Construction of a Tile Drainage System for a New House

Underground drain tiles protect a new home from water damage.

Poor drainage around a home can create a number of problems for the foundation, including leaks and mold. Installing an underground tile drainage system around the immediate perimeter of the house is an effective way to capture and carry underground moisture to a safe outlet. Constructing the system is a labor-intensive process, but when installed properly, a tile drain system can last for years with light maintenance.

Lay the Course

Making the trench for the system involves a lot of digging, so it’s important to plan out the course of the system prior to breaking ground. Use stakes and string to create a basic outline for the trench. Space the inner wall 3 feet from the foundation and make the width 10 inches. If the basement has a sump pit, plan for the course to end outside of the basement wall closest to the pit. For a home without a sump pit, the trench should wrap around the exterior and extend to a dry area of the yard, drain ditch or other outlet.

Dig the Trench

If possible, use an excavator machine to remove the topsoil from within the outlined area. Dig down a foot deeper than the foundation with the machine or a trenching hoe and shovel. Once the entire trench is excavated, go to the beginning of the trench and dig down 1/8 inch more with every foot of length. Make this slope a smooth, consistent decline and check it with a measuring stick. For instance, the beginning of the trench should be 1 inch higher than the point 8 feet away.

Install Drain Tiles

The drain tiles should be laid over 6 inches of clean gravel. Cover the top of the gravel with water filtration fabric to keep silt from floating up and clogging the tiles. Set 4-inch perforated PVC drain tiles in the center of the trench, and connect the joints with elbow, tee or wye fittings, depending on the angle of the joints. The remaining expanse should be filled in with more clean gravel until it is 6 inches from the surface. Lay another strip of filtration fabric on top of the gravel as an extra buffer against large debris.

Disguise the Tiles

The final 6-inch expanse should be filled with topsoil. While using gravel keeps the pipes more accessible in case of a clog, most clogs can be removed using a drain snake through either of the open ends of the system. Using topsoil allows you to plant flood-resistant shrubs or groundcover that will thrive from the excess moisture and conceal the system below.

References

• Easy Digging: How to Find the Slope

Resources

• Waterproofing Key: Drain Tile Systems