What is Grading?
We home inspectors tend to talk a lot about grading around the house, and its implications. What is grading? Well, we aren't taking about red pens and gold stars. Simply put, the grade or grading around your house is the level of the ground. The ground level and how it’s graded is the deciding factor of where storm water will flow.
Positive and Negative Grading
There are two types of grading: positive and negative. Positive grading is good, negative grading is bad. Positive grading slopes away from your home, directing storm water away from your foundation. Negative grading slopes toward your home, directing storm water toward your foundation. When storm water consistently collects near the home only bad things can happen. That is why we tell our customers and document that negative grading needs to be corrected.
How do you know if you have positive or negative grading?
First of all, individuals who are buying a home should have a home inspection prior to purchase. Checking for grading issues will be one of the things your inspector will do. He will look for visual signs of negative grading. It's important to be informed though, because if the ground is extremely dry, the evaluation on inspection day may not reveal all conditions. Upon moving in and as part of regular home maintenance, homeowners should review gutters, downspouts and grading after heavy rains. This is the perfect time to notice where storm water flows. If water is collecting near the home, then the grading should be corrected. Note: Most new home owners will make changes to landscaping once they move in, like putting in flower beds, or walkways and other aesthetic changes. Just be sure to always be thinking about grade and how you may be effecting how water flows around your home as you make changes. It's so important that every homeowner takes the time to watch and see where the water goes. (We have some great tips on how to Watch and Learn from the rain here).
Can I fix negative grading?
Negative grading can be repaired, fairly cheaply. It can be as simple as shoveling soil toward your house. Or bringing in soil from another part of your property. Be careful not to cover your existing siding, this condition brings up a number of problems, like inviting termites for dinner, to name one. If you must add soil from an exterior source, use top soil (sometimes referred to as "blackdirt") or grading soil. These soils will keep much of the water at grade level until it has a chance to move away (or toward) your house. Do not use sand, because water flows through sand very easily and can turn a bad situation worse. In order to divert water away from the walls of the house, the soil must be dense and must slope away from the house.
Grading and Water Penetration
Did you know that well over 95% of water penetration problems into below grade areas of homes are due to surface water that is not managed properly? When grade slopes toward the walls of a home it allows water to accumulate at the walls. The worst areas are typically at downspouts, window wells, and adjacent to exterior steps. Also, the gutter and downspout systems contribute to water accumulation problems.