Hair Line Crack in a block wall

[Daniel Vondenhuevel]

I have a block house in Guatemala that has some hair line cracks in the walls. The entire house is made out of block and is a slab on grade construction and the walls are not back filled. The walls were covered with a concrete stucco material and it has developed 2 horizontal cracks that go from one side of the wall to the other. Both cracks are in the middle of the wall. One crack is in the living room and the other is in the bath room. The cracks showed up about a year after the house was completed and over the past year the cracks have stayed the same size. It this something to be worried about or is it just some settling with the new place?

thanks.

[John Kogel]

In general, a crack less than 1/8" wide with no sign of displacement (movement of one side relative to the other), should not be a major concern.
There is likely to have been some settlement as the concrete was curing - normal shrinkage.
However, any horizontal crack can be an indicator of a structural flaw. You won't get a more specific answer without posting more info.
Do you know if the block walls were reinforced? Were the footings poured separately from the slab floor? What is the soil type and how well drained is the grading around the house? Got gutters?

[Lon Henderson]

When I lived in Belize, I frequently found that the quality of the materials could vary wildly. You may have poorly made blocks. And of course, Guatemala is seismically active and a good ground shaking could have caused the cracks. So, I say monitor the cracks, and seal them. Unless they start gapping beyond 1/4" or displacing in some manner, they are unlikely to cause you a problem.

They make a carbon fiber material for repairing masonry walls that reportedly can be very effective. You might check it out.

Carbon Wall repair: Do it yourself repair of wall and foundation walls with the latest carbon-fiber technology (http://carbonwallrepair.com/)

[Daniel Vondenhuevel]

The house was built foundation, then walls and then poured floor. The wall do have some reinforcement but not like they would have in the US. The construction though is different in that the walls have a concrete column every 6'. Soil is a sandy silt with rock in it. The house does not have gutters and has a flat roof but it is graded away from the house. The cracks have not widen in the past year and there was some serous seismic in the area.

I think I will just patch them and see if they get any bigger.

thanks for your help

[John Kogel]

The house was built foundation, then walls and then poured floor. The wall do have some reinforcement but not like they would have in the US. The construction though is different in that the walls have a concrete column every 6'. Soil is a sandy silt with rock in it. The house does not have gutters and has a flat roof but it is graded away from the house. The cracks have not widen in the past year and there was some serous seismic in the area.

I think I will just patch them and see if they get any bigger.

thanks for your help
Thanks Daniel. From what you describe, reasonable construction methods, etc, it sounds minor. After sealing the cracks, if there is an issue, the cracks will reopen - a good way to monitor a crack.

Here's another trick for an interior crack. Crazy glue a piece of glass like a microscope slide across the crack. If there is movement, the glass will break.

[Raymond Wand]

Crazy glue won't work you will require quick setting epoxy if you use glass slides.

There are proper crack monitoring kits available as well.

Avongard | BUILDING FOUNDATION CRACK MONITOR AND KIT | AVONGARD ONLINE PRODUCTS U.S.A. - Mfg# N/A (http://www.professionalequipment.com/building%2Dfoundation%2Dcrack%2Dmonitor%2Dkit/building%2Dfoundation/)

Simple patching isn't always indicative of movement as the patching compounds can dry out/shrink giving the impression the wall has cracked again.

[Garry Sorrells]

Or just glue or screw a ruler to the wall on one side of the crack. Then mark the location on the ruler of the existing crack (both edges) . Write date on ruler of first marking and then successive markings if there is any change. Cheep - simple - effective.