How to Inspect Grading on a Home Inspection
Landscaping and grading is not just for a beautiful appearance around your home, but is also needed to keep basements and crawlspaces dry and prevent structural movement. There are several items to consider when discussing landscaping and grading but we will be looking at primarily the requirements and positive effects of grading.
By “Code” (yes that dirty 4 letter word for Home Inspectors) the grade should slope away from the home at a rate of 1” per foot for the first 5’-6’ or 6” in the first 10’. While we do not generally refer to code let’s look at the principle for proper grading. If we have a light rain, the soil soaks up the moisture and there is rarely an issue, but when we have a good downpour or even simply a steady rain when the ground is already saturated, the water is going to flow somewhere. A proper grade will allow the water to flow away from the home and foundation. A negative grade allows the moisture to flow back towards the home and seep into the soil. The more rain and the more saturated the soil is to begin with, the more of a pressure this moisture puts on the foundation forcing itself through the foundation and into the basement/ crawlspace. Drain tiles, damp proofing coatings, etc, will all help prevent to keep basements and crawlspaces dry, but the key is to keep the moisture away in the first place. Proper grading will accomplish that objective.
When Moisture does get into the basement/crawlspace, it can be a real nuisance. Damage can occur to storage, carpeting, and possible structural components. Home owners also hate the cleanup from excessive water. In a crawlspace Moisture can be very damaging. Rot and deterioration of floor joists, sill plates, box sills, rim joist, girders can all be can all be bi-products of improper grading and moisture penetration. While proper crawlspace venting help to eliminate high moisture content venting alone may not be enough if the moisture levels are too high. Making sure that you have a 6”-8” clearance from the soil to the siding and/or rim joist is also important to prevent structural damage. When the soil around your home is saturated a lateral pressure can also be applied to your foundation walls. This pressure can cause the walls to move and cause failure to the structural integrity of the foundation.
Grading is something that many home owners can overlook, take for granted or simply underestimate the importance. As a professional home inspector, never forget to make your clients aware. Always recommend that they take the necessary steps to ensure a positive grade away from the home.
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