Planning your build
Things To Know When Building A House In A Flood Zone
Whether you’re looking to build your dream house on the coast, construct a home with picturesque lakeside views or have found an affordable plot of land in a low-elevation area, you may not have considered the added building regulations and insurance policies required for you to live out our American dream.
In the United States, it is estimated there are over 41 million people living in flood zones. But many homes in these high-risk areas and beyond are not insured and have not been built in a way that mitigates the residential building from flood damage.
Common Causes of Flooding
Across America, there are primarily three main causes of flooding: coastal flooding, riverine flooding, and pluvial flooding. Coastal flooding refers to flooding from tide or storm surges because of hurricanes, tropical storms or other extreme weather events. Whilst riverine flooding refers to flash flooding or overbank flooding that occurs when a body of water overflows its banks or when flood defenses fail.
Finally, pluvial flooding or surface flooding refers to flooding due to stormwater and rainfall flooding, along with areas experiencing tropical depression. This type of flooding has become a widespread issue within the U.S. this year with flash flooding and rainfall flooding impacting regions such as Florida, Missouri, Illinois, Virginia, Las Vegas, St. Louis, Arizona, Phoenix and California.
But with the correct planning, paperwork and flood-proof home design, living in a flood-prone area doesn’t have to be doom and gloom. As home builders with decades of experience, in this article, our expert builders will detail some key considerations for building a home in flood-prone areas.
Understand The Risk & Requirements:
The first step when building a flood zone house design is to research and fully understand the risks and requirements associated with the project. In the United States, governing bodies such as the Federal Emergency Management Agency (FEMA) have mapped out all the regions and defined them in alignment with the level of flood risk. This is broken down into four main categories highlighted in the tables below.
Special Flood Hazard Areas (SFHA)
|Flood Risk Type||Description||Requirements|
|V Zone||The most hazardous area with a high-risk for flooding with a 25% risk of flooding||Mandatory flood insurance|
|VE Zone||Coastal areas with 1% or more chance of flooding each year||Mandatory flood insurance|
|A Zone||High risk for flooding located near water||Mandatory flood insurance|
|AE Zone (previously A1-A30 zones)||Base floodplain||Mandatory flood insurance|
|AH Zone||1% chance of shallow flooding ranging from 1 feet to 3 feet||Mandatory flood insurance|
|AO Zone||1% or more chance of shallow flooding located near a river or a stream||Mandatory flood insurance|
|AR Zone||Temporarily increase flood risk due to building or flood control restoration||Mandatory flood insurance|
|A99 Zone||1% chance of flooding & protected by federal flood control systems||N/A|
Moderate Flood Hazard Areas (MFHA)
|X Zone||Moderate risk of flooding||Insurance is not mandatory|
|B Zone||Moderate risk of flooding||Insurance is not mandatory|
Minimal Flood Hazard Areas
|X Zone||Minimal risk of flooding||Insurance is not mandatory|
|C Zone||Minimal risk of flooding||Insurance is not mandatory|
Undetermined Flood Hazard Areas (UFHA)
|D Zone||Risk of flooding is unknown||Insurance is not mandatory|
To learn if your block of land is impacted by these flood hazard areas, head to the FEMA flood map service center to enter your address.
It is also important to consider the depth of flooding common within the area along with the overall risk of flooding, as this will impact the regulations and building materials required to construct your new home.
Elevated House Plans For Flood Zones
After assessing the level of flooding risk and whether insurance is mandatory for your home build, it is important to consider how your home design will be impacted and the necessary features required to minimize property damage and mitigate against flooding.
The base flood elevation (BFE) level should be considered here. This refers to the height at which the floodwater would rise during a base flood (the flood with a 1% chance of occurring in any given year). As mentioned above, this should be detailed for Special Flood Hazard Areas (SFHA) by the FEMA flood maps for areas expected to have the most impact from flooding.
When building a new residential home in a flood-prone area, it is important to build above this base flood elevation line as this can reduce home flood insurance premiums and protect the home from damage.
You could also be eligible for the insurance premium to be waived to get the property removed from the flood floor plans if you can prove your property or home design is above the 100-year base flood elevation level. However, you will require a formal document from FEMA to do so. We recommend getting a land surveyor or civil engineer along with your home design consultant to work through the FEMA removal process on your behalf.
Home Building Considerations for Flood-Prone Areas
After considering structural elevation levels and flood zoning risk it is time to consider flood-safe building materials and design inclusions to ensure your home is built to stand the test of time. It is important to select home foundation types and building materials that withstand water damage or flowing water impacts.
Typically, for homes in flood-prone areas, the main home foundation types include slab-on-fill, perimeter walls, standing on piers, posts or columns and piles. However, the correct foundation type will depend on the state and city requirements for flood-prone foundations and flooding risk. When building your custom flood home design, be sure to speak with your builder about the correct solution for your future home.
Other building inclusions and home flood mitigation options include flood vents or foundation vents on lower levels of the home which ensure hydrostatic pressure does not build up to impact walls and home foundations. Another tactic includes placing service equipment and utilities above the base flood elevation level which can minimize the risk of water damage to these appliances causing damage to household members and the wider community if a flood were to occur.
These inclusions can be discussed with your home builder in the initial design and consulting phase to determine the relevancy and efficiency of these features in your new home.
Flood Zone House Designs
Once you have thought through these initial considerations and discussed them with your home builder, you should be able to mitigate flood risks and keep your home protected and prepared for flooding long into the future.
At G.J. Gardner Homes USA we offer a variety of homes for sale along with our classic home designs. We are also specialists in custom home designs, meaning we can tailor your home design to suit your personal preference and design choices (including flood protection).
If you’re looking to build in a flood-prone area but don’t know where to begin, contact our friendly team and enquire today to get started!