Outside concrete crack

Bryan D
by Bryan D
This crack is only 1/8" or less thick. The top of the picture is at the edge of the house by the foundation (slab on grade) and ends at a the edge of the walkway. It is not high enough to trip on yet. What is the best way to fix this? Thanks for any info.
  3 answers
  • First off notice that the crack comes from the corner to the wall. The right angel is the weakest point on the slab. Ideally a control joint should have been placed from the corner to prevent this from occurring. Cracks are caused by settlement. Often the soils next to the house have not been compacted tight enough and as time goes on the soil settles allowing the cement to drop. If you look carefully you may see the original cement line that is along the foundation wall, showing you exactly where the cement was poured before it dropped down. Ideally the best way to fix is to remove and replace. But for now you can help slow the movement by preventing water from getting behind the cement causing additional settlement to occur. As the cement drops water gets behind and below and causes the soil to settle faster, thus causing the cement to drop even faster. So hose out and clean out any loose cement or dust soils that may be trapped between each crack side and along the house. Then using a good quality silicone caulk, gray is color of choice and fill the crack and space between the house and the walk. The crack is not large enough to fill with cement, and even if you could, it would not prevent water from getting behind and causing the patch to fail. If it is unsightly, paint the patio/walk to hide the repair. eventually the crack will continue to open and settle. and you will need to replace. But preventing water to get below will slow the movement down.
  • Bryan D Bryan D on Mar 12, 2013
    Thanks. I was thinking of doing that but was not sure it that would help. Again thanks for the info.
  • KMS Woodworks KMS Woodworks on Mar 13, 2013
    If you have access to an air compressor and a hose with a nozzle I would go this route rather than adding more water. A thin putty knife or old screw driver could also help clean out the cracks. No sense adding water to a water induced problem. Once all of the debris is out you will not need to wait for it to dry. wear some safety glasses or goggles the air will send small bits of sand + dirt flying.