Interior vs. Exterior Drainage Systems

Basement Systems, Inc., a leader in the foundation waterproofing industry, has put together a list of differences between the two methods of basement waterproofing: interior and exterior drainage systems. This information can help homeowners who are buying or selling a home with a wet basement or who are looking for a long-term solution for consistent basement water problems.

Basements are prone to water problems because they're built below grade. Issues can range from damp basement walls or puddles on the floor to severe flooding during rainstorms. Damp or wet basements often have mold and mildew growth, rotted wood, and water and moisture can cause damage to stored items.

If water is coming into the basement from the outside, a basement drainage system can help protect against flooding. Below are some of the common problems associated with exterior foundation drainage and pros and cons of both types of basement drain tile systems.

A before and after of a basement sump pump and drain tile replaced with the WaterGuard interior basement drainage system.

Exterior Drain Tile Systems

Advantages of Exterior Basement Drainage

• Little disruption to the basement interior: Stored items and furniture typically don't need to be moved.
• Improves exterior drainage: Helps drain soil next to the home and reduces pressure against the foundation walls.

Disadvantages of Exterior Basement Drainage

Disruptive Excavation: To install an exterior drain around the perimeter of your home, basement waterproofing contractors will first need to excavate the area around your foundation with a backhoe. Before this can be accomplished, anything around the perimeter must be removed- including porches, shrubbery, gardens, sidewalks, steps, part of the driveway, and anything else that may be sitting near the foundation. Once the earth is dug up from around the foundation, the soil is piled next to the house. The drainage will be installed, and most of the dirt is filled back into the area. This dirt will be fluffed and porous, and will absorb more water than any of the soil around it. Over the years, it will settle back down against the foundation and will require constant regrading to prevent water from collecting and pooling against the home.

Drainage Issues: Unless your home is located on a slope and there is enough room between your house and your neighbor’s to dig a gravity drain, an exterior French drain (also known as drain tile) system will have no natural way to discharge any water collected in the drains downhill. If the water cannot run down naturally from the bottom of your foundation and outside of the home, then the drainage system cannot work on its own power. In cases where the drainage runs to a storm sewer or dry well, that system will need to be significantly lower than the drain’s discharge line, and the amount of water that can be discharged from around the foundation is limited to the holding tank’s capacity from the entrance point of the pipe. In most cases, a sump pump may be installed to pump the water out of the perimeter drainage system.

Expensive Installation and Maintenance: There’s a chance if you’re looking for a basement waterproofing system, your home already had one installed around the exterior when it was built. Why did it fail? Because exterior excavation systems with French drains or drain tile will eventually need service. When they’re installed, they’re laid around the outside edge of the foundation on a bed of gravel. Gravel is laid on top to improve drainage, and a layer of filter fiber is laid on top of this. If there is no filter fabric, the pipes will clog, and if filter fabric exists, then that can clog just as easily. Because these drains are impossible to service without excavating the system again, they’re doomed to clog over time.

When a new exterior waterproofing system is installed, it’s often installed to replace the one that has already failed. Exterior waterproofing systems are much more expensive than interior ones - generally costing about double the price. And because they’re much more accessible to service and maintenance, interior waterproofing systems can last much longer.

Interior Drain Tile Systems

Advantages of Interior Basement Drainage

Fast Installation and No Disruption to Exterior: Interior drainage systems can be installed in a day or two by jackhammering the perimeter of the floor and placing a drainage system on a bed of clean stone. If done correctly, this can be accomplished with a minimal generation of dust in the home and without any long-term or visible disruption of your home. Once the pipes are laid down, they’re cemented back over, making the system almost invisible after installation. No damage is done to the home, the landscaping, or foundation.

Cost-Effective and Low Maintenance: When it comes to waterproofing a basement, installing an interior drainage system is far less disruptive and installs without the long-term need to regrade the soil around your home. They’re much more easily serviced in your home. They’re the superior solution to effective short term and long-term drainage around your home, and they install at half the cost.

Disadvantages of Interior Basement Drainage

• Stored items, furniture, and built-in shelving or cabinets will likely need to be moved away from the exterior basement walls.
• Portions of the basement cannot be used during the installation.

Interior and exterior basement drainage systems each have advantages and disadvantages in terms of the installation and functionality. Interior drainage systems have become a popular alternative to exterior drain tile systems. Basement Systems' WaterGuard Basement Waterproofing System is one of the most innovative drain tile systems on the market. The perimeter basement drainage system is resistant to clogs, easy to service, and is installed by trained, experienced contractors who are part of the largest network of basement waterproofing contractors in the world. Basement Systems offers a full lineup of waterproofing products designed to help homeowners keep their basement dry year round.

Homeowners looking for a professional contractor to help install a basement drainage system should visit the following link to find their local waterproofer: https://www.basementsystems.com/basement-waterproofing/contractors.html

About Basement Systems, Inc.

For over 30 years, Basement Systems, Inc. has provided proven basement waterproofing and crawl space repair solutions to help homeowners keep their homes dry and healthy. Basement Systems offers more than 30 patented products installed by locally-owned companies. Basement Systems is based in Seymour, Conn. and is a subsidiary of Contractor Nation.