Grading, in terms of the ground around the home, is the slope of the ground/soil around the foundation/perimeter of the home. Proper grading (or correct grading) is positive or sloping away from the house. This is vital to ensure proper drainage of water away from the home’s foundation. Proper grading can prevent things like leaks, cracks in foundations, the rot of wooden structural members, and other major/costly foundation problems.
If I had to estimate I’d say maybe 1 in 40 houses I inspect have proper positive grading on all four sides of the home. Unfortunately, it’s not something homeowners pay attention to, or something builders pay attention to for that matter (I see it in new construction too :/). While looking at houses, or looking at your own house, squat down and take a look down each side of the house at the ground near the foundation. Is it visibly sloped away from the house? A properly graded yard is easily visible and the slope is easy to see. If it is flat or sloped towards the structure then corrections will need to be made. The soil around the home is recommended to slope away from the foundation with a 6-inch drop in elevation in the first 10 feet away from the structure (or 5% grade). Check out the illustration below to see what I mean when I’m talking about positively sloped grading:
But what happens when a slope can’t be achieved? I see a lot of yards that are completely flat, have the soil already to close to the siding, and, either because of a close neighboring house or not enough property to work with, can’t be sloped properly. When a situation like either of those occurs luckily there is a fix! Something called a swale can be used or extra ground drains. A swale is a valley-like intersection of two slopes in a piece of land. Check out the illustration below for a visual explanation:
I can’t stress enough how important it is that water be directed AWAY from the home and foundation. Most all foundation problems can be traced back to improper drainage around the house. If your house has proper grading (or you get the grading fixed) the gutter downspouts still need to extend a minimum of 5 feet past the foundation so water runoff from the roof can be diverted away too (the further away from the house they are extended the better, but make sure they are sloped properly and avoid uphill runs).
One last note, I never recommend adding more soil to build upgrading to slope away from the house. Most homes I inspect have the soil fairly close to the siding and sometimes over the top of the siding making the siding below grade. This is a big issue that also needs to be corrected as it’s one of the contributors to the wood rot of structural members. You should have 6-8 inches of exposed exterior foundation showing below the siding. This is especially important for homes with brick or stone veneer siding. Brick and stone veneer sided homes have (or should have) weep holes on the bottom level of brick just before the foundation. Weep holes are small drainage holes that allow for any moisture behind the brick/stone siding to escape by draining out the bottom row of siding. If these are covered or below the soil they could actually be letting water in behind the brick which can lead to moisture damage of wood members. Check out the illustrations below to see what I mean.
Look at this graphic closely. It illustrates what I mentioned before that soil contact can cause rot of wooden structural members. The soil in this graphic on the exterior of the house is actually higher than the wood floor joists, sill plate, and rim joist on the interior of the house. The joists and sill plate are structural members of the house and can be costly to repair or replace. When the siding gets to the same level or higher of those members it makes it easy for water to get in and cause leaks, rot, mold, and foundation problems.
That’s why it’s important to allow for 6-8 inches of clearance between the siding and grade
(ground/soil/yard). If your house already lacks that clearance and has negative grade then building the grade up higher to increase slope is not an option, removing grade is the only option at that point.
Grading can be corrected by most land movers or landscapers. I recommend researching a price quoting multiple companies. Look at their reviews and never go with the cheapest bid, they’re the cheapest for a reason. Changing the slope of your yard may seem like a daunting task, but it really isn’t! To grade your yard, just find your high spot and low spot, and reverse them. Not only is this a cheap and easy DIY project, but it’s a proactive one. Being a proactive homeowner is the ONLY way to be. Stopping drainage problems before they start will stop leaks before they start. This stops water damage before it starts. This stops you from having to open your wallet. Saves you huge headaches in the future.
source: by Zac https://rigidinspections.com/why-proper-grading-is-crucial-for-a-home/