Presentation on theme: "Understanding Active and Passive Floodproofing Options for Non-Residential Buildings in a Special Flood Hazard Area Course Number: SV003 Learning Units:"— Presentation transcript:
1 Understanding Active and Passive Floodproofing Options for Non-Residential Buildings in a Special Flood Hazard AreaCourse Number: SV003Learning Units: 1Credit Designation: HSWProvider: Smart Vent Products, IncProvider number: T058
2 Learning ObjectivesIdentify the applicable ICC building codes and FEMA regulations pertaining to non-residential floodproofing options.Understand the design benefits for each dry floodproofing and wet floodproofing option.Identify design issues and occupants risks associated with active flood proofing techniques and the liability associated with those risks.Analyze the difference between Active and Passive floodproofing techniques and how they affect the buildings sustainability.
3 Course Outline Section 1 General Overview Section 2 Dry Floodproofing Effects of hydrostatic pressureNFIP (FEMA) Regulations, ICC building codes, ASCE standardsDefine dry and wet floodproofing techniquesActive and passive methodsSection 2 Dry FloodproofingPlanning considerations & engineering requirementsActive vs Passive methodsFEMA floodproofing certificateDesigner LiabilitySection 3 Wet FloodproofingOptionsEngineered vs non-engineeredICC-ES Evaluated ProductsProject Studies
4 Section 1 Section 1 Effects of hydrostatic pressure NFIP (FEMA) Regulations, ICC building codes, ASCE standardsDefine dry and wet floodproofing techniquesActive and passive methods
5 Hydrostatic PressureWhat we are mitigating against in floodplains is hydrostatic pressure.This is the force that water at rest exerts on any submerged object
6 The Effects of Hydrostatic Force BA, B, C, and D photos show different types of damage that has occurred to foundation walls from hydrostatic pressure.Action Photo A shows a wall that caved in due to excessive pressure on the outside of the wall. The pressure was not equalized with water on the inside of the structure. (Outside Lateral Force)Action Photo B shows a wall that exploded out due too excessive pressure on the inside. Water got into the foundation on the rising flood, but could not get out quickly enough on the recede to equalize pressure. This illustrates the importance of bi-directional venting.(Inside Lateral Force)Action Photo C illustrates the effect of vertical or buoyancy forces on a structure. This home was lifted off of its’ slab and dropped in the middle of the street as the flood receded. (Vertical Force) For dry floodproofing designs careful attention must be given to resisting buoyancy, designs should include helical anchors.Action Photo D shows shearing of a block foundation wall from floodwater, another example of vertical forces. Home was lifted up off of the foundation and floated in place. When the house settled back down on the foundation the top block was shifted off of the next course of blocks by 1.5+ inches. The top course of block was properly bonded to the sill plate.CD
7 Floodproofing Options: A Zones Dry Flood ProofingWet Flood ProofingNon-ResidentialDry Floodproofing to “resist”Wet Floodproofing to “relieve”
8 Dry Floodproofing (Resist) Making a building watertight, impermeable to flood watersNFIP allows in non-residential buildings onlyFor new construction or substantial improvements to existing buildingsAcceptable in A, AE, A1-A30, AO, & AH ZonesDesign must be certified (Liability)FEMA’s requirements for Non-Residential floodproofing are found in Technical Bulletin 3-93Dry floodproofing is not permitted in residential structuresAllows the design to have a lowest floor below the BFE provided that the building has been designed, constructed and certified to be floodproofedNot allowed in Coastal Hazard Areas, Zone V, VE, or V1-V30Dry-floodproofing certificate discussed in a upcoming slide
