Floods are the most common natural disaster in the United States. We tend to think that floods happen mainly around coastlines and during hurricanes, but America is experiencing more frequent and devastating floods along creeks and rivers (“riverine floods”), lakes and ponds, and areas with inadequate drainage systems. In some cases, extreme precipitation events (“atmospheric rivers”), in-land tornados, and melting snow/ice can also cause floods in unexpected locations.

Although Texas, New Orleans, and Florida are known for their massive flooding experiences following hurricanes, many other regions in America experienced severe flooding throughout the years. Massive floods have occurred along the Mississippi river hitting communities from Illinois to Louisiana. South Dakota, West Virginia, Oregon, and others experienced flash floods from heavy rains.

All these historical floods left behind life casualties, broken families, and displaced communities. While many lessons have been learned and many solutions have been implemented, recent events imply the future is lining up bigger challenges.

Failing to prepare for future floods can lead to loss of property, injury, and death. Beyond direct damage from flood water, flood events also disrupt life by causing prolonged outages, risk zones of mud and landslides, broken supply chains of food and water, and limited transportation.

In this blog we will cover the following key strategies which may help protect your home from flood damage:

• Elevation of the home above BFE

• Adoption of Water Resistive Materials

• Building Rain Gardens and Barrier Systems

• Elevating Essential Infrastructure

• Backing up Critical Systems

• Flood vents

• Flood barriers

• Government funds/grants to mitigate risks

• Flood Insurance

• Final Thoughts

Elevation

There are many ways to deal with floods, from simply securing your valuables at the most elevated spot in your house to elevating the entire house above a “BFE” which is the Base Flood Elevation level. Many countries have flood maps that determine which locations are flood-prone and in many cases in the U.S, states and local municipalities have granular data on risks as well as corresponding building codes. The best way to plan is to hire an expert that knows the local risks and codes to properly design and build your house to protect it against excess precipitation and floods. But here are some great sources of information from FEMA (Federal Emergency Management Agency) to become familiarized with the basics:

FEMA Flood Maps

How to Prepare for a Flood and Minimize Losses

All the glossary you need to know regarding floods and construction: Glossary of Terms

Water Resistive Materials

The main concept here is to take advantage of building materials that can dry out, resulting in minimal damage and preventing decay and mold growth. This strategy is important especially in locations where there is a higher risk of flooding or hurricane damage.

Examples of flood resistive materials are preservative-treated wood framing (choosing environmentally friendly treatments like borate), fiberglass-faced rather than paper-faced drywall, and tile or resilient flooring rather than carpeting. In addition, newer materials such as fiber cement products, and certain types of metals and plastics also resist water damage.

Note: it is critical, beyond choosing the right materials that can dry, to properly design the house (foundation, walls, roof) to allow interior and exterior surfaces to dry. This has to do with the climate zone you are in, the temperatures inside and outside the house and humidity, the insulation, and airtightness applied. Not allowing vapor, precipitation, melting snow, and ice to dry quickly causes damage, and that cost (as well as risk to health and aggravation) will be repeated if not done correctly. Solution: hire professional people and make sure they walk you through the design and material choices they make and how together the house system will behave during normal conditions (per your climate zone) and during and after extreme events such as a flood.

Back to materials, there are green-friendly options that we encourage exploring, here are some to get inspired by:

• Preservative-treated wood - the preservative-treated wood’s key benefit is its resistance to water, fungal, and insect damage (e.g. termites). In addition to making your house more resilient, you are directly contributing to the environment since resilient wood requires less maintenance and provides longevity that eliminates further forest harvesting. For many years, wood was treated with chromated copper arsenate (CCA). In 2004, the EPA (the United States Environmental Protection Agency) reached an agreement to end the sale of CCA-treated wood for most wood-based products due to its toxic nature. Today, most common wood products are treated with ACQ as an alternative. However, even ACQ is considered to have risks with its copper substance. As an example, Borate-based treatments are considered safer. However, you must consult with an expert to properly match the wood to your environment as different treatments behave differently in various climate zones - humid vs. dry, hot vs cold.

