Nervous about extending concrete slab.


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Old 06-09-13, 12:21 PM
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Nervous about extending concrete slab.

HI, we live in Austin, Texas. We have a 20 year old home with a concrete slab in the back. The slab has an ugly slate tile. We want to extend the slab at the same height and then add some stone over the slab. I have seen some bad slab extensions in the past so I am extremely concerned about having the contractor (not a large company but an individual) do the job. My concerns are the following:
- What happens if the new slab cracks and sinks at the point where the both slabs are connected? How can that be prevented.
- If there is stone (and mortar) over the joint of the two slabs, and the newer slab cracks or sinks lower, wouldn't that show? For example, the mortar crack, and the stone be exposed? I am thinking of the worst case scenario and how to avoid these problems. I also need to know what questions to ask the contractor.

Thanks
 
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Old 06-09-13, 03:40 PM
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The perimeter, or edge you will be extending will have 2' rebar epoxied into holes laterally along your existing pour's edge. The new slab will grasp around these rebar stubs. You should also find out if he plans on using rebar or fence in the pour. How thick will the addition be? Where the two slabs join, should have a control or expansion joint. It will crack, just when and what will it look like. Control the crack and you won't notice it.
 
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Old 06-09-13, 05:18 PM
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Chandler, thanks for your response. The contractor explained that he would add rebar along the existing edge. Then he explained he will place a mesh and pour the concrete over that.

The slab will be around 3 1/2 inches.

I will ask him the other questions you suggested.

The perimeter, or edge you will be extending will have 2' rebar epoxied into holes laterally along your existing pour's edge. The new slab will grasp around these rebar stubs. You should also find out if he plans on using rebar or fence in the pour. How thick will the addition be? Where the two slabs join, should have a control or expansion joint. It will crack, just when and what will it look like. Control the crack and you won't notice it.

Read more: http://www.doityourself.com/forum/ne...#ixzz2VlPLco3z
 
 

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