Waterproofing Basement Walls From Inside Only Is Usually Not Enough


When researching the internet, most results show that waterproofing basement walls from inside only is usually not enough to keep moisture out of your basement. This is a misconception, because most people believe that waterproofing basement walls from the inside means installing a vapor barrier. However, a vapor barrier is just that – a barrier against moisture, typically installed in a crawlspace – and therefore, an ineffective method of waterproofing basement walls from inside. In this article, we will discuss other waterproofing methods for waterproofing basement walls, basement floors, and basements in their entirety.

We are going to go over the connection between damp basements and the air we breathe, how basements get wet, how to properly waterproof a basement, the cost of basement waterproofing, and steps you can take – in addition to waterproofing – to keep your basement dry.

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

Damp Basements And Unhealthy Air

Moisture problems are common in basements because they’re below ground. If you don’t use or live in your basement, you might not have a problem with this. However, basements are connected to the rest of your home, which means bad air created by a damp, moldy basement makes its way up and into your living space. That means you’re breathing it in. Yuck.

Of Course, There Are Other Reasons You Don’t Want A Wet Basement

Today, basements are often used as living spaces or for storing valuable belongings, so a wet, moldy basement can lower your property value. Therefore, you’ll want yours to be dry and free from mold and mildew. The only way to achieve this is to thoroughly waterproof your basement. Waterproofing basement walls from inside only (which in our area of expertise does not call for the use of a vapor barrier) is a great start to a remedy.

Sources Of Moisture In Your Home’s Basement

Wet basements are usually caused by excess water in the soil around and under the foundation, along with poor drainage. The excess water can be caused by various things including, but not limited to:

  • Clogged gutters – If water isn’t flowing freely through your gutters, it can spill over the side of your home and into the soil next to the foundation. From there, it will find a way into the basement.
  • Short downspouts – Short downspouts dump water next to the foundation. It soaks into the soil and then into your basement.
  • Improper yard grading – Your yard should slope away from your home’s foundation. If it doesn’t, water will build up in the soil around the foundation and get into your basement.
  • Improperly designed window wells – Water shouldn’t be able to pool inside window wells.
  • Vertical wall cracks caused during the concrete curing process – Vertical wall cracks won’t affect your home’s structural integrity. However, they can allow water to seep into the basement, especially if hydrostatic pressure has been allowed to build up in the soil around the foundation. We’re going to talk about hydrostatic pressure in just a bit.


Sources of moisture in your basement that aren’t related to excess groundwater include:

  • Unvented dryers
  • Kitchens
  • Bathrooms with showers
  • Moisture in newly poured concrete
  • Open windows that allow humid air to enter

Why Waterproofing Basement Walls From Inside With A Vapor Barrier Only Is Not Enough

DIY projects that attempt waterproofing basement walls from inside only with a vapor barrier attempt to stop moisture from getting in with this method that is generally reserved for crawl spaces. While it may be less expensive and work to some extent for a little while, it’s not a long-term solution because it doesn’t eradicate the source of the problem: hydrostatic pressure. Hydrostatic pressure is still there pushing against the wall, and you’re fighting to keep it out. Therefore, the best way to waterproof a basement starts with getting groundwater under control so hydrostatic pressure can’t build up.

So, What Is Hydrostatic Pressure And How Does It Build Up?

Hydrostatic pressure happens when the soil around and under your foundation gets saturated with water that can’t drain off. Eventually, pressure builds up and starts to press against your foundation. Hydrostatic pressure will not only force the water through even the tiniest of cracks and into your basement, but it can also cause cracks in foundation walls.

As long as you have hydrostatic pressure built up in the soil outside your basement walls, you’re going to be fighting a losing battle with moisture. The only way to win the fight is to relieve the pressure via a drainage system.

A Drain Tile System Relieves Hydrostatic Pressure And Is the Best Method of Waterproofing Basement Walls From the Inside Only

A drain tile system is a gold standard when it comes to basement waterproofing. It prevents hydrostatic pressure from building up by channeling excess water in the soil, away from the foundation. Depending on the slope of your yard, the release might be done via gravity drain or a sump pump.

Drain tile can be installed either on the exterior of your home or inside, under your basement floor.

Exterior drain tile

An exterior drain tile system goes along the outside perimeter of the structure at the footing level. It collects and channels excess moisture in the soil and away from the foundation. Most new homes have at least an exterior drain tile system installed. However, exterior drain tile can also be installed for an existing home. The installation procedure is as follows:

  • The first step is excavation down to the level of the footing.
  • A trench is dug around the foundation’s perimeter.
  • The trench is filled with a few inches of gravel.
  • A perforated, socked drain tile pipe is placed on the gravel.
  • The pipe is covered with a minimum of 2 feet of washed drainage stone, and the remainder is filled with soil.

The perforated pipe will now collect excess moisture in the soil and channel it through a gravity drain to daylight.

Interior drain tile

An interior drain tile system goes under the basement floor and prevents hydrostatic pressure from building up under the slab. The excess moisture is channeled into a sump pit and released by a sump pump. The installation is as follows:

  • Everything, including carpeting, is removed from the basement.
  • A jackhammer is used to break up the floor.
  • A trench is dug around the inside perimeter of the basement, along with a sump pit.
  • The trench is filled with gravel, and the perforated pipe is placed in it and covered with more gravel.
  • Concrete is poured over the drain system to provide a sealed system.

The interior drain tile system will now collect excess moisture from water intrusion from under the slab, or through the walls, and channel it into the sump pit, where it will be released away from the foundation by the sump pump.

Other names for drain tile include footing drain, French drain, perimeter drain, and weeping tile.

For more information see What Homeowners Need To Know About French Drain Basement Waterproofing.

Other Things You Can Do To Keep Water Out Of Your Basement

In addition to a drain tile system, there are other things you can do to keep water out of your basement including:

  • Regrade your yard, if necessary – Make sure your yard slopes away from your home so that water doesn’t collect around the foundation. A landscaper or a foundation repair contractor can help you with this. Many homeowners opt to do this themselves as a DIY project.
  • Clean your gutters regularly – If rainwater cannot flow through your gutters, it will spill over the side of your home and soak into the soil next to the foundation. You don’t want this.
  • Install downspout extensions, if necessary – Sometimes downspouts are short and dump water too close to the foundation. Extensions are inexpensive and will release the water at some distance from the foundation.
  • Don’t plant water-hungry shrubs and flowers next to the foundation – You don’t want a reason to pour water into the soil around the foundation.

Cost Of Waterproofing A Basement

The cost of waterproofing a basement will depend on where you live, what’s causing the problem, and the chosen solution. The only way to know for sure how much it will cost to waterproof your basement is to contact a foundation repair contractor for an inspection and repair estimate. Most contractors offer free inspections.

How To Know When Your Basement Needs Waterproofing

Your basement might need waterproofing if:

  • There are pools of water on the floor.
  • Water is trickling down the walls.
  • There’s a general feeling of dampness.
  • The base of the wall is saturated.
  • The basement smells of mold and mildew.
  • There’s visible mold and mildew.
  • There’s deterioration in the carpet and/or wood items.
  • The concrete is starting to deteriorate.
  • There’s a white discoloration on the concrete that looks like salt.

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

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