• Fiberglass-faced drywall - while paper-faced drywalls are more common and affordable, they do pose a risk in humid and wet areas as they tend to develop mold. Using mold-resistant drywall (e.g fiberglass-faced) may be more expensive upfront but will provide longevity and resilience.

• Fiber cement - while wood is probably the most pervasive material used for sidings, today you can find various types of sidings such as aluminum, vinyl, stone, brick, stucco, or fiber cement. The latter is considered an eco-friendly alternative, however, it does require an expert to manage the installations, it requires ongoing treatment, it does absorb moisture, and upfront costs are higher. So before choosing any of the wood alternatives for sidings, you need to match the material to your climate zone and usage objectives within your built environment.

• Resilient flooring - basically implies avoiding carpets and wood in flood-prone zones and suggesting using more durable, water-resistant solutions. Popular solutions that fall under the green category would be Vinyl, Linoleum, Cork, and Rubber. When looking at both green and resilient, it is advised to focus on Linoleum solutions made of 100% natural substances (versus Vinyl and Rubber which in many cases use gas vomiting chemicals). It is also important to consult an expert regarding the materials used to install the floor (e.g. glue) and make sure those are also resilient and safe.

In many cases, flood resistive materials are the “go-to” solution when more expensive and complex solutions are not feasible (such as elevating the house above the Base Flood Elevation level (BFE) as mentioned above)

To figure out the risk of flood in your area, start with searching FEMA’s Flood Map Service Center.

Rain Gardens

Rain gardens are a great solution against water runoff and our way to help our community as well as our own water quality. A rain garden is a garden of native plants you can plant after observing where rainwater in your yard flows after massive rain. By digging a ditch or creating a small barrier / slope, and planting the right plants, you can help stop excess rainwater from running off and ending up overwhelming the local sewer system or water reservoirs. According to the, “rain gardens are effective in removing up to 90% of nutrients and chemicals and up to 80% of sediments from the rainwater runoff. Compared to a conventional lawn, rain gardens allow for 30% more water to soak into the ground…” and since “...rain gardens will drain within 12-48 hours, they prevent the breeding of mosquitoes.”

For further reading see:

rain gardens

When It Rains, It Pours: The Effects of Stormwater Runoff

New Orleans has dedicated a section in their NOLA-Ready website to green infrastructure. Highly recommended “go-to” website in general, the green infrastructure section mentions several strategies to develop a flood resilient community. In that section, each strategy is explained and they also indicate the amount of effort/labor, cost, and efficacy of each strategy.

Strategies mentioned are:

• Rain Garden

• Detention Basin

• Stormwater Planter Box

• Infiltration Trench

• Pervious Pavers

• Rain Barrel

• Plant Trees

Here is a link to NOLA-Ready “green infrastructure” section: Green Infrastructure - NOLA Ready

Backup and System Protection

Resilience strategies aim to either prevent damage to a building’s equipment in the event of a flood or storm surge or to provide backup and redundancy for running critical systems.

Elevated Essential Infrastructure:

This strategy helps limit the effects of flooding and storm surges on building support systems, including HVAC, fuel supply, electrical systems, and appliances by elevating essential infrastructure above the projected water elevation.

Essential infrastructure systems should be protected from floodwater and storm surges due to multiple reasons: The first, and obvious - water damage. Second, moving floodwater and storm surges also exert pressure which can damage these systems. Third, flood water often contains dissolved chemicals, silt, suspended solids, and floating debris which you want to avoid.

FEMA’s P-348 2nd edition from 2017 is a comprehensive guide for professionals that covers principles and practices for the “Design and Construction of Flood Resistant Building Utility Systems”. In other words, it is a guide that helps you protect all your utilities in the home from floods. It’s a long read but a great reference to become aware and equip yourself with ideas and knowledge when building or fixing your house.

Backing up Critical Systems

These strategies help maintain critical building functions in the event of a power outage or water supply loss.

