Deep cracks in garage slab


Old 03-13-14, 02:43 PM
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Deep cracks in garage slab

I have a detached 2.5 stall garage with a concrete slab that has a wide and deep crack running from the front to back of garage. The garage is only about 12 years old. I bought the house about 6 months ago and the inspector said to just patch it up, but I don't think anyone realized how deep it really was.

The crack runs almost exactly down the 0.5 part of the 2.5 stall garage (if that makes sense) and that part of the slab is starting to settle unevenly, ever so slightly. The rest of the garage is crack free and 100% level, but I am worried that said part of the garage is going to continue to settle.

The crack is about 1" wide and 4.5" deep at it's most extreme points, and as little as 0.25" wide and deep at its best spots.

I am pretty sure I know why this is happening. The past owner didn't have gutters on the garage and I have noticed as our snow melts (Minnesota) that water is pooling along this side of the garage, and I would imagine this has eroded the ground below the slab on this part of the garage. I have noticed water pooling in parts of the crack. I am putting gutters up ASAP this spring.

I am simply looking for advice on what I should/shouldnt do to remedy this.
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Old 03-13-14, 03:05 PM
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If it was me, I would first divert that water with gutters as you have mentioned. Then when the weather gets warmer I would chisel out that crack to a clean and deep gap. Then fill it with a patch. Until you know that the gutter diversion of water will solve the problem I would not go to any more expense. Its a wait and see situation.
Old 03-14-14, 08:34 AM
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I wonder where some of these home inspectors get their certifications, In a Cracker Jack Box! That crack should not have gone unnoticed and should have thrown up red flags! There was frost heaving caused by poor drainage that cause to concrete to raise and separate. Gutters and drainage around the outside of the wall will be a start. It may help to see what type of drainage is under the slab.
Old 03-15-14, 08:24 PM
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For concrete cracks to open up that wide, there must either be a lot of shrinkage taking place in the concrete (it happens, often related to excess mix water in the original placement), or possibly some lateral subsidence is taking place. In your case, the close-up pix indicate that the initial water content was way too high. Another factor would be a lack of any control or construction joints--a 2.5 car garage slab should have at least a sawn or grooved joint every 10' in all directions. If the slab is lacking enough joints, don't be surprised if the crack patching suggested by others reappears after a short period of time.
Old 03-17-14, 01:06 AM
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after 12 yrs, hope all shrinkage's done,,, too wet a mix & it would feel sandy + you'd have tire ruts by now,,, there are tests for too much wtr but spending $ 750-$1,000 to find out wouldn't be tops on my ' to do ' list,,, suspect a lack of proper jointing w/maybe just a touch of expansive soils underneath melded w/some improper exterior drainage - in short, yours looks a lot like mine whoever put in our 2 1/2 car garage forgot to saw/form/groove jnts + it slopes to the inside idiots !

i'd throw a 4' level or 8' straight edge on the floor & find out how much its out of whack 1st then grind it flat ( either rent a conc grinder OR [ better yet ] hire a pro to flatten it,,, after that, saw full depth jnts & properly seal them,,, THEN you fix the crack,,, IF you're looking for typical diy cheap & quik, put in some foam rope [ backer rod ] & seal w/crack sealant - NOT CAULK OR ANYTHING RIGID ! tool it properly, too
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