How do you waterproof a basement on the outside?

There are plenty of things a homeowner can do or have done to waterproof his or her basement from the inside, but that doesn’t mean the outside should be neglected. For a foundation and basement walls to be completely waterproof, you need to cover all the bases.

Outside foundation and basement waterproofing require excavation around the site where the issue likely is or excavation around the perimeter or along more than one length to set up a drainage system. If there is a crack on the outside, it needs to be properly sealed before proceeding with any drains.

The person you hired should apply a waterproofing product to the walls. He or she also may put up a dimple board. A dimple board is a plastic sheet that helps protect the waterproofing product and direct sediment downward. Another option is a waterproof membrane sprayed onto the foundation. The membrane is flexible but also should be protected by a dimple board.

Once the cracks, support, and any other issues have been addressed, it’s time to move on to installing a drainage system, of which there are different types. Most drainage systems work best on the home’s interior, but there are a couple of simple ones specific to the outside of the home.

Seeping wall cracks can be permanently repaired from the interior as well by injecting them with expanding polyurethane that seals the crack to the outside soil and remains flexible after curing to prevent re-cracking from minor foundation movement.

There are, however, methods of basement waterproofing that can be done only on the exterior of a home’s foundation, and they are the most effective ways of stopping seepage from certain sources.

We have a wide range of external waterproofing services at Hitch Property Constructions.

The Differences Between Damp-proofing vs. Waterproofing Your Basement

When you hear the terms “damp-proofing” and “waterproofing” in regards to your home’s basement and exterior foundation, is there a difference? What do these terms mean?


There are differences – and these differences are extremely significant!

Exterior damp-proofing is the process through which a liquid asphalt-based product is applied thinly to your foundation. Since there is no rubber, damp proofing does not provide any crack-bridging capabilities. Damp proofing done during the construction phase of a home aims to meet only the minimum building code standards and costs approximately $20-30 dollars to cover 100 feet of any foundation. Homes built prior to 1980 do not have the protection of damp proofing or waterproofing, leading to the deterioration of their foundations. Although damp proofing protects from some dampness, it cannot withstand water penetration.

Exterior waterproofing is a process that waterproofs and seals foundations by bridging cracks or faults caused by movement. RCC’s commercial-grade product, Hydro Guard, is used in our main waterproofing process. It is applied in a two-layer application method and costs $200-250 dollars to cover 20 feet. The usage of a commercial-grade waterproofing product allows RCC to guarantee 50-year protection against dampness and water penetration, unlike damp-proofing.

Note: When waterproofing your home, be cautious of the products used to complete the work. Many contractors and waterproofers will promise to do waterproofing, but use damp-proofing products to reduce the cost of their materials.

How Water Enters from the Exterior

Typically, exterior waterproofing is most effective in helping water issues coming high on the basement walls. The soil around your home swells and contracts depending on the moisture level. This swelling and contracting can cause instability which leads to shifts or cracks in your basement’s foundation. Cracks can then allow water to enter your home. Not all cracks are visible, and an added concern is that moisture and condensation buildup can also cause havoc to your home’s basement even if there are no cracks in your foundation. This happens due to the porous nature of the concrete itself, which is not a good deterrent for moisture.

60% of homes today have moisture problems, which is why waterproofing is so important.

Waterproofing Advantages

  • Prevent Damage
  • Add Value
  • Increase Resale Value
  • Peace of Mind

Methods of Waterproofing

  • Minimal Disruption
  • Minimal Excavation

There are several methods of exterior waterproofing. Advanced basement’s techniques work to minimize the disruption to not only the landscaping but also to the homeowner and the community as well. The advanced basement does not use heavy equipment when completing exterior waterproofing projects. The average depth of excavation needed to effectively waterproof is only around eighteen inches.

Subsoil Drainage

Yard Drains (French Drains): French drains can not only be installed inside the basement of your home, but they can also be installed on the outside of your home. Exterior French drains simply direct water away from your home, which prevents subsurface water from accumulating and adding stress to your foundation, causing it to become weak and even cracked. Yard drains are easily and quickly installed by an experienced waterproofing expert and will cause minimal disruption to your lawn and landscape.

