Home inspectors are frequently asked about flood plains. This is not part of an inspection, but here is the way we find out about flood plains in your area.
When hurricane season approaches, that our concerns turn towards flooding in Houston, and as a home inspector I am frequently asked about the flood plains. One of our worst floods in recent years came from a tropical storm, Alison, rather than a hurricane, but with such a flat area, any good rain can turn into a flood. Please be aware that much of the area in and around Houston can flood, depending upon what the storm does. I was told not too long ago that all of Houston is now considered to be in the 100 year flood plain.
Most people who are familiar with maps showing areas that flood use two general terms to refer to them: flood plain map; or a 100 year flood plain map, but you need to understand what they mean. The second name confuses many, because it seems to imply that floods occur every 100 years. This title indicates the time period over which an area is studied, not how often a flood may occur. When you are in an location that is said to flood every one hundred years by this map, it means that you have a 1% chance of having a flood each year. Another term to refer to these maps is FIRM. This heading is applied by FEMA, and it stands for Flood Insurance Rate Map. The last phrase which you may hear used is Special Flood Hazard Area (SFHA), which is used by municipal governments.
What I have noticed is the organization which oversees water distribution to your area(like the Water Department in the City of Houston) will be the authority to inform you about these maps. You do not have to wait for their reminder though to check your neighborhood. By going to FEMA’s website, you can locate the map that you need. All that is required is your street address and zip code. Once entered, you will be asked if you wish to purchase the map or view it. By viewing it, you are brought to a page with the detail of your area. By creating a FIRMette (which is a small detail map), you can have this map for your own computer. I noticed that with dial up, this takes a long time.
You may be surprised to find that a flood has occurred in your area. I remember the surprise of friends and acquaintances when they experienced flooding in El Paso. If you are curious, go to the link above to find what is happening on your street.
If you cannot wait for the flood plain map, here is some advice to consider if your home is susceptible to floods. Most of Houston sits on a flat coastal plain, and water needs a hill like surface to flow away from us. Since we do not have this hill like structure, we rely on our sewer systems and waterways. This is why are bayous are re-engineered to create a flow (like Brays Bayou). Does your driveway look like an incline, or is it just a little bump up with the lawn being flat? If you have an incline, there is less chance of water coming from the street. Do you live close to a bayou or creek or other form of waterway? Houston and Harris County have worked hard to create spillways which allow water to flow into these areas, creating temporary ponds, so that water does not easily flow over the banks of the waterway. However, the closer you live to bayous or creeks, the greater the possibility of flooding.
There is another factor concerning flooding in your home, where a home inspector can help you determine if you have to be worried. Part of the standard home inspection in Texas, an inspector will check the grading around your home. I have seen it on many occasions where water from the street was not the problem, but the landscape around the home caused flooding in the home. Here are some common problems that I find when inspecting a home:
Patios are poorly designed so water can flow back towards the house. If you notice spots on the wall that look wet or maybe have algae growth, water can be coming back to pond in that area.
The neighbor builds up their garden bed next to your home, but your landscape is lower. This allows water ponding, which is bad for your foundation, but I have seen water get so high that it flows into a home through a weephole in the brick and stucco exteriors. The best solution is that you and your neighbor install a drainage system down your property line to the street.
Poorly maintained or designed gutter systems. A clean gutter will take rain to a downspout, which then should force the water away from the home. If the gutters are not doing this, water will have to find its own way from the building, but it may just find a low spot, and stay there.
The level of the ground forces water towards the home. Now, if you are living on a hillside, you cannot do much about this factor, but Houston is flat. Builders grade the lawn areas towards the end of construction, when they know no other equipment will be driving over that area. Generally they are good about grading properly, but I have seen cases where this is not always done correctly. Over time, homeowners add and remove garden beds, which changes the grading around the home. This practice may have inadvertently caused the grading to force water towards the house.
Not all damage from rain is from flooding, and a home inspector should point out problem areas in your walls and roof. When I was inspecting a home after Hurricane Ike, the buyer thought that there had been flood damage to the home, because he saw a water stains on the walls. I pointed out that water is flying every which way during a storm. When looking at the corners of the building, I saw that there were gaps which needed to be caulked that allowed water to come into the structure.
If you have any questions, you can go to the request a quote page for a way to ask questions, or if you have your own home inspector, you can ask them about these concerns.