french drains

Why Your Basement or Crawl Space Needs French Drains

french drainsFrench Drains

The ideal scenario would be no water ever entering the basement or crawl space at all. However, the nature of the basement and crawl space makes that difficult. The basement and crawl space are below ground and made of concrete, a naturally porous material. Being below grade you have to deal with the natural elements, water in the soil and science. Water from the soil is pulled toward the foundation through capillary action. There has to be a waterproofing system to prevent the water from entering the foundation wall even if there aren’t any foundation cracks. That’s why French drains must be installed too.

Waterproofing System

Even if you choose an exterior waterproofing system, the water that may get into your basement needs to have a way to get out. That is why you need French drains in your basement or crawl space. The interior French drains line the perimeter of the basement or crawl space and filter any water out that may come in. Interior French drains are designed as a trench with a perforated pipe embedded into the floor. The perforated pipes are usually lined with a filter fabric or something to prevent sediment build-up. Then rock or pea gravel is set around the pipe. This gives the water somewhere to go and this in combination with a sump pump system keeps the basement dry.

Dealing with water problems is the number one step if you are finishing your basement or lining your crawl space. If you don’t deal with the water problems first and make sure it will stay dry, you will end up with mold, mildew, rot, and pest problems. Not to mention indoor air quality problems just from having high humidity in your basement or crawl space. French drains help keep the space dry.

2 thoughts on “Why Your Basement or Crawl Space Needs French Drains

  1. I get some shallow pooling during very heavy rains in a few areas of a 500 SQF vented crawl space with about 48 inches between dirt floor and joists; otherwise, the crawl space dirt is damp but not wet. No musty smells in living area above crawl space. HVAC ducts in crawl space are newly insulated. No appliances are in crawl space. Crawl space must stay vented because I am in a flood plain. Also, I can’t can’t afford encapsulation, so how about filling the crawl space with 3-4 inches of gravel and then covering the graveled floors and part way up the walls with 6-10 mm polyethylene, sealing sheets together and to the walls? Won’t this at least mitigate moisture sufficiently to prevent damage to hardwood floors we want to install above crawl space?

    • Hey Linda,

      Thanks for the question! You have to be careful when simply installing gravel without the presence of a drain tile/sump system. The plastic sheeting isn’t going to do much good for you in the event that the water table rises above the level of the gravel—this is especially important being in a flood plain, as you mentioned. Additionally, even though you may not notice an especially musty odor in your living spaces, you still want to be mindful of the potential for mold in an area experiencing frequent moisture and seepage.

      If you’d like to go over your situation in more detail, please feel free to call us directly at (678) 741-2900, and we’ll see if we can recommend a solution that makes sense for your budget.

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