Step Cracks In Concrete Block Walls

Explanations for the diagonal or stair step cracks in concrete blocks or bricks near a corner include at least these factors.

Step cracks in concrete block walls. Mix the two part epoxy crack sealer. Tuesday june 26 2018 a stair step crack is a diagonal crack but since mortar is usually not as strong as concrete block or brick the crack migrates to the mortar joints as it zigzags along a path of least resistance. A typical cause of diagonal or step cracking in a concrete block wall and some brick or other cmu walls is frost heave or settlement but as you can see in the photo below a collapsing masonry block foundation may also show diagonal cracking near wall corners. Commonly rectangular concrete blocks are manufactured as a solid block of concrete or with hollow chambers.

First scrub the crack clean of any loose concrete paint or old filler using a wire brush. If you notice a stair step crack think of it in the same terms you would a diagonal crack. All of which are anticipated can be predicted and need to be accounted for in design and construction. Apply concrete to any gaps in the blocks or mortar using a shovel.

Remove all dust and debris. Hairline cracking within concrete block walls is the result of internal stresses resulting from shrinkage creep and thermal expansion and contraction. Instead your foundation may be expanding and retracting in response to the weather. Although concrete blocks are strong and durable cracks sometimes develop.

Vertical movement is being caused by settlement frost or a sink hole or expansive clay soils under and near the foundation wall. Fill in the cracks or holes with concrete. Fill the holes and cracks as deeply as you can then scrape the top over with a trowel so the concrete can patch the wall together evenly. The crack will be a result of that rapid change.

Use a nail to align injection points. Hairline cracking within concrete block walls often referred to as stair step cracking or mortar joint cracking is an example of an imperfection or distress but does not typically compromise structural integrity. Concrete wall crack repair in 8 steps.