Yard grading: how to slope the ground away from your foundation

Where I look first

When a house has water in the basement or crawl space, I start outside before I look at any waterproofing system. My usual order:

1. Gutters
2. Downspouts and where they let the water out
3. The grade in the first few feet around the house
4. Window wells and basement entrances
5. Patios, sidewalks and driveways
6. Low spots next to the foundation
7. Swales and the way water moves across the whole lot
8. Buried drainage, and where it goes

I also step back and look from farther away. Sometimes the problem isn’t in the first ten feet at all: the whole backyard slopes toward the house.

How to check your yard grading

You need two stakes, string, and a line level or a long level.

1. Drive one stake near the foundation.
2. Drive the other about 10 feet out.
3. Tie the string between them and level it.
4. Measure from the string down to the ground at each stake.

The difference tells you how much the ground drops. Virginia’s residential code (R401.3, as amended in Virginia) asks for at least 6 inches of fall within the first 10 feet from the foundation. Where lot lines, walls, slopes or other barriers make that impossible, it requires drains or swales to carry the water away, and impervious surfaces within those 10 feet, like patios and walks, must slope at least 1% away from the building. That’s code for the situations it covers, not my personal rule. Other states and localities can set different requirements.

For an existing house, I don’t say, “You have 5 inches, so it’s wrong.” What matters is that the water actually moves away from the house and doesn’t collect in a low spot against the wall.

Signs of a grading problem

What I see most often:

• a low spot right next to the foundation;
• mulch piled up against the siding;
• soil that’s too high on the wall;
• a patio sloping toward the house;
• a sidewalk that forms a trough;
• gutters overflowing;
• erosion under a downspout;
• puddles next to basement windows;
• soil that has settled over the old foundation excavation.

That last one is very common. The soil that was backfilled around the house when it was built can settle over the years until it slopes the opposite way from how it started.

Fixes, from cheapest to most involved

1. Clean the gutters.
2. Extend the downspouts. See downspout drainage.
3. Fill small low spots.
4. Regrade a larger area.
5. Build a swale.
6. Install a surface drain, curtain drain or French drain.
7. Add a sump pump or interior drainage, if there’s groundwater that can’t be controlled outside.

I don’t go through those steps in order no matter what. If groundwater is coming up under a basement slab, I’m not going to spend months moving two inches of topsoil and hoping it goes away. And if a downspout is emptying right against the house, I don’t start by digging a French drain.

Drainage swales

I use a swale when I need to carry surface water around a house instead of letting it run toward it. A good swale has:

• a clear entry point;
• a continuous fall;
• enough width to move water without eroding;
• grass or other protection against erosion;
• a safe place to end.

A swale usually works better wide and fairly gentle than as a small, deep ditch. The classic mistake is solving your water problem by sending it to your neighbor. I also see swales with a low spot in the middle. At that point it isn’t a swale anymore; it’s a pond.

Regrading: DIY or call a pro

A homeowner can usually fix a small low spot without much trouble. I want fill that can be compacted, not a thick layer of mulch or just loose topsoil. I place the fill in layers and compact each one, and topsoil can go on top to finish.

What I don’t want to see:

• siding buried under soil;
• soil brought too close to the wood framing;
• brick weep holes covered;
• crawl space vents covered, if they’re still needed;
• basement windows buried;
• the termite inspection area blocked. Inside an unvented crawl space, Virginia’s residential code (R408.3.1) requires the vertical face of the sill plate to stay clear, with an inspection gap of 1 to 2 inches below it along the top of any interior foundation wall covering. The exceptions are areas not subject to termite damage and houses with another approved way to inspect.

For large jobs, steep or difficult slopes, or work that needs machinery next to the foundation, I’d rather bring in a grading contractor. Before anyone digs, Virginia requires a call to 811, homeowners included (more in French drains).

As a national reference, HomeGuide lists $500 to $1,000 to regrade along one side of a foundation and $1,000 to $3,000 around a whole house, or about $0.40 to $1.00 per square foot for finish grading and $1 to $2 for rough grading (January 2026). These are national averages, not my prices and not specific to Virginia.

What drainage has to do with the foundation

Daniel Mercer wants to avoid two extremes: soil that stays saturated all the time, and big differences in moisture along different parts of the same foundation. Water can increase the pressure of the soil against basement walls, and it can weaken some soils and contribute to settlement. Clay soils change volume with moisture: they swell when they get wet and shrink as they dry. That doesn’t mean one storm will break your foundation. Problems tend to show up with uneven movement, or with conditions that repeat over time. That’s why he likes drainage to be consistent all the way around the house. He doesn’t want one corner taking all the roof water while the rest stays fairly dry.

Combinations that make him look outside first:

• settlement concentrated at a corner where a lot of water empties;
• stair-step cracking near a downspout;
• a bowing wall with saturated soil outside it;
• erosion near the foundation;
• soil that has pulled away from the wall or settled;
• cracks that change a lot between wet and dry spells.

Still, he wouldn’t conclude that a crack was caused by a downspout just because it’s next to one. It’s a clue. He still has to look at the foundation, the soil and how the loads travel through the house. More in foundation cracks.