9 Wet Floodproofing (Relieve) Flood Vents equalize the hydrostatic pressureNFIP allows in both residential and non-residential structuresFor new construction or substantial improvements to existing buildingsAcceptable in A, AE, A1-A30, AO, & AH ZonesICC-ES Certified OptionsThe wet floodproofing requirements are found in FEMA’s Technical Bulletin 1-08
10 Additional Floodplain Construction References 2009 IBCASCE 24-05IBC: structural design chapter 16 Section Flood Design Data. For buildings located in a flood hazard area’s per section the design must meet section requirements.requires that: (Design Plan Example in Next Slide)The design plans show the elevation of the proposed lowest floor, including the basement.The elevation to which any nonresidential building will be dry flood proofedIn V-Zones show the elevation of the bottom of the lowest horizontal structural member of the lowest floor.IBC states how you will identify if a construction lot is in a floodplain.states that it’s the municipalities responsibility to adopt flood hazard maps, these maps will show the special flood hazard areas for the community. These SFHA’s areas were identified by FEMA during a “Flood Insurance Study” which are also identified on a FIRM.The design documentation requirements:Must be prepared and sealed by a registered design professional and submitted to the community official for approval. 1.1 For A-Zones you must document the lowest flood elevation, 1.2 State the use of flood openings (references to ASCE 24) discuss attaching our ICC-ES report, 1.3 if you opt to use dry-floodproofing measures you must certify that the design is in compliance with ASCE 24 a FEMA floodproofing cert is also required.ASCE 24-05Dry & Wet Floodproofing requirements.
11 Design PlansThe pictured drawing shows the first floor elevation and the 100 year floodplain elevation. The blue area identifies the floodplain all the way through the building. 2 foot of freeboard was designed in.This project utilized flood vents
12 Which To Design With? Dry Vs Wet Design differences and costs Active vs Passive approachesChoosing the right floodproofing measure for the design.
14 Dry Floodproofing Planning: Is it possible? Considerations Warning time, Safety & AccessFlood Velocities, Depths, and DebrisFrequencyEmergency PlanInspection & Maintenance PlanCostLiabilityThings to consider before jumping into a dry floodproofing design careful study of the site and the following factors must take place to see if dry floodproofing is appropriate.if the site will be surrounded by rapidly rising, high velocity flood waters and the warning time is short then the site is not suitable for a dry floodproof design.
15 Warning Time, Safety & Access Time is criticalActive flood proofing measuresHuman StabilityDry Flood Proofing is not appropriate in a flash flood area.Page 3 TB-3*Warning Time, Safety & Access to the building is the first consideration for your design.You must review the rate of rise of the floodwaters for the site in questioned to determine how much time there will be to evacuate a building and how much time to install dry floodproofing measures such as flood shields and gates, close valves, etc(Actions 1 & 2)Time is critical because floodwater can sneak up on you and you need to allow enough time for people to safely exist the building. The design needs to be sound and exists for the building should not be under water.Back in 1987 Colorado State University conducted a study on human stability in a flood flow, if the base flood product number is 4 or greater (depth in feet multiplied by velocity in feet per second) it will create a hazard for anyone attempting to escape from or gain access to the site.(Action 3 & 4)Big issue with Active dry floodproofing products (Requiring Human Intervention) is the need for people to be present before the flood to install the devises to protect the building.Man power is needed to install the pictured floodproofing shields, time is also needed to get these barriers in place, putting people at risk.Do not use dry floodproofing measures in a flash flood area.
