Fixing growing crack in slab garage floor

[rarevair]

Last February I purchased a property with a house and a 24'x41' garage with 12' ceilings. The garage was built in 1960 and had a about 1/4-1/2" wide crack running down the length of the garage. There were no expansion joints cut in the floor when it was poured.

I figured 1/2" over 50 years wasn't bad, so I patched the crack and went on with my plans for the shop. Well now it is 6 months later and the crack is growing . . . about an additional 1/4-1/2". It is pretty obvious that one corner of the garage is 1-2" lower than the rest.

Called a foundation guy in and he said he would think about it. His plan is to cut the floor back 12" on each side of the crack, then drill and pin each side with rebar epoxied in, tied together then additional rebar down the length of the crack. There is no sign of rebar or mesh in the original pour. He said he could not lift the corner to make it level, all he could do is stop the crack.

Anyone out there with experience that might be able to tell me if this is a good fix or if there is a better way to fix the problem? The estimate is a little over $4,000 for the work. I am 67 so if the fix lasts for 15-20 years I will be fine.

 

[The Cobbler]

if the crack is widening something is settling . not sure that re bar will help much.

 

[jkeyser14]

Check for overflowing gutters outside, or an improperly sloped yard. If things are shifting it is because the ground is moving around the garage's foundation. Excessive water is usually the #1 cause.

If you repair your slab, chances are that it will crack again quickly unless the underlying issue is addressed.

 

[mm08822]

Yes, I think if there is still movement after 50 years then there is another issue. I agree water is the most likely culprit.

Have you made any changes to the grade around the garage?
Are there gutters collecting and diverting the water away from the foundation?
Are there any cracks in the foundation?

I would hold off on the patch until I was certain it wasnt just a symptom of another problem.

Was the crack filler you put a cement product or a resiliant rubber based product? A rigid crack filler will typically crack or seperate with any thermal changes in the slab.

For now, I suggest you measure the slab elevation in many locations, recording the distance from a rigid reference point(s). Could be 20-30 points. Also measure across the crack and record those distances. Put 2 marks on the floor, say 3" apart spanning the crack. Measure later as well. 10-20 locations.
If the floor is moving based upon these before/after measurements, then no repair from topside is going to stop further movement.

 

[rarevair]

Thanks for the responses. The crack filler I used was a cement product, rigid. Will check for drainage issues. There is a downspout at the low corner. The tube from the downspout to carry water away from the building was off when I took possession of the building. I have since replaced it.

My concern also is that this plan is not fixing the source of the problem and that it may return at the same spot or in a different area. Contractor said he could not guarantee the fix, then after some prodding said he could guarantee it for two years.

Looks like time to get estimates from other local foundation repairmen.

 

[archy99]

As noted...something is settling. Don’t do a repair until you find and fix the cause of the settling. I would expect to start seeing some flexing and pulling in the framing as well, but it might not be noticeable yet. Get a laser and monitor slab and plate elevations from a fixed, stable elevation (through a door or window to another structure, nail in tree trunk, etc). Once you get it fixed, you could even do the slab jack thing to level the slab. Crack should be back to minimal at that point, and you could use a standard joint filler at that time, just to seal it up.


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[Vintage Veloce]

I agree with finding the cause first. But after that, look into foam or mud jacking.