Cause for broken concrete blocks.

[jay156]

Hey, I looked at an out-building and a garage for a client yesterday, and came across what's in the attached photo. This is an exterior wall for an attached garage with a bedroom above. It appears that the sill plate is twisted downward towards the middle and the concrete blocks supporting the wall are cracked at floor level and have deflected inward at their tops.

I was unsure of what could have caused such a failure. My best guess is that at some point in the past, someone overloaded that wall and crushed the inside face of the blocks, which must not be sufficiently reinforced. The garage floor kept the whole thing from collapsing inward, but the top course of blocks are all messed up.

Any ideas on what caused this?

Thanks.

 

[a2mfk]

Its not clear to me the structural system ie wall section:
CMU stem wall foundation that extends above the floor slab and then stops, providing a bearing surface for a wood framed wall? Or is this a monolithic foundation with a concrete stem wall?

Some more pictures may help, I can't tell what's going on from that one. Maybe a sketch of the wall cross section with some arrows to show how you think the wall has moved?

 

[jay156]

I'm pretty sure the wall is just an ordinary stud wall. I couldn't tell either what type of foundation he had. I assumed it was CMU, but I suppose the upper portion of it may have been different than what's below grade.

 

[cdhse]

That photo is really hard to see what you are describing. Could it be freeze and thaw of moisture in the blocks? Have the blocks been saturated for long periods of time? In my area I have seen shells of block erode from both things above. I would think if the loading was so severe the shell crushed, there would have been damage to the sill plate in compression perpendicular to grain.

 

[a2mfk]

You need to go back out and take your shovel and figure out what kind of foundation it is, and look closer at the base of that wall. Bring a hammer and do some tapping, figure out if its solid grouted CMU stem wall or concrete or... Not sure you can figure out what has occurred with a structure if you don't know what the structure is exactly.

 

[jay156]

I don't believe there has been water sitting against the wall, though the house is 50 years old, so at some point there may have been. The sill plate looks like it's tilted downward under the wall. Could it have been an automobile impact? Or maybe a heavy truck parked too close? (It's a side wall of the garage).

I attached a section showing what I think it looks like.

 

[ishvaaag]

Maybe it is the soil has swelled outside generating forces not compensated till such movement has occurred. Water in the soil may have congealed outside and pushed inwards. It might also be that the building box above has elongated on high temperatures and the soil has not been able to follow, but seeing the aspect of the worrying point and the localized variation seems as if water has had a say.

In general it looks like relative horizontal slippage of the building atop on the foundation; and not vertical (except if the wall has been repaired) from tilt under lateral forces.