Popular Methods of External Basement Waterproofing

Basement waterproofing has become increasingly popular as homeowners have sought to convert rough basement space into living space. Waterproofing techniques and strategies can be grouped into two major categories: External and Internal. In this article we will explore popular methods and techniques of waterproofing basement walls externally.

Why waterproof your basement walls externally? Isn’t it true that internal waterproofing is more popular and cheaper? Well generally speaking, yes. Internal methods are very popular and many of them can be extremely affordable. However, strictly speaking internal basement waterproofing is not really waterproofing at all because you’re not preventing water from entering the basement walls. Rather, you’re devising methods of dealing with the water once it does enter. On the other hand, when you waterproof your basement walls externally you are actually preventing water from entering them in the first place. This is important because water is naturally destructive to building materials. Over time constant water exposure breaks down the composition of any material even the mortar and block of which most foundation walls are built.

So what can be done to the outside of your basement walls? Well, exterior basement waterproofing really boils down to two types of strategies: drainage and barriers. There is also a third strategy known as diversion which can be thought of as an adjunct to drainage. Drainage means you’re installing systems to drain water from the ground surrounding the basement. Considering that water follows the path of least resistance, you’re giving the water an easier path to follow than to enter your foundation walls. Diversion systems refers to the rain gutters and downspouts on your house. These systems are designed to divert that rain water away from the ground surrounding the foundation and therefore not place any undue burden on the drainage system. Barrier systems involve applying a waterproof coating to the outside surface of your foundation walls. This way the small amount of ground moisture in contact with your basement walls will still not enter because it can’t penetrate the waterproof barrier. All of the products, devices, and techniques available for external basement waterproofing fall into one of these three categories. Furthermore, they are all more effective if employed in concert with one another. basement waterproofing nj

Both barrier and drainage methods have something in common. They both require substantial excavation around the structure to expose the basement walls. This excavation represents the majority of the cost of exterior waterproofing and is probably the biggest reason most homeowners opt for interior solutions. Excavation is not only costly but it is disruptive and risky. An inexperienced operator can actually damage your foundation walls with an excavator. Excessive excavation at any one point can cause shifts in your foundation walls. Finally, there’s always a chance that excavation can damage an underground utility line that was either incorrectly marked or just not know about. All of these possibilities can add substantially to the cost of the project. Despite the risks and costs associated with external waterproofing the benefits may still make it a worthwhile endeavor.

Exterior drainage systems are usually referred to as footer drains or tile drains. These systems are comprised of a channel that is dug around the perimeter of the foundation walls at a depth just below the wall footer. The channel is filled with an aggregate, in other words, gravel. In the middle of the aggregate lies a pipe. The pipe has perforations that allow liquid water to enter. As ground water descends it finds little or no resistance to entering the trench because of the abundance of air spaces within the gravel (aggregate). Once in the trench, the water also easily enters the pipe through the perforations. The pipe then leads to a remote drainage location such as a storm drain or a natural ground water drainage path.



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