Foundation slope: the ground should slope away from the house at least 6 inches over 10 feet
PolyMagic has launched an extension of their business to include foundation repairs and soil grading. The service is available for both residential and commercial customers. The need for foundation repair can reduce the long-term costs and damage that could result if the area is not repaired properly.
Estimates are available free of cost, and can be requested online here or by calling our office at 816-765-4800.
According to the EPA, patio slabs, walks and driveways need a minimum slope of 1/4 inch per foot away from the house with back-fill to prevent settling. The final grade must be sloped away from the foundation by 1/2 inch per foot over a minimum distance of 10 feet. Keeping the proper slope allows water to drain away from the house foundation.
The consensus seems to be that a good slope to aim for when grading land extending out from a house foundation is about 6 inches for the first 10 feet (that translates to a “slope” of 5 percent).
The EPA presents two ways foundations are compromised by poor drainage. These include “surface water from rain and snow that drains from the yard toward the foundation because of incorrect grading” and “water that drains from the roof and is deposited next to the home’s foundation instead of being carried away.”
The International Residential Code or IRC does require drainage “around all concrete or masonry foundations that retain earth and enclose habitable or usable spaces below grade.” This includes your crawlspace or basement. Well-draining soils may be the exception. However, if your area has expansive clay soil, proper foundation drainage is essential.
Checking the Slope.
The first step in correcting foundation drainage issues is to determine if the soil around your home has the proper slope. Fortunately this is fairly easy to check. Obtain a nice straight 2×4 that is 10 feet long and a carpenters level. The ground should slope away from the house at least 6 inches over 10 feet.
Check the ground slope all around home about every 3 feet.
Some areas with insufficient slope can be corrected by moving soil from the areas 8 to 12 feet from your home back towards the foundation wall and smoothing it out to the proper slope. In other cases soil may need to be imported to the yard.
If your yard is very flat and the foundation wall is not tall enough to allow soil to be added, you may want to explore adding an underground slope, which could be done with a French drain.
If you have too much roof area draining through a single downspout, or two downspouts very close together, you will want to consider altering your gutter and downspout arrangement by adding more downspouts, or rearranging the ones you have.
Once the downspout drains onto the ground it is best to move that water at least 3′ away from the house as quickly as possible. See the pictures below or to the right for some ideas of how to accomplish this.
If you connect to your downspout to your French drain be sure to use leaf separators (see diagram) to keep leaves and twigs from clogging your French drain.
Another option is to use a rain barrel to collect the surge of water when it rains and then slowly drain the barrel over the next day by having it hooked to a hose leading to a garden or flowerbed. The hose should have an inexpensive ball valve at the end that is opened enough to allow a steady trickle of water. Open the valve fully occasionally when the rain barrel is full to clean out the hose and valve. Be sure to install an overflow pipe on your rain barrel for those very rainy days. The fact that the barrel self-drains each time prevents mosquito problems.