November 7th, 2019
Interior waterproofing, also known as negative side waterproofing, is the process of applying a protective layer to the dry or inside face of the subsurface. The primary purpose for negative side waterproofing is for water holding. In other words, negative side waterproofing will prevent water from entering a certain space, however it will not prevent water from entering the substrate. Since water will still be in contact with the substrate, this can lead to mold growth, deterioration of foundation material, and other problems associated with moisture.
There are some distinct advantages to interior waterproofing. The major advantage is that it can be much less intrusive than exterior waterproofing. The negative side can be much more accessible as well, making it easier to identify leaks. Overall, interior waterproofing is usually less costly than its exterior counterpart. It entirely depends on which route you go when it comes to waterproofing. Here are a couple of examples of different solutions used:
Injection Waterproofing Method
Sometimes with interior waterproofing, exterior improvements should be made at the same time. An example of this would be extending a downspout outfall 10′ or more downhill away from the foundation. Thus preventing moisture from building up close to your foundation. Another thing to note is that sometimes these interior methods will carry warranties with them, giving you peace of mind to your new waterproofed location.
Exterior waterproofing, also known as positive side waterproofing, is the process of applying a protective layer to the wet or exterior side of a foundation or slab. This can be done grade, below grade, or both. Unlike negative side waterproofing, exterior waterproofing when properly applied will protect the substrate from any moisture. Since the substrate is protected, the structural components are better protected and will typically last longer. The procedure is meant to stop water before it migrates into CMU cores or through cracks in the foundation.
When positive side waterproofing is used, it most often results in much better drainage via a new drain tile/downspout system. The main disadvantage with choosing exterior waterproofing is that it requires enough room to properly create a safe excavation in order to access all parts of the suspect foundation. Therefore, when it comes to new construction, this is usually the method used to waterproof a structure. In addition, it also requires a spot near the foundation to properly outlet the downspouts and the new drain tile system downhill away from the foundation. The system is sometimes inaccessible after installation as well and usually requires the moving of hardscape or landscaping to get to the installed system.
Although exterior systems are typically costlier than the interior, the longevity is much better in the former. Since the substrate is protected, moisture does not have a chance to build up and begin deteriorating the foundation. The risk of ground contaminants and chemicals is always present with moisture so by using the positive side waterproofing, you are preventing these from reach the foundation. There are several different approaches to exterior waterproofing such as:
Blueskin® Composite Membrane
There are quite a number of different vapor barriers and waterproofing membranes that can be used. They have varying degrees of effectiveness, cost, and ease of installation. There are many factors that are considered when determining which approach to use.