According to almost home stair step cracks in cinder block foundation walls usually found in unfinished basements are a result of soil settling beneath the center of the wall.
Step cracks in concrete block walls.
As a home or structure settles for example sideways or shifting force can put pressure on the concrete block resulting in a crack.
Commonly rectangular concrete blocks are manufactured as a solid block of concrete or with hollow chambers.
The crack will be a result of that rapid change.
If you notice a stair step crack think of it in the same terms you would a diagonal crack.
Instead your foundation may be expanding and retracting in response to the weather.
Mix the two part epoxy crack sealer.
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.
Explanations for the diagonal or stair step cracks in concrete blocks or bricks near a corner include at least these factors.
Remove all dust and debris.
Although concrete blocks are strong and durable cracks sometimes develop.
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.
Fill in the cracks or holes with concrete.
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.
Vertical movement is being caused by settlement frost or a sink hole or expansive clay soils under and near the foundation wall.
Use a nail to align injection points.
First scrub the crack clean of any loose concrete paint or old filler using a wire brush.
Hairline cracking within concrete block walls is the result of internal stresses resulting from shrinkage creep and thermal expansion and contraction.
Stair step concrete block walls often crack along their block lines.
All of which are anticipated can be predicted and need to be accounted for in design and construction.