Just because your basement is flooding, doesn't necessarily mean that there is a leak, water rises around your basement and can cause basement flooding too. Whatever the cause of the flooding is, nobody wants to spend thousands of dollars on repairs that could have been easily remedied or mostly prevented if they were caught early. There are a couple of facts to know about heavy rains before discussing how they affect your basement.
- Heavy rains cause your home's eavestroughs to spill over and your downspouts to discharge what could potentially be hundreds of gallons of water in a short amount of time.
- It can flood your backyard and cause large amounts of hydrostatic pressure against your foundation walls, as well as cause the water table to rise.
- It can also overload the storm sewer system on your street and cause the floor drain in your home's basement to back up.
High Water Tables
Some areas have high water tables that cause huge headaches for homeowners. For those who need a little middle school science memory jog, a water table sits underground and is the level at which soil and gravel are completely saturated with water. There is usually seasonal change in the water table, due to rain or drought. High water tables are particularly common in areas where the soil does not drain well because the ground contains high levels of clay.
The level of the water table varies greatly depending on the amount of rainfall, time of year, and the type of soil that the surface water drains through. The denser the soil, the slower the movement of the water through the soil. This is called percolation.
How This Affects Your Basement: When water tables take in more water than they can drain off they become elevated. High water tables are often above the level of basement floors or crawlspaces. This almost always causes flooding.
Eavestrough & Downspout Overflow
When an eavestrough overflows, instead of draining through the downspout the water saturates the soil around the foundation. Downspouts introduce much more hydrostatic pressure against a home's foundation than eavestrough. In these sorts of situations, the level of the water table next to the foundation walls will rise, which results in increased hydrostatic pressure. The water pour-over will not be an issue if your home's basement is waterproofed. If the foundation walls are properly waterproofed, no water will enter the basement and there will be no issues with flooding.
Storm Sewer & Floor Drain Backup
During extreme rains, the storm sewers beneath the street can get overloaded and become incapable of holding all of the water entering in. These conditions are most notable when trying to drive home in flooded streets but, the storm sewers want to naturally relieve pressure the easiest way possible -- and that could easily be your basement. Many flooded basements are caused by water backup in the floor drains.
- One way to prevent basement flooding due to water buildup is to waterproof your basement with a basement wall vapor barrier.
- Downspout issues can be helped with extensions, that guide water away from your home's foundation.
- To fix backup from floor drains, there is a great combination of installing a sump pump and an interior perimeter drain. This will direct the water out through the sump pump and away from the foundation.