16 Flood Velocities, Depths & Debris Cost Prohibitive WhenFlood Velocities are over 5 feet per secondBase Flood depths in excess of 3 feetImpact forces from debrisCalculation assumes 1 second duration of impactObject estimated at 1,000 poundsSecond step considerations.If the flood velocities are in excess of 5 feet per second or the flood depths of the water are shown to exceed 3 feet during a base flood then dry floodproofing becomes cost prohibitive. In a upcoming a slide while discussing minimum engineering requirements we will show a chart regarding water depth and the hydrostatic pressures you need to account for in your designs.(First Action)You can pull the food velocity for a area by referencing the cross section on a communities FIS. From here you will only be able to see the velocities in the floodway, the Floodway mean velocity will yield the highest velocity number for the floodplain. If you wanted site specific velocities, you would get a copy of the modeling in HEC-RAS and look at the cross section with the velocity distribution. (Image included as first action)What is a FIS?A Flood Insurance Study (FIS) is a book that contains information regarding flooding in a community and is developed in conjunction with the Flood Insurance Rate Map (FIRM). The FIS, also known as a flood elevation study, frequently contains a narrative of the flood history of a community and discusses the engineering methods used to develop the FIRMs. The study also contains flood profiles for studied flooding sources and can be used to determine Base Flood Elevations for some areas. (Second Action) Page 4Because of the additional risks of dry flood proofing, a 1 foot freeboard must be designed in for all dry floodproofing measures. All though for floodplain management purposes the structures floodproofing only needs to meet the BFE, for the increased risk the NFIP subtracts 1 foot from the elevation. So if the building is only dry flood proofed to the BFE the NFIP will rated as if its 1 foot below BFE with its floodproofing protection. In these cases the flood insurance rate will be extremely high.Additional freeboard may be required by local ordinance, which will require additional material costs.
17 Flood Frequency How often Wear & Tear Risks of implementing a emergency plan over and overIf frequency is not a factor, time to designPg 4 Tb-3Last check point before moving a head with a dry floodproof design is flood frequency.If the area floods frequently it can cause wear and tear on a structures external components and can compromise the structural integrity of the building.There are also risks of implementing a emergency operation plan over and over.To determine flood frequency you can refer to USGS and other references for analysis on flood frequency. (River)To better understand frequencies of flooding, depths and velocities you can work with a engineering firm that specializes in hydrologyHydrology is the study of the movement, distribution, and quality of waterA practitioner of hydrology is a hydrologist, working within the fields of earth or environmental science, physical geography, geology or civil and environmental engineering.John A. Miller, P.E.*, CFM, CSM Water Resources Engineer Certified Floodplain and Stormwater Manager Princeton Hydro, LLC 1108 Old York Road Suite 1, PO Box 720 Ringoes, New Jersey t x110 c f If warning time, safety & access, flood velocities & Depths, and flood frequency is not a issue then dry flood proofing is a option.
18 Emergency Operation Plan Establish the chain of command & responsibilitiesProcedure for notifying necessary partiesA list of specific duties & location of all dry floodproofing materialsEvacuation plan- with and without dutiesAnnual training drills with community officialsPg 4 & 5 of TB3 Design Professional must produce the planThe emergency operation plan is critical when flood proofing requires human intervention.The plan is required to ensure that the floodproofing components will operate properly under all conditions, including a power failure which is often seen during floods. A continuous source of electricity will be needed to ensure that sump pumps are able to operate, this will require the need for a back up generator or a battery back up for the pump. Pumps are required in all dry floodproofing designs.The above listed items on the slide make up a good plan.
19 Inspection & Maintenance Plan Mechanical equipment, sump pumps & generatorsInspect & test all flood shields (check gaskets)Inspect foundation walls for cracksLevees & bermsPg 5 of TB3Plan should take place annually at a minimumThe inspection and maintenance plan should cover the above listed components.Action 1 will bring up a flood gate diagram of checkpoints.Both the emergency and and inspection plans must be submitted with the dry floodproofing certificate. Before permits are granted the community official should require the property owner to sign an agreement stating that the plan will be adhered to. The agreement will also include language regarding change of ownership. And any lease agreements will contain lease holders responsibilities for the floodproofed building.
21 Property AddressBuilding Location and ownership info
22 Section I & IISection I: is for the Flood Insurance Rate Map info. This includes the FIRM Flood Zone and the BFESection II: is to document the elevation the building was flood proofed to. Make mention of the “note” regarding being at least 1 foot higher then the BFE with the dry floodproofing measure to receive rating credit.
23 Section IIISection III: This is the actual certification of the form as required by Section 60.3 of the NFIP regulations. The design professional signing this form are certifying that they have developed and or reviewed the design plans and specifications and find them in compliance with accepted construction standards of practice for dry floodproofing.
