wall cracks (photo)? 2

[greznik91]

Hi,

This is residental building (60 years old) - what is (most likely) the cause for cracks in the middle of the wall (bellow the window)?
- settelments in the middle of buidling?
- insufficient foundations?

Cracks are 3 - 5 mm wide
Cracks are 10 years old but they are getting wider.

How bad is this and what is the best thing to do here?

thank you for reply.

regards.

 

[phamENG]

Looks thermal to me. I would doubt that it's caused by settlement. Odd spot for that to happen. If it is, the middle of the house would have to be sinking. And you'd see an obvious variation in the crack width - wide at the bottom to smaller at the top. Along with some signs of bending stresses in the window frame and further cracking above, probably from the top corners of the window.

These look pretty uniform in width. Little to no vertical displacement. Is it a CMU substrate? If so, it may have happened a long time ago, but took a while to telegraph through to the plaster.

The "they're getting bigger" argument is hard to go on. You need better data. If it's a significant concern, install crack monitors and read them periodically. Also track weather (rain/drought cycles, temperature cycles) and plot them against one another. One of my favorite house crack jobs was one where I got a call after 3 or 4 weeks of no rain (rare here), but I couldn't get out there for a couple days. In those 2 days we got nearly 10 inches of rain. When I got there, the cracks were closed.

 

[EngineeringEric]

unless you put a crack gauge on it, don't ever trust 'its getting larger' in my opinion. your crack looks like it is 1/16" or less, its hard to see a 1/64" growth over 10 year period

I don't see any sister cracking in your marked elevation, or cracking above the windows, and this isn't at a corner of a window at all... my guess based on limited information is thermal or shrinkage and just now reflected through or probably cracked plaster/paint 20+ years ago, noted 10, and hasn't changed much since

 

[charliealphabravo]

No scale but I wouldn't guess the cracks are more than 1 or 2 mm. The spalls are not be part of the crack width measurement since they don't represent lateral movement away from the crack.

Again just arm-chairing, but it looks like longitudinal material shrinkage with stress relief cracking at the weakest/smallest cross-section (middle of wall at window).

 

[oldestguy]

Anything inside that might be contributing, such as wood flooring perpendicular to the wall? Is that shrinking also in winter?