Are cracks on exterior walls serious and can I fix them myself?

Question

I recently noticed some mostly-vertical cracks present on some exterior walls.

In case it is relevant, this is a South Florida home built in the mid 50s. The downstairs walls are CBS (Concrete Block Structure) and the upstairs bedroom/bathroom walls are wood frame.

EDIT: Added images. Sorry for the quality (camera phone).

Downstairs:
East wall (front): Crack that starts about 3 feet from the ground and is about 6 feet long. The crack itself is about 1mm wide. I am not sure how deep is is. There are some spots where there's a little bit of the wall chipping off, but the chips are not deep and are maybe 2mm wide on either side of the main crack.

This part of the house was added on a while before we bought it as an expansion. The crack seems to have surfaced in close proximity to where the old wall would have ended.

East front

East front (closer)

East wall (rear): Crack starting in the corner of a window and working its way down about 3 feet. Same thickness as east wall (front) crack. Nothing chipping off yet.

East rear

Rear wall: Crack same as East wall (front) description.

Rear wall

West wall: Tiny cracks... thinner than the others I mentioned and not even a foot long, but there are 3-4 of them joining together.

Upstairs: Larger crack (between 1mm-2mm) starting at the corner of one window, going down about 3 feet and halfway across to the other window corner. The other window corner has its own crack starting there which works its way down about 3 feet as well, but doesn't join with the other crack.

My neighbor tells me that a few months before we bought the house, the upstairs window was actually a sliding glass door (yes, a sliding glass door to nowhere) and was replaced with a regular window. This crack has me most concerned.

Upstairs

Those are the major cracks I've noticed. I'm hoping to find out two things:

1. How serious is this? I mean, really, is my house falling apart?

2. Is this something for which I can perform a quality repair job (if so, how) or should I seek a professional?

Answer 1

From the pictures it looks like the cracks may only be in the stucco, and the underlying structural wall may be unaffected. It's hard to tell without actually inspecting the wall, but my guess is that these cracks are only skin deep. However, you will want to treat them to prevent them from spreading.

Here is a good article about Cracks in stucco.

Here are some excerpts from the article.

All buildings are subjected to a variety of stresses in various forms and this stress is often transferred to the plaster stucco membrane.

Stucco is not and never was intended to be a structural material.

Cement stucco is a relatively thin, brittle shell over a framed structure and can crack if the stresses are transferred and overcome the strength of the plaster membrane.

SHRINKAGE STRESS

All Portland cement shrinks as it cures. Controlling and minimizing that shrinkage is critical to minimizing cracks

Shrinkage cracking tends to have a map-like cracking pattern.

OUTSIDE SOURCES

Structural loads, lateral force racking, thermal changes, wind, lumber shrinkage and seismic events are all examples of outside sources of stress.

HOW HARMFUL IS A HAIRLINE CRACK?

a hairline crack does not automatically mean the stucco is faulty, failing or will not function for the service life of the building.

MAKING REPAIRS

Once the decision is made to make repairs, there are several options.

Option 1: Treat the joint with the same finish material.

Option 2: Paint the wall or ceiling after treating the crack with an acrylic paint or paint designed for stucco.

Option 3: An elastomeric paint coating.

Option 4: Recoat the wall from architectural break to architectural break with the same finish material.

Option 5: A new basecoat and mesh over the wall area.

Answer 2

I also would like to see some pics. Small cracks in the mortar of Block walls is not uncommon, however the placement of the cracks is a very important clue as to whether or not it is a structural concern. In general, anytime I see a crack starting from the bottom corner of a window and preceding down diagonally, I am concerned. The other crack that may be at the joint of a new addition to the old structure is also concerning. I always accurately measure the distance between the actual blocks to determine if the crack is simply mortar aging or if there is actually a shift in position of the blocks or bricks. Don't panic, some stress or settling cracks after 60 years is not uncommon. The key is to keep water and vermin out of the cracks and closely monitor these areas for any more movement. Obviously, as a contractor, I'd encourage you to seek a professional opinion. (job security...lol) Short of having the cracks re-pointed professionally, there are sealants specifically designed for masonry that can be applied with a caulking gun. Filling these cracks with such a product will not cure the root cause or stop any future settling, but it will keep water out and possibly slow any other water related problems. I'll wait to see your pics, should tell more of the story.

Answer 3

I'd just add that the important thing with cracks is to monitor them over a period to see if and by how much they are growing. Both length wise and width wise.

Small cracks that don't get any bigger are less of a concern than large cracks or cracks that are growing at a "visible" rate.

You could mark the current ends of the cracks and then check back in a couple of weeks to see if they've grown. Also marking across a crack and then measuring the distance between the sides will tell you whether they are getting wider.

If there is rapid change in the cracks then this means that the house is currently and actively moving and getting to the root cause becomes more urgent. If the cracks aren't growing then you can approach the job at a more leisurely pace. It also indicates that the problem may be just on the rendering rather than being a deeper more serious structural issue.

From your pictures the only crack I'd be immediately concerned about is the one in the last picture. I'd still want to get them all checked out though.

Answer 4

Your last picture is definitely more concerning than the others as it appears to be going through the entire wall, however it still might not be any major cause for concern if there is no noticeable expansion over a period of time.

Cracks in walls are most worrying if they can be clearly shown to have a large amount of separation between the two sides. Minor cracks or surface cracks are not typically of major concern to the structure though. With some obvious caveats.

If you have any cracks that show a reasonable difference on both sides for north south direction, ie one side appears to be lower than the other side then it might be more concerning as it would indicate that there has been a drop or lift in either side. However settling could be a reason and also not a major concern.

It is always recommended though if you are seeing a lot of cracks that you get a building surveyor to inspect them and make any recommendations.