The Types of Flooding and How to Protect Your Home
Over the last 100 years, flooding has claimed millions of lives the world over. No location is truly safe from flooding as the cause of flooding is varied. A flood can materialize after hour or days of excessive rain. In cases where flood develops under six hours of rain, then that is what is known as flash flood. There are four basic types of flooding: river flooding; coastal flooding; urban flooding and flash flooding.
- River flooding - The flooding of rivers is as predictable as the rising and setting of the sun. They could occur due to the winter or spring rains that come with the melting snow. The river is filled with excessive water that it can't readily displace in a bigger body of water. Typhoon or hurricane rains could also flood the river and its supporting systems of smaller bodies of water.
- Urban flooding - Concrete roads and streets are impermeable materials. They cannot absorb rain water. There are storm drains that are built as the exit points of roadways surface water but at times, there's just too much water volume and the storm drains cannot handle such. It may also be that the storm drains are clogged with debris or the mouth of the storm drain that opens up in a body of water is blocked by debris tool. In cases of urban flooding, the streets can be transformed into swift moving rivers. House basements and ground floors can turn into veritable traps.
- Coastal Flooding - Coastal flooding can occur during typhoons and hurricanes. Sea water is driven inland by the wind. This could be further aggravated by the tides. Coastal flooding could also be an offshoot of tidal waves and tsunamis that are caused by earthquakes.
- Flash flooding - This could be attributed to several factors: intensity of the rain, condition of the storm drain, condition of the river and nearby bodies of water, the soil condition and topography. There have been cases of flash flooding due to the breakdown of dams or its inevitable release of water.
There are three ways that your house can be "flooded". Water can enter your house through any of the four types of flooding, by sewer backup and by water seepage from the ground.
It seems like there are ways to escape flooding. If you don't want to experience river flooding, don't live near any river. If you don't want to be a victim of coastal flooding, move out of from that coastal home. If you don't want to experience catastrophic flooding in terms of dams and water reservoirs breaking, make sure your house is out of a dam's water release path. Easy enough. However, what do you do in case of urban flooding? Or if the sewer backs up or if groundwater seeps into the basement? You might just have to flood-proof your home.
Flood-proof Your Home before It is Built
The rule of thumb when considering the elevation or height of the ground floor from the main street to which the structure faces is to elevate the ground floor at least one metre from the centre of the street. The one metre difference would give you ample height in case of flooding. Currently a two metre difference from the centre of the street to the structure's ground level is better.
If you have a basement in the house, make sure that the walls are plastered with mortar that has a waterproofing additive. The waterproof additive or vapour barrier would slow down if not totally stop moisture from seeping in. It is best to elevate your basement from the street level by at least 600 mm.
Build the ground around the foundation sloping out of the house. Ideally a slope of one inch per foot for the first six feet will do. You can also install a false floor over the basement floor to allow water to flow to a sump pump. An interior or exterior drainage system is highly recommended for homes located in flood-prone area. Remember to have a qualified plumber install a backflow valve to keep water from backing up through the drain.
If your house is likely to be flooded it is best to locate electrical panel way out of the anticipated flood level. If it's allowable, better install the electrical panel on the upper floor. Make sure the heating ducts are insulated and watertight.
There's only so much that you can do. However, the above pre-construction suggestions will help to an extent, flood-proof your home.
Flood proofing for already Built Homes
If your area is prone to flooding, relocate the electrical panel above the anticipated flood line. If flooding is only from 3 to 4 inches, install a float plug in the drain. This will not work for deeper water in the basement though. Some other measures that you can do are:
- Elevate on at least 12 inches platforms heating and hot water systems, washers, dryers and all other appliances in the basement.
- Don't store anything that is highly valuable or irreplaceable in the basement
- If downspouts are connected to the sewer or storm drain system, disconnect them so as to reduce the flow of water into the community sewage system. Make sure the downspouts are at least 1.50 metres away from the house's foundation.
- Have a qualified contractor add waterproof veneer on the exterior wall. This would only work for flood water that is up to two feet. It will not work on higher level of flood water because the pressure of the flood water would most likely be greater than the wall's strength.
- Get a flood insurance. Most flood insurance companies will apply the 100-year-flood equation.
- Follow emergency and safety measures and precautions in case of flooding.