# Need Advice on Filling low spot on Concrete Slab patio.



## DebbieG (May 31, 2008)

Hi,

I have a raised brick patio with a concrete slab outside of a doorwall in my backyard. It is sagging outside the doorwall and slopes so that water pools outside of the door when it rains.  I have recieved a couple of estimates on replacing it or repairing it, but they are not in the budget right now.  I believe that anything and everything was thrown in to fill the void under the slab before it was poured, hence the problem. The sag is about an inch lower. I would like to try to level it in with thinset (or some other recommended matierial), and tile over.  Has anyone had any experience with this idea?  Also, I believe that the fact that concrete is pourous could be an issue.  If so, what material should I do to tackle that problem? (By the way, I am in Michigan, so cold winters and fact that it is not covered and gets a lot of snow is important to know.)
The patio is 14x11....what should we expect the approxamate cost to be to:
A.  replace the slab
B.  Hire a concrete jacker to raise it (please explain this process, as I can't understand how filling from underneath could fix the dip, since concrete isn't going to bend back into place I wouldn't think.

I am trying to find the cheapest way to fix this problem and plan to do it myself, unless I can find a cheap alternative.

Thank you


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## inspectorD (May 31, 2008)

Sounds like you just need to make a decision as to how much you want to spend. Going over the patio is cheaper but may not last as long. 
Having the slab lifted is the route we take on jobs, unless the patio is severly pitted and cracked.
The lift is done all the time. Towns use this method on sidewalks instead of replacement. It is a grout which expands and lifts the slab to where it looks good.
All that is left are 4 holes about 1 inch.


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## DebbieG (May 31, 2008)

InspectorD

Using this lift method....can you give me an idea what I could expect to pay to repair a 14X11 slab ?   Just a round about opinion.
There are some hairline cracks, but nothing major.  I just am not sure how this would look, considering that lifting the whole slab sounds like the same sag would remain, but would just be lifed to drain the other way.  I could see that working on a sidewalk since that is just a small piece that is likely not sagging, but just not level due to being forced up by tree roots or something.  This is an actual sag.
Please let me know what you think.  If I were to take the tile route, would versabond be the best material, or something else?  Do I need to prep the concrete first?

Thanks


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## inspectorD (Jun 1, 2008)

I guess I misunderstood, the lift will not take out the sag in the concrete if it is one large slab.

Your options are, cut the piece you have into 4 pieces and lift it .
Remove the entire slab and start over, or just fill over the top with a leveling concrete to get rid of the sag.
What did they say when someone was out there to give it a look as to what your best option is.


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## yesitsconcrete (Jun 3, 2008)

here in atl, it'b be approx $1,250 to remove & replace that size slab IF conditions're good (carry distance, obstructions, workload etc),,, a polymer-modified o'lay to fill the birdbath might cost $250 in mtls,,, mudjacking (hydraulically raising the slab using mud/grout) is usually quoted starting @ $500,,, i wouldn't cut the slab into 1/4's w/o seeing the crks as they may be full depth & acting as jnts.

need to rethink your budget,,, w/o any knowledge of methods/mtls, suggest you call a pro,,, even my fellow artisans'll be looking for $1,500 (min) to o'lay & solve this problem.


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