Masonry Crack

[H57]

I am working on a project that involves an existing masonry building. The building is a large two story building with a steel framed floor and roof. The original construction had the masonry exposed and part of the project is to cover this with cement board and stucco. My concern is that at several locations the walls have been repaired due to cracks. At these locations the masonry has been routed and sealed. The repairs have not been done recently and there does not appear to be significant movement since the repair.

If I cover this crack my concern is that the movement will cause problems with the new wall covering. As the cracks are not nice and vertical (although they are mostly vertical) how do you address this with the new wall covering?

 

[JLNJ]

The propogation of these cracks is a tough one to predict.

If they are shrinkage related, then once your building is enclosed and the temp and humidity has settled down (and the CMU has had ample time to cure) the crack may not open up much more or at all.

If the crack is due to settlement or deflection then things may be shifting over time and the cracks may open up again no matter how you fill them.

 

[H57]

Given the location of the cracks I think they are shrinkage cracks due to the lack of control joints in the original building.

 

[concretemasonry]

H57 -

From the description, it sounds like the joints were tuckpointed, which is a method to correct a cosmetic situation or to close up cracks (usually shrinkage) that could possibly leak or promoted deterioration.

If the joints were tuckpointed some time ago and there is not movement now, the wall is apparently stable.

Dick

Engineer and international traveler interested in construction techniques, problems and proper design.

 

[csd72]

reinforce the render with expanded metal mesh to minimise the cracking or rebat a metal plate across the cracks.

Those are two options.

But check what the root cause is as it is better to treat the cause than the symptoms.

 

[SLTA]

If you're concerned with current movement, you could always put a strain gauge across the cracks and see if they're still moving. They would need to be left there for a significant amount of time, though, like a few months at least. More than likely, the cracks are indeed due to lack of original expansion joints.

 

[SLTA]

I should add that the gauges I'm talking about would be the visually readable kind, not electronic.