Though very common, flooding is one of the most expensive weather disasters experienced in the U.S., as reported by the National Oceanic and Atmospheric Administration (NOAA). It costs American citizens over $260 billion from 1980 to 2013, and this figure does not include the effect of hurricanes Andrea, Barry, Chantal, Humberto, Erin, Gabrielle, and Dorian in 2019.
It is complicated if not impossible, to entirely flood-proof a home, but there are many steps you can take to reduce the effects of flood damage. Maybe you are doing repairs after a recent flood or moving into a flood-proof area and want to ensure your refurbish project uses the most up-to-date measures. Here are some great ideas to get you started.
What is Flood-Proofing?
Flood-proofing is any measure (whether structural or nonstructural) intended to prevent the damaging effects of flooding to a building. It requires that homeowners, builders, architects, engineers, and planners, take a detailed assessment of the viability of erecting a building in high-risk flood-prone areas.
Apart from structural measures, flood-proofing also takes into consideration the preparation of plans to implement standby or emergency measures in anticipation of a flood, such as sandbagging, moving furniture and valuables to high floors, blocking openings or safely evacuating the premises, and others.
Flood-proofing is not a complete solution to every flood issues. It is rather one of the many available flood damage reduction options.
Factors to Consider When Building a Flood-Proof House
You need to consider the following factors before attempting to flood-proof your home as they are essential and can either mar or complement your efforts towards flood control:
Flood characteristics consider the following:
Height of optimum flood level – It is more natural to flood-proof a building or other structures when the depth of floodwaters is lower.
The velocity of water flow during flood peaks – Lower flow velocity makes it easier to design a building that resists floodwaters.
Frequency of floods and its duration – The susceptibility to flooding of a given area makes flood-proofing more painful and expensive.
When floodwaters surround a building, they impose both uplift (vertical) and lateral (horizontal) loads on the structure and sub-structure. The pressures exerted by these loads must be determined beforehand to design adequate flood-proofing.
Most buildings, especially the industrial and commercial ones, have enough support and connections and are big enough to withstand lateral forces produced by floodwaters. In the other hand, residential homes usually require specific design changes as they do not have the necessary anchorage nor the strength in most cases to resist lateral forces.
Vertical and horizontal forces acting against a foundation slab and walls, which are caused by the infiltration of floodwaters through the foundation backfill, are especially important in building construction.
If you decide to use flood-proofing techniques alone, or together with flood protection works such as dikes, you need a cost-benefit analysis.
But, if you decide to use any flood damage reduction techniques, then look for a qualified building engineer to help you choose and design the right measure tailored to your particular needs.
Toeing this line is especially important if your house or light-framed structure is, or will be located in an area prone to fast-moving flood waters, or the cost involved is high.
It is worthy to note that flood-proofing measures will not indeed remove the risk of flooding in your house. If the benefits you are expecting surpass the estimated cost, then flood-proofing will be justified economically.
The costs of flood-proofing a building will vary significantly based on local flood characteristics such as the type of size of the structure; the financial terms of capital to be invested; and the elevation to which the building must be protected. But, the benefits are dependent on the estimated flood damage that flood-proofing will prevent.
Ways to Build a Flood-Proof Home
There are many ways to construct flood-proof home and each method has its uniqueness. Take a look at each of these methods.
Dry water or flood-proofing method
If you are going to allow the flood waters to advance to the walls of your home, you might want to make them watertight. You can do this with sealant, or building in a waterproof membrane. Also, you will need to flood-proof the doors and windows as well as raise or seal the airbricks and utilities entry points. Therefore, dry waterproofing method ensures that all the water is kept out of the building.
Using Floating homes
Ideally, a floating house will always be above the water level. One of the ways to make your home float on water is to build it on boats and have a building that is always floating. But you need to consult with an expert home builder to guide you on how to construct a floating home in a flood sensitive area.
The elevation is the oldest and most common way to build a flood-proof home. If it is imperative to develop your home very close to a river or the sea, then make sure you lift it far above the height of the flood waters. There are several ways of doing that.
The traditional method obtainable in most places is to build a house on stilts. You can make it on a raised platform such as a beach house, or a bank of earth or concrete. An example might be putting a sacrificial car park underneath a big office building.
Wet flood-proofing method
An alternative approach to keeping water out of a building is to allow the water in but reduce the damage it can cause. How? By fitting a solid floor instead of wood, moving the power outlets higher the wall, and making sure that any fixed furniture is made of a material that can soak water at ease.
Wet flood-proofing is usually applied to retrofit flood-prone properties that the owners cannot sell. Retrofit flood-susceptible homes are designed in such a way that its lower floor has a swimming pool and non-essential services so that the whole property can flood without preventing patient care.
Flood walls method
Instead of raising your home above the water levels, another popular and effective technique is to protect your home or property from the water by constructing a robust and waterproof wall. This construction can be done to protect the whole towns and villages, as well as individual homes.
Constructing perimeter walls with watertight entrances are one method. You can also incorporate walls into the landscaping, to keep the water out of a whole building or allow the garden to flood while giving the house protection.
Most of these methods are well established as some of them have been used for many years in the past by riverine or coastal communities. As the weather becomes more hostile, more houses will be at risk of flooding and these techniques will become more critical and beneficial.