The discovery of water in the basement tends to be stressful for many homeowners. Since basement leaks are very common, basement waterproofing is big business. In this post we provide an overview of basement waterproofing, the methods used as well as factors influencing its cost.
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It is important to note that a wet basement floor is not necessarily the result of a leaky basement.
What is Basement Waterproofing?
Basement waterproofing (also referred to as tanking) is the process of preventing or stopping groundwater from entering a basement via the foundation walls or from beneath the basement floor. In some instances it involves preventing water from getting into a basement through the basement windows.
How to Waterproof a Basement
In discussing how basement leaks are prevented or repaired it is important to keep in mind that there are several basement waterproofing repair methods; therefore, the repair method used must take into account the cause of the leak. For example, sealing a foundation is not an appropriate repair for a non-draining window well that is flooding your basement.
In general, waterproofing repairs are classified as internal or external (done from the inside or from the outside). Whether you waterproof your basement from the inside or the outside, your basement will be dry as long as the repair solution is a professional one (not always the case) and it is done properly.
External basement waterproofing
The traditional method of waterproofing a basement is excavation of the foundation for the purpose of sealing the foundation walls with a waterproof coating, installing an air-gap membrane and replacing the weeping tile. This type of repair, while costly and destructive will solve virtually any leak through a foundation wall. It is important to note that the materials used to coat the foundation are of paramount importance.
Click on this hyperlink for more information on external excavation and waterproofing
Internal basement waterproofing
While the process of waterproofing a foundation on the exterior remains the same regardless of the foundation type, internal waterproofing methods can vary dramatically.
Foundations across the Greater Toronto Area are generally constructed using concrete block / cinder block (1930 – 1979) and poured concrete (late 1970s to present). The characteristics of those two foundation types differ significantly; therefore, the foundation repair methods vary accordingly.
Click on this hyperlink for more detailed information on concrete block / cinderblock waterproofing
Click on this hyperlink for more information on poured concrete foundation waterproofing
There is one internal basement waterproofing method that works equally well for both poured concrete and concrete block foundations: the internal perimeter drain system. This particular waterproofing system has the advantage of resolving basement seepage issues related to a high water table through the use of a submersible sump pump. While we do not recommend this system for fixing leaks in poured concrete foundations, some companies use this system to remedy virtually all wet basement problems.
The most common basement waterproofing method for poured concrete foundations is injection, largely due to its very low cost compared to exterior waterproofing and perimeter drain system installation methods, and because an injection can typically be carried out in just a couple of hours. Foundation crack injection is the most common wet basement repair method for poured concrete foundations; essentially the void (crack) is being filled with a pressure injected resin, thereby eliminating the crack.
What Does Waterproofing Cost?
The cost of repairing a basement leak is a major concern for many people. What waterproofing will cost varies considerably and is influenced by the following factors:
- The foundation type (waterproofing a concrete block foundation costs more than for a poured concrete foundation);
- Whether waterproofing is done from the inside or the outside (the cost of exterior waterproofing is typically double the cost of interior waterproofing due to the need for excavation);
- Accessibility of the part of the foundation requiring waterproofing; and
- The repair method used (injections cost a few hundred dollars whereas excavations and internal perimeter drain systems cost several thousand dollars).
Check out our post on the cost of waterproofing a basement in the GTA.