One of the most common trench drain questions we receive is from homeowners who need help solving driveway drainage problems.
(Q) My driveway slopes down from the road toward the house. Rain water tends to flow into the garage and lower house during heavy down pours. How can I stop my garage from flooding?
(A) Installing any drainage system in your driveway will help. However, you need to know how much run-off water to expect from a heavy downpour. A simple 12″x12″ square catch basin drain might be adequate. However, small drains can become clogged by leaves and trash, which will put your garage and basement “back in the drink”.
If you are going to install a drain in an existing driveway, I recommend putting in a trench drain system. You will need to cut and patch the concrete or asphalt driveway no matter which system you use. There will be more cutting and patching with the trench system. However, with the trench drain system, you will receive far more drainage for the amount of work applied to the project. (For another article on a driveway trench drain installation, follow this link.)
Again, the size of the trench drain will depend on the driveway dimensions and anticipated rain fall. For small driveways with light automobile traffic, a 4 inch wide (inside dimension) trench drain with a Class B grate should be adequate. For longer driveways that generate scary amounts of water, use an 8 inch wide trench with a cast iron grate.
To ensure that your driveway is properly drained and that no water makes it into your garage or basement, make the length of the trench drain 80% – 100% the width of the drive.
You are going to need to drain the rain water away from the trench drain, as well. To do this, dig a trench in your yard and place a drain pipe from the drain system to the nearest storm sewer or hillside. Use the flexible perforated 4″ diameter black pipe that is commonly used in french drains. Be sure to place coarse gravel around the drain pipe so that you don’t fill the perforations with dirt. This drain pipe will help keep your yard drier, as well.