The maintenance and operation of critical systems in the event of a power outage should be prioritized in the design of the building as well as in the operations and maintenance plans.

Critical systems should be backed up with renewable power generation, a generator, or a battery backup system. A building that has backup power generation is more resilient than a comparable building without those systems.

As for the loss of water supply, many tend to think that it is a result of a busted pipe that can be fixed in a relatively short amount of time. The truth is, we might lose water supply due to multiple environmental hazards such as storms, and the remedy sometimes, isn't as speedy as we think. There are numerous emergency backup water systems that can be installed in the house, from basic water storage tanks that you will need to replace on your own, to more sophisticated solutions that rotate the water for you.

Here are just a couple of examples:

• Home | Constant Water | Emergency Water for You and Your Loved Ones

• ReadyMadeWater - Inline Auto-Rotating Water Storage

Swedge backflow protection

Floods can inundate and overload sanitary and rain sewer systems. As a result, water can flow backward through sewer lines and out through toilets or drains. There are several backflow prevention solutions, however, please note that installation of backflow valves and other plumbing modifications may be regulated by your State and local building codes, therefore it is highly advised to consult with a licensed plumber or contractor about your options (by the way, this holds true to all topics covered in this blog).

Flood Vents

In general, we want to try to prevent water from entering our properties. Yet, trying to keep out water in cases of severe floods with high water pressure, may break and destroy walls and foundations. Instead, we can manage the flood water to enter and exit the property quickly causing as little damage as possible. This can be done by installing flood vents in enclosures below the Base Flood Elevation (BFE). This is also called Wet Floodproofing. Make sure to install engineered flood vents that are designed to operate only when needed and that critical systems are elevated. 

Flood barriers

You can place or install residential flood protection solutions such as aluminum flood shield barriers that can be mounted on doors or windows, or biodegradable sandbags, to protect from flood water entering the property. Note that these solutions protect from floods that do not exceed the height of the barriers installed. 

Unfortunately, we couldn’t find third-party certified products or environmentally friendly manufacturers. If you know of such, please contact us. 

Financial assistance for risk mitigation

Both FEMA and local governments plan and issue funds to carry out hazard mitigation projects. Hazard mitigation investments are “pre-disaster” that aims to build the resilience of communities and homes as preparation for future events.

Eligibility for most grants is at local government / community level but homeowners / individuals may apply through their community. First, check with your local representatives if your county is eligible for funding and if so, ask your community representatives to apply on your behalf.

Here is the starting point with FEMA’s HMGP- Hazard Mitigation Grant Program.

Flood Insurance

According to FEMA, floods are the most common natural disaster in the U.S, and perhaps that is the reason that most insurance companies exclude flood damages from their homeowners’ insurance coverage.

However, flood insurance can be purchased separately. In some cases, you will be required to purchase flood insurance: if your property is located in a high-risk flood area and your mortgage lender is federally regulated or insured, the lender is mandated to require flood insurance. The lender can also decide to require flood insurance even if they are not mandated to.

The National Flood Insurance Program (NFIP) provides flood insurance to property owners, renters, and businesses, to assist with a fast recovery when floodwaters recede. The NFIP insurance is mandatory in Special Flood Hazard Area (SFHA), which results in the misbelief that areas not considered SFHA, are not at high risk of a flood. This is a misperception, especially since experts consider FEMA’s flood maps to be outdated and not provide the true flood risk in some areas. The NFIP insurance can be purchased from private insurance companies which are also responsible for customer service, but the federal government is responsible for underwriting losses.

NFIP insurance provides two separate policies:

1. One for the building itself

2. A separate policy for the content of the building: personal belongings.

You can decide to purchase one or both.

We looked at flood insurance from Allstate as an example:

Building property coverage provides coverage for the physical structure of your home or non-resident property, including electrical and plumbing systems, refrigerators, window blinds, and more. The maximum coverage in this policy is $250,000.

Personal property (contents) coverage provides coverage for the items inside your home, like clothing, furniture, electrical appliances, at their value at the time of loss. This policy’s coverage is limited to $100,000.