Driveway Drains 

Driveway drains are another type of drainage but vary in the fact that they are installed in a driveway. They serve the same purpose as a yard drain by directing water away from home and towards a drainage area. Driveway drains have metal grates that keep debris, such as leaves and sticks from clogging the drainage pathway. Depending on the path of the water, a driveway drain can be a great, attractive solution to prevent flooding and water damage to the home.

Downspout Lines 

Downspout lines or downspout drains connect directly to your home’s downspout and direct water away from home. If gutters and downspouts are overworked or inadequate for the amount of rainfall, then water will begin to accumulate in one or more areas of the soil, causing swelling. This swelling of the soil can affect the stability of the home’s foundation and cause damage. In addition, the subsurface or surface water present may be able to slip into the foundation through cracks which will cause interior flooding. Installing a downspout line is one preventative option a homeowner can take to prevent water seepage into the home and costly foundation damage. Downspout lines are easy to install and like other exterior waterproofing methods, cause minimal disruption to your home’s yard and landscaping.

Waterproofing a Basement on the Outside

One good reason for waterproofing a basement from the outside is that outside is where the water is. Water that enters a basement comes from the soil surrounding it, either below the foundation or around it. 

Water absorbed by soil causes the soil to expand, to a degree depending on what kind of soil is involved. For example, the sandy soil that is common in northwest Indiana doesn’t expand much because the sand in the soil creates more openings between particles, which allow the water to drain through the soil better. 

On the other hand, the clay soil that is common in much of the Midwest, especially around Chicago, is regarded as highly expansive soil, one that allows very little drainage and absorbs lots of water. The particles of clay soil are smaller and more tightly compacted (as any Chicago-area homeowner knows who has tried to dig a hole in the yard), and the soil swells accordingly when saturated.

All this expansion and swelling creates pressure around the foundation. That pressure can essentially push water through any small opening – a crack, porous spot, unsealed utility opening – and create seepage in the basement.

Dealing with seepage caused by this lateral pressure from over-saturated soil usually requires an exterior method of basement waterproofing. It can also be alleviated by exterior work that is not specifically waterproofing but related more to water management and keeping it away from the foundation.

Looking for external waterproofing Melbourne? Check out Hitch Property Constructions.

So, how is basement waterproofing done on the outside?

Exterior Waterproofing Membrane  

Sometimes a foundation wall leaks. For example, a poured concrete foundation wall, the most common in modern residential construction, can have porous spots in the concrete that were caused during construction, either by the concrete not being thoroughly mixed, allowing aggregate or dry cement to form a pocket, or by insufficient vibration of the poured wall to remove trapped air. These porous spots can, over time, allow water to seep into the basement.

In a masonry wall, a common source of seepage is a crack or deterioration of mortar joints between masonry units. Mortar joints may crack because of minor foundation movement and deteriorate due to repeated movement or because of a faulty installation. The average wall can have hundreds of running feet of mortar joints, and that means a huge expanse of potential seepage problems.

Also in masonry walls, the masonry units, particularly concrete block and brick may be porous enough to allow water to migrate through over time. Concrete block is especially vulnerable because water that seeps in through the outer side of the block can collect in the cavities and seep through the porous inner side.

Finally, a foundation wall of any construction may have water seep over the top edge of the wall, especially if the grade of the lawn outside is negative — sloping toward the house — or if decks, patios or other adjoining structures were built improperly.

The remedy for all of these problems is the same – install an exterior waterproofing membrane to create an impenetrable water barrier on the outside of the foundation.

The first step in installing an exterior waterproofing membrane is to start digging. The foundation must be excavated down to the footings, which may be as deep as eight feet in a full basement. The excavation must also be several feet wide to allow room for technicians to work, and it can range in length from just one affected wall to the entire perimeter of the house.

After the excavation is complete, the installation begins by cleaning soil and loose mortar or concrete from the wall. On a masonry wall made of stone or coarse brick, a parge coat of mortar is applied to even out the surface and is left to cure before work continues.

Once the wall has been prepped, the technicians use masonry trowels to apply a thick coating of asphalt-modified polyurethane. The dark colour of the material often leads to it being misidentified as tar or roofing cement; it is a special sealant formulated for use below ground, and neither of these materials is an adequate substitute.

