Patching crack in steps won’t fix problem

Hey there, time traveller!
This article was published 16/05/2004 (7881 days ago), so information in it may no longer be current.

QUESTION — There is a crack with a width of greater than one-quarter of an inch, or 16 millimetres, in the bottom-most step of the concrete stairs attached to my 47-year-old house. Apparently, the bottom half of the stairs shifted with the ground while the upper steps did not. The stairs are attached to the house, which is built on piles. The last repair was professionally done, more than 10 years ago, and none of the contractors consulted at the time were optimistic that any concrete patch job would last for long. In fact, the crack reappeared two years later and has gotten worse since. The appearance is unsightly and wasps use the crack as an entranceway to their nest beneath the steps.

I understand that cracks in house foundations can be repaired with an injectable, flexible resin that leaves a closed cell rubber gasket in the entire crack. Can this be used for my cracked step? If so, is this an easy do-it-yourself project? Where can such a material be acquired and would its colour match the concrete? If not, what are the alternatives?

Thank you in advance for any assistance you can provide in this matter.

— Ricky Kraut, Winnipeg

ANSWER — There may be several considerations in attempting a repair on a damaged set of concrete steps other than patching the crack itself. If the crack continues to enlarge due to ground movement, the bottom step may be dropping, increasing the rise between this and the next step. This will create a greater chance of tripping on the steps, which may be a significant safety concern.

Repairs to cracks in concrete can often be effectively done using injection with compounds like the one you mentioned or, more commonly, epoxy-based adhesives. These materials will fill the crack and seal it to prevent moisture and pest intrusion. Some may even help to bond the two surfaces together, preventing some movement, but not eliminating it. This may be effective for a short period of time, perhaps up to a few years, but will eventually lose its adhesion to one of the moving surfaces and the crack will again open up. This is what has happened in the past with the other repair.

The cause of the crack must be addressed before attempts at repairs are done, to ensure success. The cause of the crack is movement and settlement in the bottom step, which has broken away from the main stairs, due to soil erosion and seasonal expansion and contraction. There is likely a void developed beneath the steps that the wasps have used to create a nice dry home for their nest. This void may be several feet deep and will allow the soil surrounding the stairs and beneath the bottom step to slowly sink toward this pit. This will cause the bottom step to sink, while the upper part of the stairs remain attached to the foundation of the house with bolts or reinforcing steel. To fix the problem properly, the bottom step will have to be broken up and removed to allow backfilling the void beneath the stairs.

Once this pit and the surrounding soil has been filled and built up to prevent further erosion, the steps can be repaired. Compaction of a good base of granular fill below the old bottom step is essential to prevent further movement. Once this has been done, a new bottom step may be formed and concrete poured to replace the settled one. If the sidewalk or landing in front has sunken significantly, two new steps may be required to retain the proper rise. This new step should be secured to the remaining old concrete with re-bar or steel bolts, installed before re-pouring.

If a new bottom concrete step is not desired, or proves too difficult, a pressure-treated wooden step may be installed with less effort and cost. This could be bolted to the old stairs and would be less likely to pull away with soil expansion and contraction. It will not match the upper stairs, but may provide a simpler solution. Care must be taken to prepare the soil beneath the steps and the new stair similar to the concrete repair suggested previously.

This issue may seem like a small item that may be moderately costly to properly repair, considering the size of the crack. This cost will be minor compared to the damage if someone happens to stumble and fall due to the uneven surfaces between the stairs. In this case, serious injury may occur to family or friends. Patching the crack to keep out nasty stinging insects may be a legitimate concern, but proper repairs to prevent dangerous falls is much more of a reason to do the job right.

Ari Marantz is the owner of Trained Eye Home Inspection Ltd. and the vice-president of the Canadian Association of Home & Property Inspectors (www.cahi.mb.ca). Questions can be e-mailed or sent to: Ask The Inspector, P. O. Box 69021, #110-2025 Corydon Ave., Winnipeg, MB. R3P 2G9. Ari can be reached at (204) 291-5358.

trainedeye@iname.com