Factors to Consider When Flood-Proofing Your Home

Flood-proofing requires that home owners, builders, architects, engineers and planners, engage in detailed assessment of the feasibility of building in high-risk flood-prone areas.

Consider the following factors before attempting to flood-proof your home:

Flood Characteristics

  • Height of maximum flood level: the lower the depth of floodwaters, the easier it is to flood-proof a building or other structure.
  • Velocity of water flow during flood peaks: the lower the flow velocity, the easier it is to design a building resist floodwaters.
  • Duration and frequency of floods: the susceptibility to flooding of a given area makes flood-proofing more difficult and expensive.

Structural Factors

  • When floodwaters surround a building they impose uplift (vertical) and lateral (horizontal) loads on the structure and sub-structure. The pressures exerted by these loads must be pre-determined in order to design adequate flood-proofing.
  • Residential buildings often require special design modifications because they usually have neither the necessary anchorage nor the strength to resist lateral forces.
  • Uplift and lateral forces against a foundation slab and walls, caused by the infiltration of floodwaters through the foundation backfill, are especially significant in building design and construction.

Economic Factors

  • The decision to use flood-proofing techniques alone, or in combination with flood protection works such as dykes, requires a cost-benefit analysis.
  • If you are seriously considering adapting any flood damage reduction methods, obtain the services of a qualified professional engineer to help you select and design the right measure tailored to your particular needs.
  • This is especially important if your house or light-framed structure is, or will be located in an area susceptible to fast-moving flood waters, or the cost involved is substantial.
  • Remember, flood-proofing measures will not necessarily eliminate the risk of your house ever being flooded. If anticipated benefits exceed the estimated cost then flood-proofing will be economically justified.
  • Costs will vary considerably, however, depending on local flood characteristics, viz. the type of size of structure; the financial terms of capital to be invested; and the elevation to which the building must be protected, say for insurance purposes. Benefits, therefore, depend on the estimated flood damage that flood-proofing will prevent.