Concrete Overlay Over Existing Garage Slab

daft_GC

Hi folks, long time lurker.

About to start a complete 600 sq. ft garage remodel and the customer would like a new concrete floor. Unfortunately the footings and slab were a monolithic pour so chipping out the existing slab and replacing it is a no go.
The existing slab is actually in decent shape for the age, it's just uneven, has no insulation and ugly. No frost heaving or major cracks.
There is more than enough room for a 3" overlay pour.
The problem is I am getting crazy quotes from subs for the job. Like 10$ a sq.foot for floor prep, insultarp, and the 3" overlay. I figured it would be about 5-6 yards of concrete for the job max.
I'm kind of ignorant to concrete work, but am I right to assume that these quotes are high?
And also do you guys see any issue with the overlay plan?

Thomas

WarnerConstInc.

Like a decorative overlay?

If so, seems in the range, there is a lot involved in an overlay like that.

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genecarp

Daft, welcome to CT, go to the introductions page, tell the guys a little about yourself and your proffessional experiance, also complete your profile, thanks, GMOD.

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scrapecc

4" slab steel reinforced should do the trick. Possibly use a bond breaker also.

WarnerConstInc.

Another one post wonder??

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scrapecc

I do have to sympathize with them sometimes. When I first got on a forum I didn't understand how they worked. And I didn't introduce myself right away either.

TERM101

Around here something like that would go for around $3500

JustaFramer

Why use bondbreaker? I would think that the stab should be attached to the existing with dowel's and the use of glue.

gene dean

You could put a hybrid polymer overlay over the existing concrete. Remove all loose surface material. Prep down to clean concrete and depending on product used, go by the recommended application proceedures. Of course this wouldn't give you any insulation. If you need to level out the slab and add insul board, then thats another thing. I am assuming this area would be heated so really no need to worry about expansion/contraction due to temp changes. If doing a pour over the top to level out, you could go either way on bonded/unbonded theory.

Depending on where you are located will dictate costs. Midwest area, 1/16"-1/4" thin overlays go for around $4-8.00 sq. foot. 2-3" over pour would run around $6.00 sq. foot. 6.5 bag mix, pea gravel, mid range water reducer with fiber. Low water slump to help control hydration cracking. Early entry saw cuts for crack control and your good to go.

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Architectural Concrete Finishes
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scrapecc

It depends on the floor your doing the overlay on, I wouldn't glue or dowl a overlay to a floor that may move. If the floor is in good shape structurally then a thin bonded overlay is ok. but if the floor is cracked and uneven I wouldn't do anything other than a reinforced slab and would want to use a bond breaker to ensure if the floor underneath sinks just a little bit it won't pull on the floor.

gene dean

If the slab is belly up you can do a perimeter saw cut with a walk behind and remove it. Not that big of a deal. I'd step in from the walls a good 8"to 12" and make your cuts. You may still run into the thickened perimeter edge of the monolithic pour but a jack hammer will take care of it.

If changing the elevation from the existing slab you will have to overlay the edges to bring it up to the new pour.

Concrete contractors attempt to keep the transition as clean as possible from slab to footing because of the access of concrete used if the transition bellows out too wide. So the step in to cut the slab should get you pretty close the the original thickness of the slab.

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Elite Crete of Indiana
Architectural Concrete Finishes
Info@elitecreteindiana.com