French Drain Installation

This is the classic. A trench across or along the wet area collects water that is sitting in the top foot or two of soil and carries it out.

If water is sliding downhill through the soil toward your foundation or your patio, you cut it off before it arrives. A curtain drain sits across the slope, upslope of what you are protecting, and sends the water around it. Its location matters more than its length.

Homes just below a neighbor's higher lot are the usual candidates, a common setup on sloped lots, including drainage and excavation in Princeton.

Where water collects against the outside of a foundation wall, a deeper drain beside the footing can lower the water level there. It costs more because the trench is deep and access is tight, so we check first whether regrading or downspouts would do the job.

Not strictly a French drain, but often the real fix. Roof water goes into closed pipe and travels well away from the house to its own outlet. It never touches the perforated line. Our trenching work covers these runs.

A daylight outlet is the end of the pipe at the surface of a downhill slope, where water simply flows out onto stable ground. It is the best option when the lot has fall. A dry well is a buried chamber of stone that holds water and lets it seep out, and it is what we use on flat lots. Our page on yard drainage solutions covers how we choose.

On the Princeton Ridge, Neshaminy and Legore soils form from diabase and carry a clayey subsoil. Readington soils, found over the shale and argillite, have moderately slow permeability. Water does not soak down quickly there. It sits, and in a wet season it shows up in your lawn.

Diabase breaks down into boulder fields, and rock can be shallow. A trench that hits a boulder or ledge has to change depth or path, which moves the price. On the lower parts of the Ridge, clay over rocky soil can leave the ground seasonally wet, so water collects in places that look dry in August.

Digging the trench is the easy half. In slow soils a dry well drains slowly, so it has to be sized generously. Near Stony Brook or the Millstone River, the natural low spot may be a stream corridor with its own rules. We look for the outlet first and plan the trench backwards from it. In places like West Windsor and Lawrence Township, where lots can be flat, that often means a dry well, not a pipe to daylight.