Expert: Dan Griffin - 3/25/2010

Question
I have a split level home with concrete stairs from my driveway to front door. This is a new home (not even a year old) and I have noticed there is a void under these stairs. There has been considerable cracking in the driveway (a diagonal crack leading from the stair base to the garage footings that is uneven from one side of the crack to the other) and that there is cracking in our garage footings where it borders the stairs. I am pretty sure the void is the cause of this cracking. I have adequate gutter and there is no drainage that would wash away dirt from under the stairs, so I assume there was improper compaction under the stairs before they were poured.  I have a 1 year warranty on the home and want to know the best way for the contractor to repair the cracking and fix the problem so the cracks don't become hazardous and so that I don't have to re-pour the steps in 10 years when I might want to sell the home.

Answer
Johanna, there are several roots and causes of concrete cracking and uneven settlement.  I suspect the prime culprit was insufficient contraction and/or construction joint cutting or tooling in the original construction.  There are many known precautions and conditions to give cocrete the necessary relief and intentional joints to allow movement.  If there was insufficient compaction it would certainly contribute to the problems and can certainly cause unven settling.  If the cracks are tighter on top than on the bottom would indicate the cocnrete settling, if the cracks are wider at the top than at the bottom, they are caused by pressure, heat expansion, or clay expansion.  The cause is not as important as the solution.

A crack is a crack is a crack.  Cracked concrete cannot be made to look right.  The only possible solutions are "remove and replace" or a special topping that covers all the concrete (These may eventuallly show the original crack).  If you can be satisfied with a workmanlike repair, the crack can be sealed to prevent water penetration.  If the surface is not coplanar which you indicate, the low side can be "mud jacked" but this will require the services of a professional who speciallizes in this.

Have you discussed the issue with your builder?  He will be very reluctant to R&R.  It might be wise to contact a local decortive concrete specialist, even to pay him for a consultation.  Get his professional opinion as to both cause and solution.  I suggest a decorative man as I think he will have more experience than some flat work men.