height Enclosures, Townhouses
Definitions: Attached Garages
Definitions: Detached Accessories (Regulated as Enclosures)
Regulated as Enclosures
Floodplain Design, Construction, and Flood Insurance Solutions
Definitions: Enclosures in V-Zones
ASCE 2.7.1.1 Openings in Breakaway Walls
Openings to allow the automatic entry and exit of floodwaters during design flood conditions shall be installed in breakaway walls in all flood hazard areas.
FLOOD OPENINGS FOR RESILIENCESection 4
• It relieves (rather than resists) hydrostatic pressure on foundation walls during a flood event. The flood vent must allow for the automatic entry and exit of flood waters without human intervention
• Passively equalizes hydrostatic loads on enclosure walls below the BFE
• Must allow bi‐directional relief of the flood waters regardless of the direction of flow
• Use of foundation flood vents in known as a "wet floodproofing” technique
• Engineered & Non‐engineered Options
What is a Foundation Flood Vent?
Documented In
Non-Engineered Openings
• “Not designed” flood openings
• Come equipped with obstructions to flow as there is a minimum screen requirement per code
• Should provide 1 sq. in. of NET open area for every 1 sq. ft. of enclosed area
• An 16 in. x 8 in. hole with air vent device inserted does NOT provide 128 sq. in. of open area
• You must account for obstructions to flow
• Liability rests with design professional, surveyor, construction official
NEW ASCE 24-14 Standards Further Clarify
This covering and other louvers, blades, grills and faceplates put air vents into a partially obstructed category which carries a coefficient of discharge of .20. Using .20 in the calculations yields A= .83 sq.in for every 1 sq. ft. of area which is rounded to 1 sq. in. of net open area for every 1 sq. ft. of enclosed space.
Engineered Vent vs. Non-Engineered Opening
• Example of an Engineered Flood Vent —It has 200 sq. ft. of rated flood protection.
• Example of a Non‐Engineered Opening —It has 42 sq. in. net, if permanently disabled in the open position.
The Math on Non-Engineered Vents
• Footprint is 30 ft. x 40 ft. = 1,200 sq. ft.
• 1200/42 sq. in. = 29 total vents required
Unacceptable Measures
According to FEMA TB‐1, unacceptable measures that will not qualify as flood openings include:
• Standard foundation air ventilation devices that can be closed manually, unless they are permanently disabled in the open position
• Standard foundation air ventilation devices that are designed to open and close based on temperature.
• Windows below the BFE
• Garage doors without openings installed in them
• Standard exterior doors without openings installed in them
Debris is a Fact of Flood
Non-Engineered Openings: Issues
According to FEMA TB‐1 pg. 20: "Non‐Engineered Openings: Communities that administer the IBC or the IRC should note the requirement to cover ventilation openings to keep animals and insects from entering. The commentaries that accompany those codes note that some covering materials may reduce the gross open area of the vent by as much as 50 percent.”
Pictured: Typical air vent clogged by flood debris
Photo Credit: FEMA TB 1 ‐08
ASCE 24: Commentary pg. 45
Engineered Openings
A Performing Engineered Opening mechanically operates, automatically activated to reveal an un‐obstructed opening during design flood with a minimum unobstructed opening of 3”.
Because a rodent screen is required by ICC code for any under floor opening it requires a Engineered Opening to go from a obstructed opening to a unobstructed opening when activated.
Flood door closed, obstructing the opening.
Flood door activated, reveals an un‐obstructed opening.
Engineered Openings: Passive Relief
• Engineered Opening – An Engineered Opening is a mechanical opening, which is activated by water during a flood revealing an unobstructed area for which floodwater can flow through to equalize the hydrostatic loads on the enclosure wall.
• These openings are performance tested and certified to cover a square footage amount. They have an ICC‐ESCertificate.
Pictured: Engineered flood vent following Hurricane Ida (2009)
ICC-ES Engineered Openings
• Designed, Tested, & Certified for performance
• Designed and certified based on computations (TB1 and ASCE 24)
• ICC‐ES Certified: AC‐364 (MOFV)
• 3”min dimension for debris flow
COMPLIANCE AND INSURANCE RATESSection 5
National Flood Insurance Program (FEMA)
• NFIP (National Flood Insurance Program)Managed by FEMA, the Federal Emergency Management Agency of the US Government
• An objective of the NFIP is to protect buildings constructed in floodplains from structural damage caused by flood forces
• NFIP Regulations include building design criteria that apply to new construction and substantial improvements to existing buildings in Special Flood Hazard Areas (SFHAs).
• Nearly 20,000 communities participate in the NFIP by enforcing floodplain management ordinances. In exchange, the NFIP offers federally backed flood insurance.
