Site grading is an important issue that directly effects the home in many ways. Negative slope can impact the basement, wall cladding material, and even the safe passage to and from the home in some instances. There are many issues that can be caused by improper site grading.
The ideal slope at the perimeter of the home should slope positive (away from the home) approximately 1 inch in the first six feet. A slight slope is all that is necessary to divert water away from the foundation. Often times I find a negative slope (toward the foundation), this can cause water to pool near the foundation wall and promotes foundation wall seepage. The two biggest factors in avoiding foundation wall leakage is site grading and proper control of roof runoff. As a general rule the roof drainage system should deposit water runoff a minimum of 6 feet away from the foundation wall.
When I inspect the foundation wall I often find staining and almost always it’s in an area directly beneath improper slope, a disconnected downspout leader or at a window well location.
It is important to maintain a minimum distance to grade of your wall covering as well. A minimum of 8 inches is recommended for most siding materials, although 6 inches is acceptable foe many cement base products. Maintaining this distance is a great way to prevent siding damage as well as reduce the potential for insect and rodent infestation. Also when grade is in contact with the siding an easy path for termite entry is created. Keeping your basement dry is another way to prevent termite activity. Most insects like cool, damp areas so keeping these areas dry is one form of defense.
To summarize this short post, every spring take a walk around your home to see if you have any negative slope or possible settlement happening near your foundation. Re-grading these areas will help keep your basement dry. Also make sure your downspouts are not depositing water runoff near the foundation wall.
I hope this post was informative. As always, if you have any home related questions, please send them to me via the email address below. I will always help as much as I can.
Aaron M. Zuehlke is the owner and inspector at Zuehlke Inspection Service, LLC, a full-service home inspection company serving Southern Wisconsin. Specializing in Home inspection, Radon Testing, Mold Testing/inspection and Residential Thermal Imaging. He also manages several rental properties through Zuehlke Properties, LLC. He can be reached by email at Aaron@Zuehlkeinspections.com or by calling the office at 608-931-7485.