When the membrane has cured, it forms a seamless barrier around the foundation that not only keeps out water but can aid the structural integrity of the wall. Frequently, insulating material on a roll can be applied over the membrane as can be heavy-duty plastic drainage board. The drainage board will help to protect the membrane and will channel water downward. Any covering placed on the membrane is attached with clips that are set into the wall before the membrane is applied so that they are sealed in place.

The excavation is then backfilled, and the foundation is permanently protected against seepage. There is, however, an addition to the exterior waterproofing membrane that can make it even more effective.

Exterior Drain Tile  

When the groundwater surrounding a foundation is extremely high, it benefits the homeowner to install exterior drain tile along with the membrane to alleviate pressure on the walls and drain off the water. 

To install exterior drain tile after the membrane has been completed, a bed of washed gravel is laid at the bottom of the excavation. A system of perforated PVC pipe is then constructed to lay even with the footings the entire length of the excavation and is connected at one or both ends to a sump pump or allowed to drain to daylight. The pipe is normally encased in a “sock” of filtration fabric to keep dirt out of the system.

The pipe is then covered with more washed gravel, and the excavation is backfilled. The drainage board mentioned above will help conduct water down to the drain tile, and the homeowner will enjoy the benefits of a comprehensive and extremely effective exterior method of keeping his or her basement dry.

Installing an exterior waterproofing membrane or exterior drain tile is quite an undertaking. Still, there is one other form of basement waterproofing that can be done quickly and effectively on the exterior.

Exterior Crack Repair 

As noted earlier, foundations constructed of poured concrete are the most common variety found almost anywhere. The most common source of water seepage in a poured concrete foundation is a non-structural crack in the basement wall. Such cracks can be caused by the foundation settling or by the same lateral pressures that cause other forms of seepage.

Usually, these cracks are repaired on the interior of the basement by injecting them with expanding polyurethane. However, when the basement is finished, or access to the crack is blocked by a furnace, water heater or other obstruction, the crack can also be repaired on the exterior.

Exterior crack repair begins by digging, too, but on a much smaller scale. A small-diameter hole is dug next to the foundation at the site of the crack. The hole extends down to the foundation footings.

Once the excavation is complete, the hole is filled nearly to the top with a granular form of sodium bentonite clay. This granular clay will absorb water from the ground surrounding it, which will cause it to become plastic and form a pliable, permanent barrier against water that runs the length of the crack. The soil or sod is replaced, and the repair is invisible.

Waterproof Your Basement from the Exterior Wall, Before Water Enters

Waterproofing your basement from the outside wall helps to stop the water before it enters your basement. This differs from interior waterproofing in both the concept and scope of repair.

Unlike interior waterproofing, which first allows water to seep into the basement before managing it away, this method of water management is designed to help prevent water from ever entering the basement.

Exterior waterproofing is a highly effective waterproofing method and can be completed on basements with both poured concrete or masonry block walls.

Exterior basement waterproofing involves digging out the dirt around basement walls, applying a moisture barrier and installing a specially designed dimple board that deflects water away from the wall.

Exterior Basement Waterproofing Includes 5 Lines of Defense

  • Exterior basement wall waterproofing diagram installation of an exterior moisture barrier & dimple board on the exterior basement wall to transport water to the drainage system
  • Moisture membrane provides protection from outside water table and seepage
  • 3/4” washed gravel replaces dirt to relieve built-up hydrostatic pressure and ensure water passage to the footer drainage system
  • Footer drain is placed outside of the home to discharge water away from the foundation safely
  • Sump pump installation with available dual pumps or gravity discharge as needed

At Hitch Property Constructions, we offer Melbourne external waterproofing services. 

Important Considerations

  • Work performed outside, no disturbance to the interior of your basement, making it a great choice for homeowners with finished basements
  • A sump pump system is sometimes recommended, but may not be necessary
  • Longer installation time compared to interior waterproofing
  • Products are serviceable
  • Includes exterior wall waterproofing with moisture barrier, dimple board and exterior drainage

Whether the source of the problem is a wall crack, bad mortar joint or patch of porous concrete, there is an exterior waterproofing solution that is made to order. Still, only an experienced basement waterproofing contractor will be able to recommend and implement it.

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