• High Risk = High Premium
NFIP Components and Coverage Limits
The NFIP balances three related program areas:
– Flood Hazard Identification (mapping)
– Flood Insurance (provision of low‐cost insurance for property owners in participating communities)
– Floodplain Management (regulations such as building codes and zoning)
NFIP Coverage Limits
• One to four‐Family Structures– $250,000 building– $100,000 contents
• Business structures – $500,000 building– $500,000 contents
Why NFIP Reform
Goal: Become Fiscally Sound Again
• 2005 (Katrina): Premium generated $1.9 billion
• 2012 (Sandy): Premium generated $3.3 billion
Changing Landscape
• 2012 Biggert ‐ Waters Reform (BW‐12)
• 2014 Grimm – Waters AKA: Homeowner Flood Insurance Affordability Act (HFIAA)
• Actuarial Rates Phased in – Non‐Primary Residences– Severe Repetitive Loss – Business Properties18‐25%
FEMA Recommends
What Can Be Done to Lower Costs?For home owners and business owners:
• Talk to your insurance agent about your insurance options
• You will need an Elevation Certificate to determine your correct rate
• Consider incorporating flood mitigation into your remodeling or rebuilding– Building or rebuilding higher will lower your risk and could
reduce your premium– Consider adding vents to your foundation or using
breakaway walls
• Talk with local officials about community‐wide mitigation steps
Key to Success: Think Like an Insurance Agent
Mitigation Works
Flood Loss Control Solutions
Proper Flood Openings Raising Mechanicals Freeboard Eliminating Subgrade Spaces
Incredible Savings After Mitigation 83%ROI: 2 YearsIn many cases clients receive refund checks for that years policy.
Freeboard: Flood Insurance Premium Discounts
Average NFIP Rates ($250,000 structural and $100,000 contents with a $1,250 deductible): This is based on a crawlspace building – where the crawlspace is adequately vented and the rate is from the first habitable floor, and there are 2 habitable floors.
‐4 $7,775.00‐3 $6,285.00‐2 $4,265.00‐1 $3,185.00
0 $1,585.00
+1 $885.00 44% decrease+2 $680.00 57% decrease+3 $610.00 61% decrease+4 $605.00 62% decrease
Elevation Certificates
• Last check point before CO is granted• Surveyor completes• Sections A8 & A9 flood vent info• EC required for actuarial rating
Required For:1. Building Department for compliance2. Flood Insurance Rating
Top Issues That Cost Clients‐ Non‐compliant Flood Openings‐ Sub‐grade spaces‐ Not utilizing enclosed areas correctly (finishing)
EC is needed to identify non‐compliance and offer mitigation options to lower risk.
EC Documentation
Summary: Mitigation for Lower Insurance Rates
• Flood Loss Control Solutions: – Eliminate Sub Grade Spaces– Raise Mechanicals– Free Board– Install Proper Flood Vents– Elevation Certificate Documentation
• Buildings constructed in compliance with NFIP standards:– Suffer approximately 80% less damage annually than those not in compliance*– Achieve greater resiliency – Receive lower NFIP Flood Insurance ratings which translates into lower premiums than those not in
compliance
* Source: www.floodsmart.gov
Case Study: House Lifted 4 ft. Above BFE
• Lifted Home in 2004
• Primary Residence
• Current BFE 8 ft.
• Has paid over $15,000 for NFIP Insurance over 10 years
“Bingo” Needs Vents
Retrofitting (6) ICC‐ES Certified Engineered Flood VentsCost: $2,500
House Lifted 4’ Above BFE
BFE 8’
Bottom Floor 3.5’ (‐4) Rating
House Lifted 4’ Above BFE
Next Higher Floor 11.7’ With Retrofit (+4) Rating BFE 8’
Bottom Floor 3.5’ (‐4) Rating
Result
+4 Rating86% ReductionROI: 1.5 years
Old Premium = $2,038 New Premium = $281
10 year total for coverage should have been: $2,810*Actually Paid: $15,000+
Thank you!
Thank you for your time.
This concludes the AIA Continuing Education System Program.
Questions? Contact us at: www.smartvent.com
Phone: 877‐441‐8368
Email: [email protected]
86
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Impact Testing
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Vehicular Entrance Application
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View 2
A Flex‐Wall™ is stored in each of the containers, and a joining wall is added between the container and the yard wall. Bollards are added to help support the wall when deployed so that it doesn’t impact the gate.
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Point of Use Storage (Side Deploy)
Storage Container with Hinged Door open
End Post
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View 4
Cables are drawn from the opposite side container and attached to the center post. The cables are then tensioned using the ratchet mechanism on the center post.
View 3
Cables are drawn from the container on the left and attached to the center post.
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View 6
The Flex‐Walls™ are drawn from the containers and attached to the center post. Each panel overlaps itself at the width of the center post to augment sealing.
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