Control Joints in Foundation Walls

Perspective is a very interesting concept. Depending on how you perceive something will drastically affect your logical thought processes. What does any of this have to do with concrete? Well, when it comes to the importance of control joints, it relates very well.

Industry professionals and lay people alike seem to get thrown on the importance of control joints in vertical concrete. Almost all parties agree that concrete slabs need joints to help control where the concrete will crack on flat slabs. However, those same people will not relate to the importance of control joints when the concrete is standing up. Their perspective due to the concretes orientation is different.

Whether concrete is vertical or horizontal it shrinks and cracks during the hydration process. Just because it is vertical does not mean the concrete is under some other mysterious force of nature that prevents it from cracking. A foundation crack is more serious due to the fact that now a place for water to get from the outside is present. Therefore, the installation and drainage details are vital to the performance of the concrete foundation wall.

I have encountered two examples of people realizing the importance but not willing to actually follow through with the details. One example was in a discussion with a vendor a few months back. The vendor was a national corporation selling asphaltic based waterproofing membranes. He called to explain the benefits of his product over our current Tremco Barrier Solutions Tuff N Dri product.

His first sales pitch was delivered in a question. He asked how many foundations we did, how many were waterproofed and what percentage had water intrusion call backs. When I gave him the answer of about five to ten percent were waterproofed and less than one percent had a call back I heard total silence. He then began to query me on how our company could have such great success compared to all other areas of North America. I explained to him about our “Integra” foundation system with the steel reinforcing, concrete mix design, consolidating techniques, and the control joints with the water stop system. Once complete with the explanation he stated that there was no need for him to call us anymore. His waterproofing membrane could not add any more value because we had developed a fool proof effective system. The key, he said, was the control joints and water stop and most people’s perspective is to add the waterproofing band aid and transfer the risk of failure to someone else instead of doing it correctly.

The second example came during a site inspection of one of our foundations. We had just completed a foundation in a newer subdivision and a competitor did a foundation next door. I went over and checked it out. The foundation had just been completed a day earlier and the job was ready for backfill. The thing that jumped out at me was that there were no control joints in the foundation walls. I knew the competitor and that practice was fairly common. A few weeks later when I was in the same subdivision again I stopped back at the freshly backfilled site. Someone must have requested control joints to be cut into the foundation.

Now control joints are good when done per industry standards. However, these were not. What they amounted to was a faux control joint. The joints were only on one side of the foundation, were a total of less than three eighths of an inch deep on a nine and five eighths inch thick wall, and no water stop or waterproofing was done. Standards call for foundation wall control joints to be either formed in or cut in within forty eight hours of the pour, the joint needs to be as deep as twenty five percent of the total thickness of the concrete, should be on both sides of the wall if possible, and some type of water stop or waterproofing should be done so the foundation does not leak when the joint cracks. Now in the eyes of the owner he got a control joint. How effective it will be will be determined over time.

No matter what your perspective, the only way to do concrete right is to put in control joints. If the control joints are in a concrete wall, please make sure they are not an illusion but actually are a functioning part of the overall foundation system.