While most of the homes built in the Chicago land area since the 1950s have basement walls made out of poured concrete that has not always been the case. Some of the older homes have brick foundations, some have stone foundations and still others have CMU or cinder block foundations. Like the typical poured concrete foundation wall each of these is subject to cracking and subsequent basement seepage. However un-like a concrete foundation there is no proven method of foundation crack injection for these type of foundation. Sure there is the option of an interior drain tile system to collect the water seepage after it has already seeped through the foundation and possibly deteriorate the substrate.
In order to properly seal a masonry or stone foundation the area should be excavated from top of grade down to and below the top of footer. The footer refers to the first portion of the structure that the foundation wall rest on.
The mortar between the brick and or block will be the weakest portion of the foundation wall So after the wall has been completely exposed it will need to be cleaned and inspected for badly corrupted mortar joints and other flaws. Once detected all corrupt areas will have to be cleaned out and then re-filled flush with the existing foundation. Likewise all loose parge-coating will have to be removed and replaced as necessary. The type of waterproof membrane used will depend on the type of foundation it is being applied to. Stone foundations for example are extremely susceptible to surface breakdown. For that reason it is almost impossible to get any traditional membrane to adhere successfully to the stone. There is a whole different set of circumstances to consider when addressing CMU or cinder block walls as they are referred to. The Membrane applications have an easier time bonding to the large face of the actual block but will lose adhesion at the mortar joints.
However because of the scope of the scope of the area repaired the percentage of area where the membrane has maintained its bond is significantly greater than that with the risk of failure. Even with that many manufacturers suggest a primary application of a cement based below grade waterproofing such as “Thoro-seal” prior to installation of the membrane system.
Unlike an interior crack repair there are several different conditions to consider when taking on the cost and as well as the work load involved in securing a complete exterior foundation waterproofing.
Contact us to see how our professionals can help you develop a comprehensive exterior waterproofing package helping you prevent the damage basement seepage through a masonry foundation can lead to.
Written by Walter Slowinski