Cracked concrete slab - looking for solutions :)

kateblood · Jun 20, 2010

Hi

I live in Northern California and recently bought a 1951 ranch house with a detached 2 car garage. We have started renovating the garage and when we had a few concrete people come to look at the the slab to repair it and they couldn't run away fast enough... we have a very large crack down the middle of the garage (probably from earthquake) and apparently the way to fix it is to have a structural engineer come in and then lift the whole garage and pour a new reinforced slab. this is not within our budget, so we are looking at a work around to make the garage look good.

the whole garage floor is humped in the middle. we thought we could cut the crack out then fill it with more concrete to make it more even then cover in something like racedeck. I came across this site and thought I would ask for some opinions here. I have attached some photos for you too see.

we are hoping to make it look great for minimal cost.

any ideas?

ZRX61 · Jun 21, 2010

Bust it out & pour a new slab in the garage?

Justanoldguy · Jun 21, 2010

Just pour another 4 inches over the top.

Wingnut65 · Jun 21, 2010

Caulk it?

The stresses in the slab will want to continue until the stresses are removed. If you can't remove the whole slab, at least consider removing about 2-3 feet width the whole length of the crack and pour back new. This would provide a more level surface for RaceDeck to go over.

If a new slab on top is in consideration, make control joints directly over the crack to control where it does crack when it does.

LegacyIndustrial · Jun 21, 2010

In the mean time, me have a gel epoxy crack filler that will make short work of your cracks. It will buy you time. Anything that won't flex will likely crack up and waste your time. Check the link.
http://legacyindustrial.net/cart/crack-sealant-gel-style-p-16.html

-Scotty

rasit · Jun 21, 2010

kateblood said:
Hi
... we have a very large crack down the middle of the garage (probably from earthquake) and apparently the way to fix it is to have a structural engineer come in and then lift the whole garage and pour a new reinforced slab.

Can't tell from the pics but are the walls built directly on the slab? Did they heave/shift? If the walls didn't move maybe you could get away with cutting the existing slab a foot or two in from the walls and pour a new reinforced slab, doweled into whatever remains from the existing slab. If the walls moved there is no easy fix structurally.

kellymc · Jan 10, 2013

Sorry to revive an old thread, but I have the same problem as the original post.

My garage was build on a slab which is now cracked badly in multiple places due to inadequate prep under the slab. The structure is sound and has not shifted at all. The slab is 2-3" thick and the walls are build directly onto the slab.

How can I cut and remove the old slab and pour a new reinforced slab and tie the walls into the new slab?

Kelly

brownbagg · Jan 10, 2013

jackhammer. that a foundation failure not just a stress crack

ConCretin · Jan 10, 2013

Yea, there comes a point where just ripping the thing out makes the most sense. It's not as costly as you'd think and you end up with a shiny new slab.

kellymc · Jan 11, 2013

Unfortunately I'm in California, so I can't rebuild without tons of permits/epa/environmental impact reports. So I'd like to keep the structure and replace the floor, however I don't want the garage to falldown if I cut the old floor out.

DonnyT · Jan 11, 2013

IMHO there is no way to repair that slab without cutting the old cracked cement out. Why would you need EPA impact reports for a new slab??? Start a new thread with your own pictures is also a suggestion I would make. The pictures above are pretty severe.

ddawg16 · Jan 11, 2013

kellymc said:
Unfortunately I'm in California, so I can't rebuild without tons of permits/epa/environmental impact reports. So I'd like to keep the structure and replace the floor, however I don't want the garage to falldown if I cut the old floor out.

Are you sure about that? I think all of my permits was less than $500 for my garage.....and it's 2 story.

Enviromental impact? For a garage....if your replacing what you have....shouldn't be an issue.

If your garage is built the way mine 'was'.....there is no rebar in the floor....the floor is integral to the footing...the footing maybe has 1 #3 bar top and bottom.

Click on the link Garage build link in my signature to get and idea of what I did.....

brownbagg · Jan 12, 2013

Look at the crack, its opening up, a stress cracks going be hairline and not go all the way through. concrete cracks when the slab bends. You can tell because the cracks in the middle, opening up and the ends has a 45 degree to corner that your footers have some major settling. The center of slab subgrade is holding up and that what cause the bending.

its almost seems like there is no footers under the slab. I know there no reinforcement and the slab was poured wet with maybe a psi of 1500-2000.

I would jack the garage and replace footers and slab on a compacted fill with rebar placed in the concrete slab

Kevin54 · Jan 12, 2013

kateblood said:
Hi

I live in Northern California and recently bought a 1951 ranch house with a detached 2 car garage. We have started renovating the garage and when we had a few concrete people come to look at the the slab to repair it and they couldn't run away fast enough... we have a very large crack down the middle of the garage (probably from earthquake) and apparently the way to fix it is to have a structural engineer come in and then lift the whole garage and pour a new reinforced slab. this is not within our budget, so we are looking at a work around to make the garage look good.

the whole garage floor is humped in the middle. we thought we could cut the crack out then fill it with more concrete to make it more even then cover in something like racedeck. I came across this site and thought I would ask for some opinions here. I have attached some photos for you too see.

we are hoping to make it look great for minimal cost.

any ideas?

With the comment you made about jacking the garage up, I am assuming that the garage is sitting on TOP of a slab and no foundation poured or block laid up to support the garage.

If that is the case, I would come in about a foot all around the perimeter of the garage and cut through the slab. It will be a dusty dirty mess, Best to be done on a rainy day so you don't piss off the neighbors,

Bust out everything within the cut lines, Drill some holes in the concrete around the perimeter going in horizontally to the slab to insert some rebar. You would want to pin the new to the old. Without seeing a pic from the outside looking in, hopefully would would be able to pour a 2" cap over the old so you have a nice smooth surface on the inside.

6t7gto · Jan 14, 2013

Kevin54 said:
With the comment you made about jacking the garage up, I am assuming that the garage is sitting on TOP of a slab and no foundation poured or block laid up to support the garage.

If that is the case, I would come in about a foot all around the perimeter of the garage and cut through the slab. It will be a dusty dirty mess, Best to be done on a rainy day so you don't piss off the neighbors,

Bust out everything within the cut lines, Drill some holes in the concrete around the perimeter going in horizontally to the slab to insert some rebar. You would want to pin the new to the old. Without seeing a pic from the outside looking in, hopefully would would be able to pour a 2" cap over the old so you have a nice smooth surface on the inside.

We did this to my dad's garage about 10 years ago. Came out great.
Used a water hose as we cut the concrete and the dust was minimal.
We laid a 2x4 against the walls and followed along with the saw.
david

cj7365 · Jan 14, 2013

yikes, I would have to come up with the money, and replace the slab, it is a complete failure, by filling in the cracks you are just putting a band aid on it, thats why all those concrete guys ran away

Cracked concrete slab - looking for solutions :)

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