Basic Types of Drainage Systems

French Drains. With all the recent rain, everyone is getting them, right? When people, even contractors, refer to French Drains, that’s not always what they mean. In most cases, what you actually receive and what you need is an area drain.

There are two basic types of drainage systems – French drains and area drains – each is effective , but for different problems.

The Ins and Outs of Drains

French Drains are designed specifically and only to collect underground water. French drains utilize an underground construction that includes:

  • A trench three to six feet deep, depending on soil conditions
  • Geo-tech cloth or landscape fabric liners – preventing root penetration
  • Perforated or slotted pipe with rocks added nearly to ground level – allowing vegetation growth over the top of the drain
  • Sump box and pipe to direct water into a nearby street or alleyway

These drains are not designed to collect surface water such as rain or sprinkler runoff, gutter downspouts and collection basins should never be connected to a French drain.

Area Drains, also called surface drains, are designed to collect rain and sprinkler runoff, channelling it away from low areas. Construction of an area drain system includes:

  • Collection boxes with a grated top
  • Boxes buried with the grate flush with or just below ground level
  • Connection between boxes by a pipe four to eight inches deep that drains to a nearby street or alley

Gutter downspouts can and should be connected directly to an area drain system.

A rarely used hybrid of the two is called a modified french drain or trench drain and is designed primarily to collect surface water in large areas. This drain is constructed much the same as a French drain with only a few differences:

  • A shallower trench – only one to three feet deep
  • Rocks or gravel filler extend all the way to the surface

As the water flows downa slope, it falls through the rocks into the trench drain, is directed into the pipe and released away from the property.

Every drainage system is custom-designed to fit a specific issue, and pricing varies on the scope of the project. For more information on this and other drainage correction methods, call Structured Foundation Repairs today at 972-484-1200!

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