Proper Lot Grading Around House
The Importance of Maintaining Proper Grading Around the Foundation of Your Home
As a result of (common) backfilling practices that most home builders incorporate, the lot grading around the perimeter of the concrete foundation (Grading Around House) will settle (sink) over time. This is one of the reasons why we (as a landscaping contractor) are unable to provide any warranties with Patios or Sidewalks that are built in close proximity to the foundation walls. Read on for more information about grading problems (grading yard for drainage) and how our yard grading services can help!
Here is one example of a client that was experiencing consistent water problems in their basement:
They purchased a $1.2 Million Dollar home in Edmonton that was only 4 years old. In the space of just “one” year, their basement had flooded “four” times. They contracted us to assess and rectify the problem. The first thing we did (and always do) was to “survey” the lot in order to verify where potential grading deficiencies existed. After we did this we came to the conclusion that they were experiencing problems with water entering their basement for “two” primary reasons. 1. Their neighbour’s sump pump discharge hose was directing water onto their property. 2. A “Builder Installed Window Well” had not been installed correctly and surface runoff water was finding its way underneath the Window Well. During heavy rainfall the ground around this particular area of the home would become “Super Saturated”. As a result, the ground could not absorb any more moisture, so the water level would rise and it would find its way through the sliding window and into the basement. We rectified the “Grading” and “Window Well” deficiencies… and their basement has been dry ever since!
Common Drainage Problems Associated with Newly Built Homes
The reason the ground around the perimeter of the foundation is subject to settling (sinking), is very “little” or “zero” effort is applied to ensuring the backfill material is compacted when it is used to fill the cavity that was created in order to construct the foundation. Instead, most home builders elect to hire “Mother Nature” and let her take care of this process for them.
Why do they do poor grading around house?
Because it’s “cheaper” and it “saves time”. It’s really that simple! The problem with this practice… it’s a slow process and is only accelerated with the aid of moisture that is introduced into the ground by rainfall and the melting of snow and ice in the spring.
Depending on the time of year the backfilling is performed, the ground around the perimeter and close to the foundation may be subject to even more “severe” settling. This is more evident when the backfilling is completed during “sub-zero” temperatures.
Why is temperature important to lot grading?
When the foundation is excavated the native soil (clay) is typically moist or even wet. It is piled and stored above grade until such time the basement walls have been poured and the forms have been removed. After the concrete has had sufficient time to cure, the backfill material that was stored above ground is used to fill the cavity between the basement wall and the undisturbed ground. The problem with this practice and especially during the winter months, is the (moist and wet) material that was excavated and stored above ground a number of weeks ago, has frozen! The practice of utilizing “frozen” backfill material creates even more problems with future settling, as it has numerous “annular spaces” and “air pockets” in-between the frozen lumps of clay. When the frozen material eventually (and it will take some time) thaws, it compresses together, resulting in the settling (sinking) of the ground above. As a result of the “settling” of the soil, it will start to create a “negative” grade situation.
What do we mean by negative grade?
Instead of surface runoff water being driven “away” from the foundation, it will now be driven “towards” the foundation. On newer built homes, the water will find its way down to the “Weeping Tile System” and into the “Sump”. When the water level rises to a pre-set level in the sump, the pump kicks in and water is pumped out. If the sump pump hose is long enough and positioned correctly, the water will flow away from the property and into the storm water sewer system as intended. If the discharge hose is not long enough or positioned incorrectly, the water has the potential to flow back towards the foundation and into the Weeping Tile System… and the process is repeated all over again.
If the grading around the perimeter of the foundation is not rectified, the foundation of the house will continue to be subject to the build-up of excessive amounts of moisture. This typically occurs and is further “compounded” after the thawing of snow and ice and after heavy and prolonged periods of rain in the spring. The (dry) ground acts like a sponge and has the capability to absorb a certain amount of moisture, but if the ground becomes too wet it becomes “Super Saturated”. When this occurs the excessive moisture will start to have a “negative” effect on the foundation and walls. The build-up of excessive amounts of moisture will start to impose “Hydraulic Pressure” on the foundation walls. This process will compromise the concrete and may eventually lead to water entering the basement.
Excessive amounts of moisture in and around the perimeter of the foundation can also create other problems. As winter sets in the moisture freezes and turns to ice. As a result, this will impose additional (external) pressure on the foundation walls. As a result of the external pressure being applied to the concrete, (small) cracks will form. Moisture will enter these cracks during “Thawing” cycles and “Re-Freeze” when temperatures drop below zero. When this happens the concrete is further “compromised” as a result of the expansion of the cracks. This is not something that happens overnight, but if it is not rectified it will eventually lead to the (concrete) foundation being compromised and the potential for water to find its way into the basement.
Conclusion on lot grading:
If grading issues are addressed and addressed relatively quickly, you can avoid the risk of incurring water damage to your basement and the costs and inconveniences that go along with it.
I hope you found this article to be both educational and informative!