Garage slab crack, Southern Cal. Home

[David Nasser]

I inspected a house today and the garage had a crack starting
at the garage door about 2 feet away from the house (its a connected
garage) the crack ran all the way from the 2 door garage to the end of
the slab, the crack was more than a nickels width. Any info on what this
could be ? So Cal is a siesmic area.

I can send pictures an an attachment to your email, but I dont know to add them
here....

David
Nachi member

[Jeffrey R. Pope]

Concrete cracks. There's not much that can be done to prevent it, although there are methods used to minimize cracking.

Much more information would be needed to diagnose a "crack."

[David Nasser]

Im trying to get some pictures of it....they are on my computer and digital
camera, how can I get them to the message board ?

[Jeffrey R. Pope]

Go to the "advanced" reply option and use the "manage attachments" button.

[David Nasser]

its only allowing me 100 kb, for an attachment and
my picture is 376

[David Nasser]

[David Nasser]

http://s187.photobucket.com/albums/x...ent=Pic028.jpg

[Jeffrey R. Pope]

I've seen this exact crack many times

Is the house on a hillside or slope? My guess is "Yes." Is it one or two stories? My guess is "Two."

The house foundation has settled, and this crack is a direct result of that. The crack is not "the" issue, it's just an indicator. If there is no other noticeable damage (to the walls or trusses/rafters), it's just one of those things that should be "monitored" (it will continue to "grow").

Was there other damage to walls and such?

[David Nasser]

I could see a little stress crack on the drywall above the crack of the attached garage.....the house looked ok. I did good structural check
on the house and the attic

[Russel Ray]

That crack is from a recent inspection I did in Fletcher Hills in El Cajon, all one-story hillside homes on landfill. You were there recently, too, huh?

When that type of crack is in the garage and only in the garage, I don't have any problem with it in a structural capacity, especially in an older home. What has happened has happened. However, I have no way during the course of a multi-hour inspection of determining whether the causes of the crack are active or inactive. So it does need to be monitored. Personally, I would also patch and seal it. I told my Clients the same and that if they were uncomfortable or unknowledgeable about such cracks, they could get more information from a geologist, soils specialist, structural engineer, etc. Although there were no indications of excessive settling activity anywhere else in the home, they chose to get a structural engineer out to look at the crack. He gave them a 17-page report of disclaimers with basically a one-line paragraph at the end: "Crack is common to garages in Fletcher Hills and doesn't present any structural concerns at this time. Monitor for change." In other words, "Welcome to Fletcher Hills!"

You say the garage was attached to the home. I've never seen that in any state where I've done real estate work, whether in cold northern areas, hurricane-prone areas, earthquake areas, etc. I suspect that it wasn't. How did you make that determination?

[Richard A. Hetzel]

Is the house also on a slab, or is there a basement or crawl space under the house? If it is all one big slab, it could simply be a shrinkage crack. If there is a basement or crawl space, the gararge slab could be improperly supported on the house foundation, instead of being allowed to "float" within the garage perimeter. Either of those two scenarios could explain the crack, but as a previous person said, there is far too little information to properly diagnose it.

Other questions: is there any vertical or angular displacement from one side of the crack to the other? And this cannot be answered without monitoring, but is the crack stable or is it widening? How old is the garage floor? When did the crack first occur? Was it related to any seismic event when it occurred? Is there any reinforcing or mesh within the garage floor? Are the garage walls all plumb? Is the garage ceiling level? Are there any other signs of distress in the garage?

[Keith Swift, PhD.]

David,
the structural significance of the crack depends on whether the slab is "integral" (load bearing) or "floating." I always give a detailed explanation to my clients and, depending on my assessment of them, give a variety of recommendations. However, I'm not a geo-tech or foundation specialist, so I always make sure that my report covers my assets.