Both policies do not cover:

• Damage caused by moisture, mildew, or mold that could have avoided by the property owner

• Currency, precious metals, and valuable papers like stock certificates

• Property and belongings outside of a building like trees, fences, and swimming pools

• Living expenses like temporary housing.

The rough average cost of flood insurance is $700. The cost differs according to factors such as the location of the property and if it is a high-risk zone, and the age of the property. You can also find calculated premium averages by State.

As of October 1st, 2021, FEMA will update the NFIP pricing methodology for the first time in fifty years. The new methodology will incorporate more flood risk variables such as flood frequency and type, distance of property to a water source, and specific property characteristics such as elevation and cost to rebuild. New policies beginning October 1st will be subject to the new rating methodology and existing policyholders eligible for renewal will be able to take advantage of immediate decreases in their premiums.

Note that flood insurance has a 30 day waiting period after the purchase before the coverage takes effect, so if you decide on purchasing flood insurance, you better not wait till the last minute.

One way to reduce the cost of your flood insurance is to enroll your community in the Community Rating System (CRS) which is an incentive program provided by the NFIP. The city of Livermore received a 20% discount on flood insurance by making their city more flood resilient.

Another way is to retrofit your house to make it more resilient to floods by exercising one of the abovementioned strategies:

• Elevating your property, or at least elevating the utilities and HVAC equipment to higher levels if possible.

• Install a sewage water backstop

• Include porous surfaces in your landscape

Final Thoughts

Floods are still the most common natural disaster in the U.S, and probably this is going to be the case in the foreseeable future.

Planning and executing flood mitigation strategies must be led by local governments and communities working together to carry out citywide planning, infrastructure preparedness, and disaster recovery plans.

However, homeowners should be informed about steps they can take towards building resilience into their own homes.

Floods traditionally happen in known risk zones however, in recent years, climate change has brought on extreme events which overwhelmed zones that were considered prepared and protected as well as catching communities out of risk zones by surprise.

As a result, homeowners need to research risk mitigation strategies, either by adopting the latest building codes and in high-risk zones consider looking at strategies that go above the building codes which are considered the minimum.

In this blog we mentioned at a very high level some of the main strategies that homeowners can adopt to better prepare against the risks of floods:

• Elevation of the home above BFE

• Adoption of Water Resistive Materials

  • That meet your climate zone as well as resist the extreme amount of water

  • Designing them properly so they dry out quickly (consult professionals)

• Building Rain Gardens and Barrier Systems

• Elevating Essential Infrastructure

• Backing up Critical Systems

• Installing flood vents

• Placing flood barriers

• Take advantage of government funds to build resilience where applicable

• Take advantage of Flood insurance where applicable

KEEP COOL. BUILD RESILIENCE. EAMPACT.

References:

• https://www.ready.gov/floods
• https://www.fema.gov/
• https://msc.fema.gov/portal/home
• https://www.floodsmart.gov/community
• https://www.fema.gov/pdf/fima/pbuffd_appendix_b.pdf
• https://msc.fema.gov/portal/home
• https://www.buildinggreen.com/feature/design-adaptation-living-climate-changing-world
• https://www.usgbc.org/sites/default/files/GreenBuildingClimResil.pdf
• https://www.groundwater.org/
• https://www.groundwater.org/action/home/raingardens.html
• https://blogs.ei.columbia.edu/2018/04/03/stormwater-runoff-rain-flood/
• https://ready.nola.gov/home/
• https://ready.nola.gov/green-infrastructure/
• https://www.usgbc.org/sites/default/files/GreenBuildingClimResil.pdf
• https://www.fema.gov/media-library-data/1489005878535-dcc4b360f5c7eb7285acb2e206792312/FEMA_P-348_508.pdf
• https://link.springer.com/article/10.1007/s10669-013-9440-y
• https://constantwater.com/
• https://www.readymadewater.com/
• https://www.fema.gov/grants/mitigation/hazard-mitigation
• Resilient Design Handbook | Jersey City | Make It Green (jcmakeitgreen.org)