Need some help with expansion cracks!!!

[SteveL]

I added on to our existing 2+ car garage and the contractor did not put an expansion joint where the new and old floors meet. Yea, it's got a crack that runs the entire length of the floor where they meet and I am planning on epoxying the whole thing soon. Question is....can I use the Rustoleum Epoxy Sheild Concrete Patch and Repair product to fill the crack or will it just crack again with the next season change??? The old floor has epoxy paint on it and I figure that I need to scuff the surface before putting the new coating down, so any filler can be sanded/ground smooth while I'm doing that.

Thanks for the help!!!!

Here's a shot of the addition and if you look close you can see where the new and old floor come together....

 

[bmwpower]

Hard to say. The epoxy patch will eventually succumb to the forces of the concrete. However, if your concrete is done cracking (how old is the concrete?), it would definitely fill the crack.

Is it a straight crack? If so, how about cutting it out and filling it with expansion joint sealant?

 

[SteveL]

Hard to say. The epoxy patch will eventually succumb to the forces of the concrete. However, if your concrete is done cracking (how old is the concrete?), it would definitely fill the crack.

Is it a straight crack? If so, how about cutting it out and filling it with expansion joint sealant?

Sorta straight! The edge of the existing floor was rather rough as it was an outside wall before we added on. The new floor is about 2 yrs old now and I'm sure that is has stopped cracking by now, The crack just follows the natural edge of the existing floor as they poured the new concrete and trowled it flush with the old floor. Sure wished I was here when they did it, but I was out of town at the time. Made me furious when I got home!!! Why are concreete contractors all idiots???

I guess I could rent a concrete saw and cut a new joint, but it seems like I could end up making a bigger mess of it, plus having it flush helps with moving water to the new side which has a drain in the center. Maybe I'll give the repair stuff a shot and see if it cracks over the next month or so before I paint the floor.

 

[bmwpower]

If it's going to crack, it will probably crack when it gets cold outside, ie. when the slab shrinks. I had a couple of cracks in my slab (one year old mind you) and I used the epoxy patch in December right before I coated the floor. No problems...yet.

My experience, too, has been that concrete contractors have some issues to say the least. Hell, I could probably say that about most contractors I've dealt with to date.

 

[SteveL]

Around here, you could get all the work you wanted by just calling someone back!!!!!!

 

[bmwpower]

Around here, you could get all the work you wanted by just calling someone back!!!!!!

I hear you. Same old story...quantity not quality. They're so busy, they don't have to call you back.

 

[Willy Victor]

I added on to our existing 2+ car garage and the contractor did not put an expansion joint where the new and old floors meet. Yea, it's got a crack that runs the entire length of the floor where they meet and I am planning on epoxying the whole thing soon. Question is....can I use the Rustoleum Epoxy Sheild Concrete Patch and Repair product to fill the crack or will it just crack again with the next season change??? The old floor has epoxy paint on it and I figure that I need to scuff the surface before putting the new coating down, so any filler can be sanded/ground smooth while I'm doing that.

Thanks for the help!!!!

Here's a shot of the addition and if you look close you can see where the new and old floor come together....

Nice looking sand blast cabinet Willy

 

[xsponge]

I wouldn't be too hard on the contractor, that is pretty common practice to not put expansion joint in a finnish floor like that. If he had put expansion joint in you would have the same crack only it would be 1/2" thick min. Anyways, it looks as if you heat your garage. that should help as the floor probably dosen't see the extreme changes in temp. It is the extreme temp changes that cause the cracking. Personaly I would cut the crack with a masonary blade down about 1/3rd of the thickness of the slab, then I would fill the crack with some self leveling urathane caulk, put enough in there that it puddles up above the surface of the finnished floor, let it cure, then scrape even with the finnish floor with a painters razor knife, safety scraper type razor. You will have nice expandable seal, that will expand and contract, and will be even with the finnish floor that you can push water over to the new side drain. You could epoxy right up to the joint. You can get the urathane in different colors so you could match or get close to the color of your epoxy.

 

[Charles (in GA)]

I wouldn't be too hard on the contractor, that is pretty common practice to not put expansion joint in a finnish floor like that. If he had put expansion joint in you would have the same crack only it would be 1/2" thick min. Anyways, it looks as if you heat your garage. that should help as the floor probably dosen't see the extreme changes in temp. It is the extreme temp changes that cause the cracking. Personaly I would cut the crack with a masonary blade down about 1/3rd of the thickness of the slab, then I would fill the crack with some self leveling urathane caulk, put enough in there that it puddles up above the surface of the finnished floor, let it cure, then scrape even with the finnish floor with a painters razor knife, safety scraper type razor. You will have nice expandable seal, that will expand and contract, and will be even with the finnish floor that you can push water over to the new side drain. You could epoxy right up to the joint. You can get the urathane in different colors so you could match or get close to the color of your epoxy.

I agree, this is normal practice and I would rather have this than a huge expansion joint.

When my 60x60 slab was done, I did not want it sawed as that is an avenue for ants, or so it seems from other places I've seen. Other problem with sawing is that the cut is never straight.... So I had them key the slab with metal key strips. Worked OK but I have cracks along them. Done right, you use a plastic strip on top of the key, finish the cement and pull out the strip. You get a neat perfect groove about 1/2 wide and about the same deep. Then you fill that with some sort of urthane joint filler and you are done. My contractor did not know about the plastic strips that go on top of the keys, and had never seen them. I did not know till later, I was depending on him. Overall, I'm still OK with the whole job, but something always goes wrong.

Charles

 

[PAToyota]

What I would have specified in such a circumstance would have been to dowel into the existing slab and set 16" lengths of rebar into the holes with epoxy. Then place the new slab. The rebar would have anchored the two slabs together with no cracks. It looks like the slabs are relatively small, so I doubt that you would really need the expansion joint.

 

[xsponge]

Charles & PAToyota, if I understood Steve correctly, the floor is allready poured, and the issue is not that the slabs are uneven or moving. It is too late for keyway or dowels at this point. It appeared to me to be just a matter of a crack where the new slab and the old meet, thus cutting the crack to allow a good application of urathane. This would also seal it up against moisture and insects.

 

[PAToyota]

I understand that what is done is done. Just that if you are going to pour a new slab up against an existing one you pretty much either want to dowel them together or put in an expansion joint - tie them together or give them the ability to move.

At this point, if the crack is not moving I'd do as you say and grind it out a bit so that you can seal it - either with caulk, urethane, whatever.

 

[SteveL]

What would be the best way to grind a valley for the urethane and keep it straight???? Also, can you epoxy over the urethane or do I epoxy first then fill??? I doubt that I can find a color of urethane to match the floor! I would almost rather use the Rustoleum crack filler and paint over it knowing that there may be some new cracks down the road. Thanks for all the input!

 

[SteveL]

Nice looking sand blast cabinet Willy

Thanks! I got it and the compressor and the vacumm for a whopping $500!!! Best deal I've ever run across!

 

[xsponge]

I wouldn't grind a valley, just a saw cut on a chalk line should do it. Buy a couple of Masonary Blades for you skill saw, go about 3/4 to 1" deep should be plenty. You can purchase Urathane any almost any color. I would epoxy first, then cut and urathane. If you are worried about getting the urathane on your epoxy, use 2" masking tape on either side of the crack. Then like I said scrape the urathane flush with the top of floor.