Floodplain Design, Construction, and Impacts On Flood Insurance

Transcription

1 Floodplain Design, Construction, and Impacts On Flood Insurance

2 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.

3 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.

4 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.

5 Learning Objectives Describe floods, floodplains, and the potential hazards to buildings Explain the differences between wet and dry floodproofing techniques By the time you have completed this educational unit, you will be able to: 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

6 FEMA Best Practice Story Video

7 Course Outline Section 1 Floods, floodplains, and building foundations Section 5 Building compliance and insurance rates Section 2 Wet vs. Dry Floodproofing Section 4 Flood openings for building resilience Section 3 Regulations, codes, and standards

8 Section 1 FLOODS, FLOODPLAINS, AND BUILDINGS

9 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.

10 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

11 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

12

13

14

15 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)

16

17

18

19

20

21 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

22 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

23 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

24 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

25 Wet Floodproofing

26 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

27 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

28 Purpose of a Flood Opening

29

30 Considerations for Floodproofing Strategy Residential Must Wet Floodproof 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

31 Section 3 REGULATIONS, CODES, AND STANDARDS

32 Floodplain Design and Construction Regulations, Codes & Standards FEMA TB 1 08 FEMA TB 3 93 ASCE 24 IRC IBC

33 Definitions: What Is an Enclosure? FEMA TB 1 Page 6 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

34 Definitions: Crawlspaces

35 Definitions: Full Height Enclosures, Townhouses

36 Definitions: Attached Garages

37 Definitions: Detached Accessories (Regulated as Enclosures) Regulated as Enclosures

38 Definitions: Enclosures in V-Zones ASCE 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. Floodplain Design, Construction, and Flood Insurance Solutions

39

40

41

42

43 Section 4 FLOOD OPENINGS FOR RESILIENCE

44 What is a Foundation Flood Vent? 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

45 Documented In

46

47 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

48 NEW ASCE 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.

49 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.

50 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

51 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

52 Debris is a Fact of Flood

53 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. Photo Credit: FEMA TB 1 08 Pictured: Typical air vent clogged by flood debris ASCE 24: Commentary pg. 45

54 Engineered Openings Flood door closed, obstructing the opening. 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 activated, reveals an un obstructed opening.

55 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 ES Certificate. Pictured: Engineered flood vent following Hurricane Ida (2009)

56 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

57

58

59

60

61

62

63

64

65

66 Section 5 COMPLIANCE AND INSURANCE RATES

67 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

68 NFIP Components and Coverage Limits The NFIP balances three related program areas: NFIP Coverage Limits 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) One to four Family Structures $250,000 building $100,000 contents Business structures $500,000 building $500,000 contents

69 Why NFIP Reform Goal: Become Fiscally Sound Again 2005 (Katrina): Premium generated $1.9 billion 2012 (Sandy): Premium generated $3.3 billion

70 Changing Landscape 2012 Biggert Waters Reform (BW 12) 2014 Grimm Waters AKA: Homeowner Flood Insurance Affordability Act (HFIAA) 18 25% Actuarial Rates Phased in Non Primary Residences Severe Repetitive Loss Business Properties

71 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

72 Key to Success: Think Like an Insurance Agent

73 Mitigation Works Flood Loss Control Solutions Proper Flood Openings Raising Mechanicals Freeboard Eliminating Subgrade Spaces Incredible Savings After Mitigation 83% ROI: 2 Years In many cases clients receive refund checks for that years policy.

74 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, $6, $4, $3, $1, $ % decrease +2 $ % decrease +3 $ % decrease +4 $ % decrease

75 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 compliance 2. 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.

76 EC Documentation

77 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:

78 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

79

80

81 Bingo Needs Vents Retrofitting (6) ICC ES Certified Engineered Flood Vents Cost: $2,500

82 House Lifted 4 Above BFE BFE 8 Bottom Floor 3.5 ( 4) Rating

83 House Lifted 4 Above BFE Next Higher Floor 11.7 With Retrofit (+4) Rating BFE 8 Bottom Floor 3.5 ( 4) Rating

84 Result +4 Rating 86% Reduction ROI: 1.5 years Old Premium = $2,038 New Premium = $ year total for coverage should have been: $2,810 *Actually Paid: $15,000+

85 Thank you! Thank you for your time. This concludes the AIA Continuing Education System Program. Questions? Contact us at: Phone:

86 Dry Floodproofing Partner 86

87 Flood Protection Resilient Tunnel Plugs Flex-Gate Stairwell Vertical Flex-Wall Flex-Cover RTP Flex-Gate Portal Side Deploy Flex-Wall Pipe Plugs Plugs Flex-Gate Portal Gates Covers Flex-Wall Walls ILC Dover Proprietary Information 87

88 Side Deployed Flex-Wall (Clamped Skirt) 12 tall x 16 wide wall challenged with 10 of water Skirt is anchored to ground with clamping plates Deployment in 20 minutes with 2 people ILC Dover Proprietary Information 88

89 Flex-Wall ILC Dover Proprietary 89 Mount Posts Packed in Trench Raise Flexible Wall & Tension Remove Covers Point of Use Storage (Vertical)

90 Packing Volume Approximately 8ft of highly reinforced wall fits into a volume of 8in x 8in The wall can be rolled, Z Folded (as shown), or packed randomly The wall is comprised of a high strength webbing net (impact and water load capable), and a coated fabric water barrier

91 Impact Testing 4 tall (5 to bottom of trench) x 16 wide wall challenged with 3 of water 8ft spans tested, but wider spans possible Deployment in 10 minutes with 1 person Leakage: Measured 0.10 GPM per linear foot of seal at 3ft challenge (4ft pressure head at base of trench). Requirement of 0.5 GPM per linear foot (MTA DG 312). 91 ILC Dover Proprietary Information

92 Vehicular Entrance Application

93 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. Storage Container (each side) New Bollards View 1 A center post is removed from the container and bolted to a ground receiver at mid span. View 2 ILC Dover Proprietary Information 93

94 Point of Use Storage (Side Deploy) Storage Container with Hinged Door open End Post Flex Wall Guide Wire Cable (Option) (middle and bottom Cables and Center Support Post not shown but would be here as well)

95 Cables are drawn from the container on the left and attached to the center post. View 3 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 4 ILC Dover Proprietary Information 95

96 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. View 5 The skirt, which is attached to the Flex Wall panels during deployment, is detached from the wall and positioned. Ballasting on the skirt or bolting it to receivers hold it in place and apply pressure to a sealing material on the bottom of the skirt. View 6 ILC Dover Proprietary Information 96

97 Flex Wall Seal

98 Flex Gates

99 Vertically Deployed Flex-Wall

100 Stored in Place

101 Flex-Wall Deployed

102 Flex-Wall Vertical System is stored in a trench with a plate to conceal

103 1 st Step of Installation is to remove plates

104 2 nd step is to install any required strengthening posts. This will vary per project requirements

105 Final step is to attach Flex-Wall via plates and bolts to received hardware attached to building