Does the Ground Slope Away From Your House? A Grading Check Before the Freeze

A lot of wet basements and cracked foundations don't start with the foundation at all. They start with the dirt around it. If the ground slopes toward the house, every rain and every spring thaw runs straight at your basement walls. Fixing it is often a few bags of dirt and a Saturday.

01What it should look like

Most building codes, including the International Residential Code, call for the ground to drop at least 6 inches in the first 10 feet away from the foundation. Driveways, sidewalks and patios next to the house should slope away too, at least a little (about a quarter inch per foot).

Over time, that slope disappears. Soil settles next to the foundation, especially where it was backfilled when the house was built. Mulch, flower beds and landscaping edging get added. Before long, the low spot is right against the wall.

02How to check it

Walk around in the rain. The easiest test. Watch where water goes and where it puddles. Water that pools or runs toward the house is your answer.

The string test: 1. Drive one stake against the foundation and another 10 feet straight out. 2. Tie a string between them and use a line level to make the string level. 3. Measure from the string down to the ground at the outer stake. You want 6 inches or more.

Do this on every side of the house, and anywhere you see a low spot.

03Other things to look for

• Soil or mulch piled above the foundation and touching the siding. You should see several inches of foundation between the ground and the siding. Soil against siding invites rot and termites.
• Sunken patios, walkways or stoops that tip toward the house.
• Downspouts dumping right at the foundation. See our guide to gutters and downspouts.
• Window wells that fill up with water.
• Low spots where snow piles up against the house and melts in spring.

04Simple fixes

• Add soil. Use a clay-rich fill dirt (not topsoil or mulch, which soak up water) against the foundation, and slope it away. Tamp it as you go. Topsoil and grass or mulch can go on top.
• Keep the foundation visible. Don't bury the siding.
• Extend the downspouts several feet out, or into a buried drain line.
• Raise or replace a sunken stoop or patio, or have a concrete contractor mudjack or foam-lift it.
• Add a swale (a shallow, wide ditch) if your yard has a hill sending water toward the house.

05Before the freeze

Get it done before the ground freezes. Wet soil against a foundation freezes, expands and pushes on the wall, and that's how small cracks get bigger. And whatever doesn't drain in the fall comes back as snowmelt in the spring.

If you already see water in the basement, cracks that are growing, or a sump pump that runs constantly, fix the grading and also read our guides to foundation cracks and testing your sump pump.

Sources (2)

InterNACHI: Inspecting Load Paths and Water Paths (IRC R401.2 & R401.3) · InterNACHI Inspection Gallery: Slope of Grade

Related: Inspect Your Roof From the Ground: What Binoculars and the Attic Tell You