What is a perimeter drain?

Offering reliable landscaping services to homeowners in British Columbia since 2013

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Natasha Maerz

Owner/Office Manager

What is a perimeter drain?

A perimeter drain can prevent the headache and worry of how safe your crawlspace or basement is during a rain storm, and truly give you peace of mind that your house and belongings are secure. If your system is not working properly, or worse, you do not have a system, you are going to end up with a wet basement/crawl space.

If we haven’t met before allow us to introduce ourselves. We are Back 40 Landscaping and our expertise is in retaining walls, hardscaping and drainage. We also like to bring education to those looking for retaining wall and drainage solutions.

A perimeter drain is a drainage system that is designed to prevent water from seeping into your basement. It carries the water accumulated from heavy rainfall or melting snow, away from your foundation, keeping your basement or crawl space dry.


How do perimeter drains work?

The foundation around your house is excavated and perforated pipe is placed around the perimeter of your house. The tiny holes in the pipe allow water to enter the pipe, and be drained away from your home’s foundation. The pipe is covered by gravel, and the trench is then backfilled with soil. The gravel allows the water to flow towards the drainage pipe, without allowing dirt and debris to clog the pipe.

The pipe is sloped away from the home, and carries the water to a discharge station.  On your homes foundation a waterproof membrane, generally black tar, is installed. When it rains, the water will hit this membrane, which acts as a foundation waterproofing. As the water table rises, the water enters the perforated pipe, and flows to the lowest point of the system, and to its discharge station.

Indicators that there is a problem with your current drainage system

  • Your basement or crawl space is flooded
  • There are puddles close to your home’s foundation (This is a sign that your yard is not properly sloped away from your home, or that your downspouts are not directing roof water far enough away)
  • You have water stains on your basement walls. (Serious flooding can happen if this is not remedied).
  • Musty smelling basement from water damage

What happens if you do not have a perimeter drain?

The most common problem with a perimeter drain is the drain getting clogged from dirt and debris. The clogged soil can damage your perimeter drain pipes, and the water will have nowhere to do. This excess of water can cause problems like seepage and cracking, due to the pressure it is putting on your home’s foundation. (For more information on perimeter drain problems check out)

One thing to keep in mind with your perimeter drain, is to make sure that when it is installed, it is separate from your gutters. When a downspout is connected to a perimeter drain, substantial rainfall is funneled into one underground location. If all of the water is going to the same location, the drainage system will be overwhelmed, and will result in the drain backing up, causing basement flooding and foundation damage. Instead, the downspout system should be connected to solid pipes, where the water cannot escape.

Who can benefit from a perimeter drain?

Anyone that has a basement, and/or is experiencing water damage or flooding in their basement/crawl space can benefit from having a perimeter drain installed.

It is wise for homeowners to put a drain in BEFORE water issues happen. If you bought a new home and there is no drainage system, get a contractor to install your drain before doing any landscaping, as it will save you money, and be less of a hassle before walkways or plants get installed.