Chris Bernhardt Posted March 28, 2008 Report Share Posted March 28, 2008 I have always wondered how you can get such big ol cracks in stem wall foundations on flat ground as if the foundation is drifting a part? Any explanations? Image Insert: 74.91 KB Image Insert: 88.11 KB Chris, Oregon Link to comment Share on other sites More sharing options...
John Dirks Jr Posted March 28, 2008 Report Share Posted March 28, 2008 It looks like it's wider at the top as if it were a rotational crack. Link to comment Share on other sites More sharing options...
Jim Katen Posted March 28, 2008 Report Share Posted March 28, 2008 Originally posted by Chris Bernhardt I have always wondered how you can get such big ol cracks in stem wall foundations on flat ground as if the foundation is drifting a part? Any explanations? Organic material under the footing. Uncompacted fill. Uncontrolled roof runoff. My daughter driving a car nearby. - Jim Katen, Oregon Link to comment Share on other sites More sharing options...
Phillip Posted March 28, 2008 Report Share Posted March 28, 2008 Here is a large crack in the garage floor that has been patched. Image Insert: 92.94 KB Here is one in the drive way. Image Insert: 104.15 KB Here is one in the drainage beside the drive way. There is a large oak tree here and more in the yard. but this is setting on a small hill at the edge of the drive way to the back yard. Image Insert: 132.14 KB It could be both the tree and the hill slope causing the problem Link to comment Share on other sites More sharing options...
Chris Bernhardt Posted March 28, 2008 Author Report Share Posted March 28, 2008 I know but what I was specifically thinking about those wide cracks on flat grade where there is even substantial separation down to the bottom of the footer. My theory is that those type of cracks occur in two events. The first event is a rotation caused by a load away from the crack resulting in a strictly Vee crack and the second event a load at the crack. The force at the crack would have the tendency to push the bottom of the footer apart. Chris, Oregon Link to comment Share on other sites More sharing options...
Rob Amaral Posted March 30, 2008 Report Share Posted March 30, 2008 Could it be frost-action (seasonally) on a foundation that has a footing not below the local frost line? Was that buiding unheated for a stretch? Unheated buildings with short-depth foundations can ride the frost-train and crack like that. Link to comment Share on other sites More sharing options...
Chris Bernhardt Posted March 30, 2008 Author Report Share Posted March 30, 2008 Could it be frost-action (seasonally) on a foundation that has a footing not below the local frost line? Was that buiding unheated for a stretch? Unheated buildings with short-depth foundations can ride the frost-train and crack like that. Thats a good point Rob. I don't usually consider that around these parts. Chris, Oregon Link to comment Share on other sites More sharing options...
hausdok Posted March 30, 2008 Report Share Posted March 30, 2008 Hi Chris, I don't know about down there, but up here when it has spread apart like that I usually assume that it has probably moved as the result of some seismic activity. Of course, most of what I see is placed concrete. I rarely see CMU foundations; so, I suppose if I saw them often I might have a different view. ONE TEAM - ONE FIGHT!!! Mike Link to comment Share on other sites More sharing options...
Chris Bernhardt Posted March 30, 2008 Author Report Share Posted March 30, 2008 About 8 years ago inspected a ranch house that had an unreinforced poured concrete crawlspace foundation that had several of these big gapping cracks on the order of one inch. The house was on a level lot but it was suffering from a wet crawlspace. The only thing I could imagine was wet unstable soil under the foundation and then high winds to make it see saw apart. Chris, Oregon Link to comment Share on other sites More sharing options...
Jim Katen Posted March 30, 2008 Report Share Posted March 30, 2008 Originally posted by Chris Bernhardt About 8 years ago inspected a ranch house that had an unreinforced poured concrete crawlspace foundation that had several of these big gapping cracks on the order of one inch. The house was on a level lot but it was suffering from a wet crawlspace. The only thing I could imagine was wet unstable soil under the foundation and then high winds to make it see saw apart. Chris, Oregon I doubt that the high winds would be necessary. The pumping action of expanding and contracting clay could do it all by itself. - Jim Katen, Oregon Link to comment Share on other sites More sharing options...
Chad Fabry Posted March 30, 2008 Report Share Posted March 30, 2008 Looks like a footing that was installed on a combination of bad fill on one side and virgin soil on the other: a transition lot Link to comment Share on other sites More sharing options...
mridgeelk Posted March 31, 2008 Report Share Posted March 31, 2008 What Jim says, I believe, is correct especially if the cracks are not vertical. The consistency of the width of some cracks in unreinforced concrete may be caused be the "surge" of expansion as water migrates under a structure, especially if the water does not always come from the same direction or source (surface/subsurface). The transitions in the soils in our area can be from expansive clays/shales to stable soils to collapsible silts at the same site. Originally posted by Chad Fabry Looks like a footing that was installed on a combination of bad fill on one side and virgin soil on the other: a transition lot Link to comment Share on other sites More sharing options...
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