What Homeowners Need To Know About French Drain Basement Waterproofing


French drain basement waterproofing doesn’t simply prevent moisture from entering your basement by erecting a barrier the way a waterproofing sealant does. It works by preventing excess water from building up in the soil around your foundation.

When most homeowners think about basement waterproofing, they imagine creating a waterproof barrier using sealants and waterproofing paint. While this might help to some extent – at least for a little while – it’s not a long-term basement waterproofing solution because it doesn’t address the root cause of the problem: excess water in the soil outside your foundation walls.

French drain basement waterproofing prevents water from building up in the soil. If there isn’t any excess water in the ground, there won’t be any water in your basement.

Other names for this basement waterproofing method include – but aren’t limited to – drain tile, weeping tile, perimeter drain, footing drain, foundation drain, and curtain drain.

There are two types of French drain basement waterproofing: interior and exterior. We’re going to talk more about each type in just a bit, as well as the cost and additional ways you can keep the soil around your home’s foundation dry.

For more information about basement waterproofing see Waterproofing Basement Walls From Inside Only Is Usually Not Enough.


What is French Drain Basement Waterproofing?

French drain basement waterproofing involves using a perforated pipe to collect excess water in the soil and then release it away from the foundation via gravity or a sump pump.

Basement waterproofing via a French drain is a highly effective solution that works by preventing water from building up in the soil under and around your home’s foundation. Your basement stays dry not because water is being held back but because the water isn’t even there. The water has been channeled away from the foundation via the French drain.

The French drain was invented by the 19th-century American inventor, Henry French, and today, just about every new home is built with an exterior French drain. In many municipalities, it’s even required for all new homes.

French Drain Basement Waterproofing Works Because It Relieves Hydrostatic Pressure

French drain basement waterproofing prevents hydrostatic pressure from building up by collecting and channeling excess moisture in the soil away from the foundation.

Because basements are below grade (i.e., underground), they’re susceptible to water intrusion. If there isn’t good drainage around a foundation, hydrostatic pressure will build up in the soil and press against the foundation walls. Eventually, if the pressure isn’t relieved, water will get into the basement via tiny cracks in the foundation. Hydrostatic pressure can even cause foundation walls to bow inward and crack.

Most new homes built in the US have French drain basement waterproofing already installed. However, French drain basement waterproofing can be installed in existing homes as well.

French Drain

Two Types of French Drain Basement Waterproofing: Exterior and Interior

Exterior French drain basement waterproofing is installed around the outside perimeter of the foundation at the footing level.

Installing this type of exterior waterproofing in an existing home is a major construction project because it requires excavation down to the footer. The installation procedure is as follows:

  • The contractor first excavates down to the footer.
  • A waterproofing product is then applied to the foundation wall, followed by a protection board.
  • A shallow trench is dug beside the footer along the perimeter of the foundation and filled with gravel.
  • A perforated, socked pipe is placed in the trench and then covered with more gravel as needed. Depth of gravel can vary.
  • Finally, the contractor replaces the excavated soil.

Excess water in the soil will now flow through the pipe and be diverted away from the foundation via gravity or a positive drain.

Interior French drain basement waterproofing is installed under the basement floor. It prevents hydrostatic pressure from building up in the soil under the foundation by channeling excess water into a sump pit, where it’s then ejected away from the foundation.

Installing this type of waterproofing will mean using a jackhammer to break up the basement floor. After that, the installation procedure is as follows:

  • A trench is dug around the inside perimeter of the basement and then lined with gravel.
  • The perforated, socked pipe is placed into the trench and covered with more gravel.
  • A sump pump system is installed and connected to a drain system.
  • Wall flashing is installed on the basement wall to exterior grade height at a minimum.
  • The section of concrete basement floor is replaced to create a sealed system.

How Much Does French Drain Basement Waterproofing Cost?

The cost for French drain basement waterproofing depends on various factors, including where you live, the size of the repair, and how easy (or difficult) it is to access the area of repair.

Is This a DIY Project?

We don’t recommend you attempt French drain basement waterproofing as a DIY project. Installation is a major construction project requiring either excavation down to the footer (for an exterior French drain) or using a jackhammer to break up your basement floor (for an interior French drain). It’s better to leave this job for the pros.

Additional Methods for Keeping Water Out of Your Home’s Basement

If you want a dry basement, you don’t want excess groundwater near your home’s foundation. Here are a few things you can do in addition to French drain basement waterproofing:

  • Don’t plant vegetation that needs a lot of water near the foundation – The excess moisture in the ground will find a way into your basement.
  • Make sure your yard is graded correctly – The yard should slope away from your home’s foundation. If it doesn’t, have it regraded by a landscaper. You could also DIY.
  • Clean your gutters regularly – Clogged gutters cause water to spill over the side of your house and into the soil next to the foundation.
  • Install downspout extensions, if necessary – You don’t want downspouts releasing water next to the foundation. Extensions will channel the water away from the foundation before releasing it.

While French drain basement waterproofing might cost a bit more than simply using a sealant on your basement walls, it’s the most cost-effective solution. It doesn’t merely hold back the water, it actually removes the excess water from the soil.

For more information about waterproofing see Waterproofing 101: Homeowner’s Guide.

If you’re in our service area in Middle Tennessee and Southern Kentucky, contact us today for a free inspection and repair estimate.

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