Mitigation Strategies

While flood insurance will not keep your home or belongings from being damaged, it can help you recover at least some of the costs of damage. Renters can purchase flood insurance for their personal belongings, while homeowners should insure both the building and their belongings.

If your home is in danger of flooding, move electronics, important paperwork, and belongings that may be easily damaged or have sentimental value off the ground.

Figure. Single Sandbag Placement

Sandbags are an effective temporary way to reduce flood damage. They can keep floodwaters away from building openings (doors, windows), outside walls, or other vulnerable building components (e.g., outdoor HVAC units). When there is no strong current, waves, or danger from floating debris that could topple the bags, a single row is fine. If flooding involves waves, strong currents, or large debris, you may need to create a wall that is two rows wide. Here are the steps to mitigate flood with sandbags correctly:

• Make sure that the bag flap is folded under, facing away from potential floodwater. If using a tied bag, flare the tied end out.
• Place the bag lengthwise, parallel to the direction of the water flow.
• Tamp down on the top of the sandbags before placing the next row to help create a better seal.
• When stacking bags two or three layers high, make sure the top layer overlaps the bottom layer, similar to the process for laying bricks. Stacks that are more than three layers high (approximately 1 foot) may topple over, so you may want to add a second row of bags to make the stack wider.
• Make sure to add a waterproof layer between the sandbags and the building door. A waterproof plastic or canvas should work. Secure the layer by taping it to the door frame.

Estimated cost: The number of sandbags you need determines the cost. Your municipality may provide sandbags to residents for free (though you may have to fill them yourself). If you purchase a 40-bag pallet of sandbags from a home improvement store, cost is about $470 (from HomeDepot.com, 2021).

Sources

• Home Depot 40 Bag Sandbag Pallets
• BJ's Sandbags for Flooding and Protection
• Sandbag Calculator (How Many Sandbags Needed)

Figure. Flood elevation on pilings

One of the most effective ways to mitigate residential buildings against flooding is to raise the first-floor elevation of the buildings above the base flood elevation (BFE, the elevation level required by most building codes) or above the historical high water mark. In inland areas, you can increase the freeboard (feet above BFE) using pier and beams, slab on fill, or stem wall foundations. In coastal areas, buildings must be elevated using pilings.

Estimated cost: Elevating buildings during the construction process only increases the construction cost by a small percentage. For instance, 3 ft. elevation above BFE only increases the construction cost by about 3.56% ($8,000 for a single-family home with 1,500 sq. ft. floor area). However, elevating existing buildings is much more expensive. Cost depends on variables such as the level of elevation, foundation type, and number of stories. For more details on potential costs, contact a certified contractor.

Figure. Raise or floodproof HVAC equipment (FEMA 2008)

Heating, ventilation, and cooling (HVAC) equipment, such as a furnace or hot water heater, can be damaged extensively if it is inundated by flood waters. A good way to protect HVAC equipment is to move it from the basement or lower level of the structure to an upper floor or even to the attic. Another option is to construct a concrete floodwall around the HVAC components

Estimated cost: Having your furnace and hot water heater moved to a higher floor or to the attic will cost about $1,500. The cost of a floodwall will depend partly on its height and length. A 3-foot-high wall with a perimeter length of 35 feet would cost approximately $2,500 (based on a 2008 FEMA estimate).

Figure. Practices for building with flood damage resistant materials (FEMA 2008)

Constructing a building with materials that are more resistant to flood damage like polyester epoxy paint or decay resistant wood can provide some protection.

Figure. Wet floodproofing flood mitigation (FEMA 2008)

Wet floodproofing is a technique to allow flood waters easily enter and exit the enclosed areas of a house during flood events. Flood waters inside the house can rise and fall quickly at the same rate as flood waters outside. This decreases the effects of hydrostatic pressure, including buoyancy (when flood waters make a building float). As a result, the likelihood of structural damage may be greatly reduced. Wet floodproofing is generally used to limit damages to enclosures below elevated buildings, walkout-on-grade basements, below-grade basements, crawlspaces, or attached garages. It is not practical for areas that are to be used as living space. In wet floodproofing you need to make sure to:

• protect the areas of the house that are below the flood level from damage caused by contact with flood waters
• protect service equipment inside and outside the house
• relocate any materials stored below the Flood Protection Elevation (FPE)

Estimated cost: The cost can be obtained by contacting building contractors.