24 Floodplain Impact Consideration Increased flood depths, velocities, & flowsGrowing the floodplainASFPM: No Adverse ImpactThe action of one property owner or community does not adversely affect anotherOne last consideration, how will the design affect the floodplain?ASFPM: Mission Statement (Goal) to prevent the growth of the floodplain.
25 Section 3 Wet Floodproofing (Passive Solution) Engineered vs Non-engineeredICC-ES Evaluated ProductsProper PlacementWet floodproofing is less impactful to the over all floodplain as we are elevating and letting the water take its natural course.
26 Three Options ICC-ES Certified Engineered Openings Unique project specific Engineered OpeningsNon-engineered OpeningsBoth FEMA and the ICC reference ASCE 24.ASCE requires that flood openings allow for a 3” sphere to pass through to permit for debris.Everyone at this point should put away TB-3 and pull out TB-1 to following along.These are the three flood venting options, we will review reverse order.
27 3. Non-engineered Openings Provide 1 sq in of net open area for every 1sq ft of enclosed areaAn 8”x16” hole with air vent device inserted does NOT provide 128 sq in!Account for obstructions to flowIf I-Codes apply, 3” min dimensionLiability: Design Professional, Surveyor, Construction Official#3 optionGoing from worst to firstNon-engineered openings meet the method of 1 net sq/in of flood venting for every 1 sq/ft of enclosed area.Air vents are the most popular non-engineered openingsThese openings are not designed as flood openings27
28 Unacceptable Measures: Page 19 TB-1 Standard foundation air ventilation devices that can be closed manually, unless they are disabled in the open positionOn page 19 of TB-1 FEMA states certain measures that will not be acceptable as flood openings. The main reason that windows, garage doors and exterior doors do not qualify as flood openings, is because human intervention is required to open them.
29 Unacceptable Measures: Page 19 TB-1 Standard foundation air ventilation devices that are designed to open and close based on temperature
30 Unacceptable Measures: Page 19 TB-1 Windows below the BFEGarage Doors without openings installed in themStandard exterior doors without openings installed in them
31 Debris is a Fact of Flood ASCE 24 is referenced in both FEMA regulations and the International Building Codes. It requires a 3” diameter sphere to pass through the flood opening for it to comply. This is to ensure that grills and louvers do not interfere with the passage of debris.31
32 3” ClarificationThe question asked of the ICC in by Licensed Design Professional.Item of section R requires that the flood opening “shall be at least 3 inches in diameter” Does this mean that the opening must have a minimum diameter of 3 inches?Response is blown up in the slide.
33 2. Unique Engineered Openings Designed for a specific projectCertified based on computations (TB1 and ASCE 24)I-Codes & ASCE 24: 3” min dimensionNot for mass distributed productsDesign must be accompanied by the original certificationLiability: Licensed Design Professional# 2 optionThis option is available for a licensed design professional choosing to design a engineered opening to meet specific project needs, such as aesthetic reasons.
34 Unique Engineered Opening Certificate Statement certifying the openings will automatically equalize hydrostatic flood loadsRange of flood characteristics usedInstallation requirementsProperty address (must be licensed in that state)Licensed design professionals name, title, address, type of license, license number, state in which the license was issuedIf the unique (project specific) engineered opening method is used the original engineered opening certificate must include the following.Today there are a couple companies currently miss using this option and making photo copies of certificates for their air vents. Designers should be very careful of these products if they are requested to be used as a “equivalent” substitution to a ICC-ES certified engineered opening.Don’t believe everything you read online.
35 1. ICC-ES Engineered Openings Designed, Tested, & Certified for performanceDesigned and certified based on computations (TB1 and ASCE 24)ICC-ES Certifed: AC-364 (AFFV)I-Codes & ASCE 24: 3” min dimensionThe #1 option for any design should be performance tested products to ensure they will operate probably when called upon. The ICC-ES has established testing criteria for Automatic Foundation Flood Vents (AFFV)Action: Debris is part of the testing criteria, it includes in dried leaves, grass clippings and 3 inch balls. All are included to prove that the vent will not clog with debris during a flood which would leave the vent ineffective relieving hydrostatic pressure and the foundation at risk.The Evaluation Service is a subsidiary of the International Code Council.
