Cracks at Top of CMU Wall 2

[DHKpeWI]

I have a question about cracks in a residential CMU basement wall in Wisconsin.

Most of the cracks are in the mortar joints at the top course. The top course of the wall is exposed with no soil bearing up against it. The wall is a non-load bearing, and the top of the wall is not tied into the floor diaphragm. There is a steel beam bearing on a pilaster on this same wall. The clear height of the wall is approximately 7’-0”. There is also a small step crack in this wall.

Since the top of the wall is not braced, I would expect the cracks to be located near the bottom of the wall. What would be causing the cracks in the top course?
Thanks

 

[BAretired]

The soil properties are of interest, but you really must know how the wall is supported and how it is reinforced. DHKpeWI stated:

Since the top of the wall is not braced, I would expect the cracks to be located near the bottom of the wall. What would be causing the cracks in the top course?

That implies a cantilever retaining wall which seems unlikely with concrete block retaining 6' of soil.

Probably the simplest remedy is to assume the existing wall is inadequate and to brace it on the inside with new wood studs spanning from floor to floor.

BA

 

[joeHSE]

I had a wall just like this earlier this year, except the cracking had progressed to 3/4" in some locations. I recommended that they demo and rebuild the wall and provided details for that.

a2mfk: I'll bet dollars to dirt that the wall isn't reinforced or even grouted. I definately agree soils do need to be checked unless DHK is familiar with the soils in that area.

The pilaster and the framing are providing some restraint for the wall and the horizontal crack after the top course is typical...I assume that the house is sided. A lot of times when the contractor switches block size from 8 to 4 for a brick ledge that is where the horizontal cracking occurs.

I think there is some settlement going on along with some lateral pressure. I like BA's suggestion of bracing the wall floor-to-floor with studs if its not too far out of plumb. Get some good solid blocking bwtn the floor joists. I'm not sure what to think about the lack of a sill plate...what does the endwall sit on?...the rim joist probably.