Is your home plagued by a wet basement or crawl space, with water entering whenever it rains. Or maybe your yard is bog-like, rendering it useless in the wet season.
If so, you’ll be happy to learn that you can have a dry yard and crawl space for less than $500 and a few weekends of moderate labor. The key is capturing the subsurface water, or groundwater, that is causing the issue and redirecting it away from your home to another area of the property.
To understand groundwater and how it moves, you need to first understand the soil around your home.
Some soils drain very well, such as the ground around my house in central New Hampshire. Typically, soil here is thin and very sandy, a result of the erosion of the granite bedrock. However, the soil in Cincinnati, my hometown, is the exact opposite. Beneath the thin topsoil are several feet of dense clay — and water doesn’t travel down through clay at all.
Topsoil almost always has lots of air in it. Insects help create these void spaces. When it rains, water soaks into the topsoil and displaces the air. When the topsoil can absorb no more water, it starts to flow overland.
After that, gravity takes over. This amazing force of nature starts to pull the water down, and because it wants to take the path of least resistance on its journey back to the ocean, the water in the soil usually starts to travel sideways through the topsoil. In most soils, the resistance to movement increases with depth.
A dense clay subsoil, as well as bedrock close to the surface, encourages this sideways movement. Some of the water moving through the soil finds cracks in the bedrock and flows down to fill them. This is what keeps drilled wells filled.
But to stop water from entering your basement or crawl space, you need to capture the water that’s moving sideways through the soil. Remember, water likes to take the path of least resistance, so create one for it that bypasses your basement, crawl space or yard. This project, which I’ve had success with, will help you do just that.
First, dig a 6-inch-wide trench about 24 inches deep. Add 2 inches of washed, rounded gravel in the bottom of the trench. The gravel is about the size of green grapes, and it shouldn’t include smaller stones or sand. You want lots of air space in the gravel, because the water would rather flow down through this gravel and into a buried drainpipe than try to push its way through the topsoil.
Next, place a 4-inch perforated drain pipe on top of the 2 inches of gravel. I prefer to use the solid-white ABS or PVC plastic pipe that has rows of holes drilled in it, rather than the black corrugated drain pipe with the narrow slits. Always install the pipe so the rows of holes point down. If the holes point up, the gravel that you put on top of the pipes can block the holes.
Once the pipe is installed, fill the trench with gravel to within 1 inch of the surface.
The pipe needs to extend to a low spot on your land. As the ground falls away from your house to the low spot, the pipe will naturally pop to the surface if you install the pipe level or have a minimal amount of fall to it. The pipe needs to break through to the surface so it can disgorge the water it’s collected and send it on its way.
Don’t put a fabric sock on the pipe or line the trench with a filter fabric. Those are designed to keep gravel under parking lots and roadways from being fouled with mud. Water flowing through topsoil has already been filtered of this silt, so fabrics are unnecessary.
Tim Carter has worked as a home improvement professional for more than 30 years. To submit a question or to learn more, visit AsktheBuilder.com.