Split up the middle

[Denray]

So I'm looking at this not too old house. There's a crack going up the middle of the driveway and on into the garage.

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Crack goes right on thru the garage.

When I'm in the house the floors slope to the exterior walls, like the hundred year olds.

Under the house the soil has the expansion cracks. Posts down thru the center are tilted, ends of beams curve down. Looks like the perimeter stayed down while the center line swelled up down the entire house.

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Other than that, nice place.

[kurt]

We get those. The outside perimeter of the house is heavy, the interior much lighter, and the whole house pushes down into the dirt like a giant cookie cutter. Here, it's due to the bearing capacity of the dirt and the footings that are usually too small.

Or, you got some strange soil conditions that are heaving the middle up.

Just a couple guesses. Don't know your area, so both may be wrong.

[Denray]

I'm guessing the perimeter footing was down to solid soil and the post and piers are floating on expansive. May be as easy as cutting the posts to fit. For them and a foundation contractor to figure out. No weight diff on the outsides of the driveway.

[kurt]

How far off the San Andreas Fault is the house? Any temblors?.....[:-angel]

[Denray]

We had a good shock a month back. We get little ones, that we can feel, 3x a year. And the occasional blast.

One street may have damage, in a big quake, and the next one over not so bad. Seems like the shock waves spread out like glass cracking. From a yahoo's point of view.

[Jim Baird]

Denny, those posts look stuck on top of a style of spot footing I have seen that looks like a bag of sakrete hosed down in a wheel barrow and bucketed in. The fact that they all lean together makes me think of a terrestrial shrug. I have felt two earthquakes here in GA. In one I was lying on the ground in a tent during a fishing trip. The ground went this way and that, and had the tent been held up by posts, they might have looked like those.

[John Kogel]

Maybe a soil sample would be a good way to eliminate one question.

Roll damp soil into a worm. Clay soil will keep the shape you form it into. Then that could be expansive soil humping the middle.

Sandy soil will fall apart in your hand - the perimeter has sunk, maybe helped along by tremors.

When I have seen cracking like that here, the general consensus is usually poorly compacted fill before the garage was built. But the slanted posts seem to indicate some sideways movement.

[kurt]

Yes, the posts are tilted over like that says something was shaking that box. At least, that's my guess.

I have only one earthquake experience in the Midwest, a pretty good tremble at the New Madrid fault back in '87, that shook all the way to Chicago.