Horizontal hairline crack in stucco

[PowersPE80]

Hello. I was surveying a 3-story, terra cotta building with stucco exterior. The building has plenty of random hairline cracks, apparently due to shrinkage. At the bottom corner of one of the windows there is a horizontal crack, approximately 8'-10' long, located directly at the bottom corner of the window. (See the attached picture). Is this from the stucco shrinking? or the terra cotta shrinking and therefore cracking the stucco? Or a combination of both? There is a similar crack at the window in the same location on the first and second floors. Any thoughts would be greatly appreciated. Thanks.

 

[PowersPE80]

Here is a picture of some of the random hairline cracks. They were already patched up at the time of the site visit. There are plenty of similar cracks that are not patched up. Same question....are the cracks from the stucco shrinking? or the terra cotta backup shrinking?

 

[Ron]

I'm confused by your description of a "terra cotta" building. Is this an old building constructed of structural clay tile?

The stucco appears to be direct-applied to the substrate (no lath). The cracks have been painted over numerous times and look relatively wide, so they are likely reflective cracks from shrinkage of the substrate and of the stucco.

The horizontal crack starting at the window appears to be a reflective crack from a horizontal mortar joint.

Would require more information to be sure of the cracks. A few questions....

1. It appears that the stucco was direct-applied (no lath). Is this correct?
2. How old is the building and the stucco? The windows do not look that old, but could be replacements.
3. Are you sure about the "terra cotta'?
4. It looks like stalactites under one of the windows. Why?
5. How thick is the stucco or is it actually a decorative cementitious coating? (similar to stucco, but very thin)

 

[hokie66]

Stucco is cementitious, thus it shrinks. Clay masonry tends to expand rather than shrink, so if the two are in direct contact, the stucco will crack due to restraint and differential volume change.

 

[mark519]

Ron,
In response to your questions.

1. The stucco is direct applied. There is no lath.
2. The building was built in the late 1920s.
3. The building owner said it was constructed with "large terra cotta glass blocks."
4. They are icicles on the window sills. Not stalactites.
5. It is a decorative cementitious stucco.

The home is located in New Jersey and the owner is convinced the cracks are from Hurricane Sandy. I believe they are due to shrinkage of the stucco and/or clay masonry substrate. But I wanted to provide him with a more specific and detailed response than just saying it's from "shrinkage."

Does reflective cracking refer to the movement of the substrate, and resultant crack of the decorative stucco?

Could pre-existing shrinkage cracks be exacerbated from a storm event?

I've attached one more picture of a stepped crack at the corner. I believe this is the result of foundation settlement near the corner of the building.

 

[mark519]

Ron/hokie,
I realized that I made posts with two different usernames...my old one and a new one. (Different computers had defaulted to different user names).

mark519 = PowersPE80

Sorry for the confusion.

 

[hokie66]

Suggest you use the "contact us" button, and email Site Management to request consolidation.

 

[Ron]

Mark519/PowersPE80....the cracks you have shown are not likely "event" oriented. They are likely a result of generalized movement. The "fresh" cracks (the horizontal crack starting at a window and the mortar reflection cracks) could have been caused by wind events, but not likely. My first thought on the horizontal crack was uplift; however, there are no other indications of such.

The "stair step" cracking shown in your latest photo is not a result of settlement as they are isolated, independent and much higher up the building without continuity to the foundation for settlement issues.

 

[oldrunner]

Your pictures are pretty good. If you enlarge the 1st one, you can see a lot of patterns - probably "historical" cracks that have been painted over - probably a number of times. On the 2nd picture, you can see that the cracks are "dirty" - meaning they've been there a a while. Also can see painted over cracks. New cracks would have "clean" breaks.

In one or two places,it looks like there have been lots of cracking - maybe serious but are now covered with the paint. Do you know what kind of paint is presently on the building?

This could have been a bad stucco job to start with or you have two different kind of substrates. Even though the stucco is over a possible rigid substrate, how is it fastened? Without doing some opening up of the areas, you might not be able to determine this. Is there moisture getting to the interior - with the accompanying mold?

See if you can find some historical photos of the building. Newspaper morgues work pretty good as well as your local historical society. Was the building always covered with stucco? We have a 1853 +/- brick that was covered with stucco in the 1980's, but there are pictures showing showing the same cracks as we see in the stucco on the front, before the stucco was applied.

You may have some soil movement with the seasons - but I think that it would see more serious cracking - but the paint might be stretchable.