Before having any type of foundation drain system installed, you must understand what they are designed for. There is a lot of information out there on interior foundation drain systems. The issue is finding information that is not sales propaganda. Knowing the pros and cons of every system is key to making an informed decision.
Interior drain systems are designed as a collection and diversion system. They are not a repair, and certainly not waterproofing. They are widely accepted, and do a wonderful job controlling the leak in your basement or crawl space.
The pros of an interior system are very attractive. They typically cost less than an exterior foundation drain. They require no outside excavation, and can be installed reasonably quick. If you have a slight leak in your basement or a moisture presence in your crawl space, this type of method can control it.
What an interior system will not do is where the sales propaganda takes over. It is not a waterproofing system because it does not prevent water from entering. It is designed to allow the moisture to flow through the foundation wall, collect it below the floor, and then divert it to an evacuation point, such as a sump pump or floor drain. Many contractors install these systems on top of a footer, or level. This can pose a problem as water must build up to a point of “flowing” through the system. This water lays stagnant under the floor until that time. This is why it is recommended, and often necessary, to continue to run a dehumidifier even after the system is installed. A directionally sloped system is best for this application.
If you have bowed walls, an interior drainage system does not address the source of the problem. Interior supports can be installed, and there are many types on the market. Carbon fiber strips, angles, beams, and pilasters all are designed to stabilize a wall in its current location. Correcting the movement of a basement or crawl space wall requires addressing the source; the pressure against the wall. Without removing the pressure, interior support systems can do no more than stabilize your wall in its current location.
How do you determine which is right for you? Ask the right questions of your contractors. Do they install multiple types of systems? Do they offer options on exterior versus interior drainage? Are your needs being considered? How do they handle dust control during interior system installation? Is the system sloped towards the evacuation point?
When correctly applied, and installed, an interior foundation drain is a great option to restore value to your home. When used like a “one size fits all” panacea, it could be a huge waste of money.