With the extreme amount of rain in the last few months in the Metro Area, houses are certainly feeling the effects. We, at FRED, are often asked by homeowners “What can be done to help this situation?”. Before I offer some suggestions, I thought it might make sense to explain exactly what is occurring. The ground water table exists naturally everywhere. As the rain saturates the soil, the ground table rises. As the ground table rises, this creates pressure not only on the foundations walls of a house, but also under the basement floor. This is referred to as hydrostatic pressure. Think of pushing a bowl down into an aquarium filled with water almost to the top of the bowl. Once you let go of the bowl, it pops straight up from the hydrostatic pressure of the water in the aquarium. Hydrostatic pressure, over time, works on the exterior face of foundation walls. Water is the most powerful natural solvent on the planet. Leaks will occur in foundation walls if this pressure is not dealt with.
There are some aggressive methods of handling this pressure, if the situation requires it. Excavating the foundation and waterproofing the foundation will prevent the wall from leaking. This alone, may not be enough. Installing drain tile below the footing level and adding gravel, before back-filling, will allow a chance for the pressure to be relieved, to a degree, because an area of least resistance has been created giving the water somewhere to go. In some cases, installing interior drain tile will be effective in relieving the pressure by managing where the water does. In this scenario, the ground water is actually let into the interior drain tile system and run into a sump pump. The water is pumped out of the house and the pressure is relieved.
There are, however, other things that can be done to help the house and foundation handle the high volume of ground water. Adding extensions to the downspouts is one way to force the direct rainfall out and away from the foundation. The farther away from the foundation the better. Making sure that the gutters and downspouts are clear and secured properly to the house will also help. Clogged gutters and downspouts cause additional water to fall close the foundation and therefore increase the amount of water right up against the foundation. Also, creating a positive slope in the grade of the yard away from the foundation will also help direct rain from entering the ground table farther away from the foundation. Negative slope (toward the foundation), will result in surface water being pushed at the foundation instead of away from the foundation. At least 65% of the issues with the ground table and foundations can be resolved by extending downspouts, making sure there is positive slope in the grade away from the house, and by making sure that the gutters and downspouts are clear and in working order.