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Block Foundation Wall

A lot of homes in the U.S. were built with block foundation walls. However, if you want them to serve you for years to come, you need to waterproof them.


When building a home, contractors first start with the foundation. Foundation walls can be made of poured concrete or concrete blocks. Here, we will talk about the latter.  

Whether you are just building your new home, or you live in a house with block foundation walls, here is everything you need to know about block foundation walls. 

block foundation wall

What Are Block Foundation Walls? 

Block foundation walls are retaining walls that are made of concrete blocks. During construction, concrete blocks are stacked and joined with mortar. These masonry units sit on top of the footing and are stacked until the wall reaches the desired height.  

Block foundation walls are usually eight to 12 inches deep. In Mississippi, Alabama, Georgia, and Tennessee, a lot of homes are built with block foundation walls. While some contractors prefer bricks that are made of sand and cement, others use stabilized earth blocks. When the blocks are in place they are reinforced with rebar, after which concrete is poured to create a seamless slab. 

History of Block Walls 

Block walls are not a novelty. According to records, the first home that was constructed with concrete blocks in the U.S. was built in 1837 in Staten Island, New York. In 1900, Harmon S. Palmer patented the first hollow concrete block design and since then, builders have been using them. 

Concrete blocks quickly became popular since they were much lighter than stone and brick blocks, as well as easier to transport. Nowadays, builders use these blocks to create foundation walls. Standard blocks are 16” x 8” x 8” and weigh about 40 pounds. 

Advantages of Block Foundation Walls 

Due to their load-bearing capacity, block foundation walls can bear more weight than foundation walls made of poured concrete. If everything is done by the book, these walls are very sturdy and homes that sit on top of them can remain stable for decades to come. Also, concrete block walls can be quickly constructed with a mortar mixer, shovels, trowels, and levels.  

Another reason why homeowners often opt for this type of foundation wall is the price. Block foundation walls are a very affordable option, so they are ideal for those who are on a tight budget. 

Disadvantages of Block Foundation Walls 

Of course, block foundation walls are not without flaws. If you do not invest in waterproofing measures, water can seep in through the cracks. When this happens, humidity levels in your basement rise, leading to mold growth and other issues. 

If block foundation walls are not built properly, they can lean, crack or buckle under pressure, compromising the structural integrity of your home. 

Reinforcing Your Block Foundation Walls 

The space between the concrete blocks is most often filled with poured concrete or cement-based mortar. It is recommended to use concrete with small gravel, so it can easily flow and fill even the narrowest voids. To reinforce block foundation walls, contractors will insert ½ inch steel rods in the middle of the voids, starting at the bottom and moving upward. 

Problems with Block Foundation Walls 

Soil and hydrostatic pressure are the archenemies of block foundation walls. They can break down the mortar that is holding the blocks together and cause it to wear away. When that happens, water from the soil that surrounds foundation walls will start seeping through the exterior mortar joints. The walls will also begin to bow as a result of the trapped water exerting pressure on your block walls.  

Waterproofing Block Foundation Walls 

Block foundation walls can serve you well and support your home for years to come, but you need to make sure that the moisture from the soil that surrounds them cannot infiltrate them. You can achieve this by investing in waterproofing solutions

One of them is a waterproof membrane. This solution is applied to the foundation walls after excavation. Another option is to install drain tiles around your home’s perimeter. Their main purpose is to collect the excess water and direct it away from your home. This way it won’t get a chance to infiltrate the walls and enter your basement. These tiles are buried in a trench, which is backfilled and compacted once everything is in place. 

The best options for inside your basement are an interior drainage system to collect leaking water, a sump pump to remove this water, and a vapor barrier to prevent moisture intrusion, just to name a few. 

In case your foundation walls have started to lean or bow, your local contractor can use wall anchors to prevent further shifting. These anchors will not only permanently stabilize your foundation walls but can also straighten them over time. With wall anchors, you can prevent wall failure and restore the structural stability of your home. Wall anchors are made of galvanized steel, so they are rust resistant. If you wish to finish your basement you can do that even with anchors in place since they won’t cause you to lose valuable living space. 

If your foundation walls have begun to crack, it is important to seal them as soon as possible so that they do not widen in time and let water into the basement. 

Are you building a home with block foundation walls and you want to waterproof them? Or maybe you are experiencing issues with your foundation and you want to consult with a professional? In either case, contact experts at AFS to schedule a free inspection and repair estimate. Our team will take care of all the waterproofing measures so your foundation stays dry and stable. 

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