36 ICC-ES Report Reference the ICC-ES report in the catalog Reports Lists: Name of manufacturer, different models offered, and the square feet each model is certified to cover.Action: All products certified through the ICC-ES will be clearly identified in the field with a label with the model number and certified coverage.
37 Liability For Performance Rests on the manufacturer’s shouldersEach vent is testedRegular QA inspectionsThe next few pictures are of our Anderson, SC manufacturing plant. All of our products are constructed out of 316 Marine Grade stainless steel, and are made in the USA!
38 Placement Requirements With in one foot (12”) of the adjacent grade. 1 foot is the max.
39 Placement Requirements FEMA PhotoIn this example the vents are with in 12” of the inside grade which was higher then the outside grade for each opening.If your design will have this type of application where the vents are higher then 12” of the outside grade but in compliance with the interior make sure this is noted on the plans, and the surveyor is alerted to measure from the inside.
40 Placement Requirements Vents on two different walls.Discuss that each enclosed area below the BFE must have at least two flood opening, and must be on two different walls. Internal enclosed spaces with in a larger space must also meet the same. Explain the use of flow throw openings on dividing walls to join the spaces.40
41 Sloping Sites: Walk Out Basements The interior floor along the lower side of a building that is set into a sloping site must be at or above the exterior grade across the entire length of the wall. If the exterior grade was not level or lower with the interior grade on one complete side, then the enclosed area would be classified as basement Diagram 2 on the elevation certificate this would result in a higher insurance premium.In the above example it is important to also point out that most of the vents should be placed in the lower wall as it will be the wall that needs to relieve hydrostatic loads first. Openings in this wall will also allow for the best drainage.41
42 Dry vs Wet William L. Coulbourne, P.E. Floodproofing Report Dry vs Wet Floodproofing TechnologiesTwo dry scenariosTwo wet scenarios5,000 sq. ft. spaces 4 foot BFE with 1 foot freeboard
43 Dry Scenario 1D 5,000 sq. ft. full height enclosed space 1D includes a 5000 sq/ft full height enclosed space with a concrete slab and poured concrete walls to resist water.Two 12 foot wide garage doors, needed bolt-in-place (Active) flood barriersTwo 3 foot wide entry doors, needed bolt-in-place flood barriersWalls need to be coated with a water proof membrane to prevent water leakageResistance to buoyancy is significant for 5 ft. of water depth, helical anchors were required to prevent floatation. 60,000 pounds of uplift resistance per
44 Dry Scenario 2D 5,000 sq. ft. crawlspace 2D is for a 5,000 sq/ft crawl space.No garage doors or entry doors, only two crawlspace doors.
45 Wet Scenario 1W 5,000 sq. ft. full height enclosed space (13) ICC-ES certified flood vents(13) Smart Vent 16x16 model flood vents were utilized. Each is certified to cover 400 sq. ft. each.No reinforced concrete, no helical anchors
46 Wet Scenario 2W 5,000 sq. ft. crawlspace (13) ICC-ES certified flood vents(13) Smart Vent 16x16 model flood vents were utilized. Each is certified to cover 400 sq. ft. each.No reinforced concrete, no helical anchors
47 Cost Analysis1D vs 1W: Wet is 53% ($48,157) less then Dry and no liability associated with the flood proofing measure.2D vs 2W: Wet is 67% ($50,877) less then Dry and no liability associated with the flood proofing measure.
48 Summary: Considerations Local floodplain ordinancesHealth, Safety & Welfare of the OccupantsActive vs Passive techniquesCostsLiabilitySFHA Non-residential design considerations summary, things to think through before choosing between Dry and Wet floodproofing measures.