Expert: Dan Griffin - 5/28/2009

Question
Dear Dan: My house is 10 years old. One side of my driveway (the part connecting the garage) has sunk about 1.5 inches. It does not affect my car moving into and out of the garage a lot. Only I need to fix it before selling the house. My question is how can I put a layer of concrete on the small area and make it stay? I am a layman to the concrete work. Can I do it on my own?
Thank you in advance.
Aaron

Answer
Aaron, applying material on top is not the best long term solution to the problem.  It is not unusual for concrete to settle along the building.  The ground was dug up and disturbed to dig the footing and the dirt is shoved back in loose and not compacted.  As it settles and compacts over time it sinks.  Patios, drives, and sidewalks on this material will sink also.

The choices become:

Best, but most expensive = Remove and replace.  

Better = have a "mud jacking" company come and pump grout under the slab to raise it.  They need to drill some holes in the slab that will show and the slab can crack, though some of these guys are really good.

Good - Add enough material to deal with the problem.  The material will probably come loose over time.  It will look like a patch and cure.  It may be difficult to add the material in such a way as to solve the problem.

There are some topping cements that have acrylic binders in them that can be installed outdoors.  Mapei Planipatch and Quickcrete's Vinyl Patch come to mind.  Follow all guidelines on surface prep, water content, and application.  Mapei has some that sets really fast which can be great as long as you are prepared to it.  If this is new to you, you may be best off with a slower setting material.

Call a mud jacking contractor to at least have him look and give you a price and his feelings about success.