If you’re planning to build a home with a basement, your contractor will likely create a block foundation wall first. You’re probably wondering what this is and whether it’s good for your foundation walls, right? Read on to find answers to these and other related questions.
What Are Block Foundation Walls?
Block foundation walls are a type of retaining wall made by stacking hollow concrete blocks and joining them with mortar. During construction, the concrete masonry units are laid on top of the footing. Each row forms its own course until the wall reaches the required height. Block foundation walls usually have a depth of 1.5-2”.
In Virginia, Maryland, and D.C., concrete blocks are widely used to create block foundation walls. Some contractors use blocks made from a mixture of sand and cement while others use stabilized earth blocks. Once blocks are laid, they are reinforced with rebar before concrete is poured to form a seamless slab.
History of Block Walls
People have been using blocks for many years. The first concrete block house in the country was built in Staten Island, New York in 1837. In 1900, Harmon S. Palmer patented the first hollow concrete block design, paving the way for builders to start using blocks made of sand and gravel aggregate.
Locals quickly fell in love with concrete blocks as they were lighter to transport and easier to store than stone or brick blocks. Today, foundation contractors use these blocks to construct foundation walls and below-grade areas. Standard blocks measure 16” x 8” x 8” and weigh roughly 40 pounds.
Advantages of Block Foundation Walls
Thanks to their load-bearing capacity, block foundation walls can carry more weight than poured concrete walls. Block walls can make sturdy foundations if they’re built correctly. Homes or buildings that have these retaining walls will remain stable and structurally sound for years to come.
In addition to being strong, concrete block walls are easy to construct. They can be put up faster than other types of walls. All that a foundation contractor needs to erect them is a mortar mixer, some shovels, trowels, and levels.
You will also be happy to know that block foundation walls are inexpensive to build. If you’re on a tight budget, you can save a great deal by using these walls.
Disadvantages of Block Foundation Walls
If you don’t take precaution to fortify and waterproof your block foundations walls, water can seep in through their cracks. They’re also known to lean, crack, or buckle under pressure if faulty.
Reinforcing Your Block Foundation Walls
Once the concrete blocks have been laid, their voids can be filled with poured concrete or cement-based mortar. We recommend that you use concrete with small gravel, which can flow and fill the narrow voids. To strengthen the concrete walls, insert ½ inch steel rods in the middle of the voids, starting from the bottom.
Problems with Block Foundation Walls
Soil and water pressure are the chief enemies of any block foundation wall. Both can cause the mortar that holds the blocks to break down and wear away. Within no time, water will start seeping through the exterior mortar joints. The trapped water will exert pressure on your block walls and cause them to bow inwards. So, you’ll have to deal with the water that’s infiltrating the hollow block and getting into the basement.
Waterproofing Block Foundation Walls
You need to waterproof your block walls to prevent underground moisture from infiltrating below-grade areas like the basement. After excavation, a waterproof membrane is applied to the foundation walls.
Drain tiles can also be installed around your home’s perimeter to collect and direct away the excess water that’s threatening to get into the basement. Once the tiles are in place, the trench is backfilled and compacted.
Leaning or bowing has to be straightened using wall anchors and cracks sealed with hydraulic cement before exterior waterproofing commences. Left unchecked, small cracks can widen and let more water into the basement.
If you’d like to seal cracks on your block foundation walls or install an interior drainage system in your basement, contact JES Foundation Repair for a free inspection and repair quote. Our experts will take care of all the waterproofing work so your foundation walls stay dry.