Figure. Sewer backflow valves (FEMA 2008)

In some flood-prone areas, flooding can cause sewage from sanitary sewer lines to back up through drain-pipes. A good way to protect your property from sewage backups is to install backflow valves, which are designed to block drain-pipes temporarily and prevent return flow.

Estimated cost: Having a plumber or contractor install one backflow valve will cost approximately $1,400 for a combined gate/flap valve or about $600 for a flap valve. These figures include the cost of excavation and backfilling (based on a 2008 FEMA estimate).

Figure. Raise electrical system components (FEMA 2008)

Electrical system components, including service panels (fuse and circuit breaker boxes), meters, switches, and outlets, are easily damaged by flood water. If they are inundated for even short periods, they will probably have to be replaced. Another serious problem is the potential for fires caused by short circuits in flooded systems. Raising electrical system components helps you avoid those problems.

Estimated cost: Raising the electrical service panel, meter, and all of the outlets, switches, and wiring in a 1,000-square-foot, single-floor structure will cost about $1,500 to $2,000. If this work is performed during the repair of a damaged structure or construction of a new structure, the cost may be much lower (based on a 2008 FEMA estimate).

If you have an external fuel tank, it can tip over or float away in a flood, causing fuel to spill or catch fire. Cleaning up a house that has been inundated with flood waters containing fuel oil can be extremely difficult and costly. Fuel tanks should be securely anchored to the ground. Make sure vents and fill-line openings are above projected flood levels. Propane tanks are the property of the propane company. You’ll need written permission to anchor them. Be sure all work conforms to state and local building codes.

Safely using and storing necessary flammable materials, including machine fuels. Approved safety cans should be used for storing gasoline, oily rags, and other flammable materials. Firewood should be stacked at least 100 feet away from homes.

Be sure your insurance covers wildfire.

The primary way to mitigate wildfire hazard is to create defensible space around a building that can slow the spread of wildfire. This includes the following tips:

• The distance from trees to the house should always be greater than the height of the full-grown tree, or at least 10 feet.
• The distance from an outbuilding or shed to the house should always be greater than the height of the outbuilding.
• Remove combustible materials, such as shrubs, brush, and woodpiles, out to a radius of 30 feet.
• Prune and clear dead vegetation and cut high grass all around your home.
• Increase the space between plants and trees. The spacing between grass, shrubs, and trees is crucial to reduce the spread of wildfires. The spacing needed is determined by the type and size of brush and trees, as well as the slope of the land.
• Remove all tree branches below 6 feet from the ground.

Estimated cost: If you hire a contractor to remove a large tree, you can expect to pay about $1,000 to $1,500. The charge for removing smaller trees and shrubs would be less (based on a 2008 FEMA estimate).

Choose fire-resistant plants and materials for landscaping.

Estimated cost: The cost can be varied based on the kind and number of plants.

Some roofing materials, including asphalt shingles and especially wood shakes, are less resistant to fire than others. You can replace your existing roofing materials with slate, terra cotta (clay), or other types of tile, or standing-seam metal roofing.

Estimated cost: If you hire a contractor to replace your existing roof covering, you can expect to pay about $4 per square foot of roof area for tile or metal roofing and about $7 per square foot of roof area for slate. For example, a structure measuring 60 feet by 30 feet will have about 1,800 square feet of roof area. For this structure, tile or metal roofing would cost approximately $7,200 and slate would cost approximately $12,600 (based on a 2008 FEMA estimate).

Use materials such as stone, brick, and stucco for new construction in wildfire hazard areas.

Estimated cost: The cost can be obtained by contacting the building contractors.

Purchase and install external, structure-specific water hydration systems (sprinklers); dedicated power sources; and dedicated cisterns if no water source (e.g., lake, river, or swimming pool) is available.

Staying away from windows can protect you from injury if hail breaks a window.

Roof sheathing, hail resistant roofing and siding, and impact resistant shingles can all help protect your home from hail damage. You can contact the Insurance Institute for Business and Home Safety (IBHS) to learn more about the most appropriate type of roof covering for your geographic region

Estimated cost: Costs can vary. For example, hail resistant shingles typically reduce a homeowner’s maintenance costs and cost 10-20% more than their non-impact counterparts.

Construction features such as structural bracing, shutters, laminated glass in window-panes, and hail-resistant roof coverings or flashing in building design can minimize damage from hail.

A frozen pipe can lead to pipe busting and it can cost homeowner more than $5,000 in water damage.

Estimated cost: Pipe insulation can cost as little as 50 cents per linear foot. You can check your local hardware store for a more accurate cost estimate (Based on IBHS estimates).