Question: I was moving some plants in a front flower bed recently and while digging next to my concrete steps I realized there was about an eight-inch (20-centimetre) void between the base of my steps and the soil beneath. The steps have been re-capped recently but retain what I think is the original base. I know we had some red squirrel issues a few years ago, but haven't seen any recent activity, so I'm not sure they're the reason for the void or if it's just a natural occurrence with settling over a number of years.
Should I be concerned about the steps being unsupported? I don't want to lose the investment of recently repaired stairs. Would it be of any use to try and backfill under the stairs with crushed limestone? And, if the squirrels are the root of the problem, how best to keep them out from under the steps?
Thanks for your time.
Regards, Perry Favoni
Answer:
Filling in voids under steps, overhangs, or other areas around homes is part of typical maintenance. There are a few reasons to keep these areas from becoming problematic, not the least of which is prevention of pests nesting in these areas.
Trying to determine the cause of the void under your front steps may be fruitless, but successfully filling it in will likely leave you pest-free. It would be unusual for red squirrels, which normally make their homes in trees, to build a nest under your steps but other ground squirrels, chipmunks, and rabbits may find the area ideal. Also, bees, wasps, hornets, and other stinging insects like protected, damp locations like that for their hives. Keeping the area filled in, especially with sharp edged stone, will prevent these critters from getting too comfortable under your stairs. While that may seem like the primary reason for your efforts, other considerations may be just as important.
When soil settles or erodes near your foundation, especially under steps, additions, or other overhangs, there is much more chance of water pooling from rain and snow melt. When water pools against a foundation wall, it is only a matter of time before it will find a small crack, hole or defect in the damp proofing to leak through. Because the soil in the void is below the level of the surrounding earth it will tend to collect more than in other areas.
As far as structural concerns with the disappearing soil, that may not be as much of a problem as you might suspect. Most concrete stairs may appear to be solid, but in reality are hollow and relatively thin. If they were constructed of solid concrete they would be so heavy that movement would be a more likely outcome. Also, many stairs appear to be supported by the soil alone, but may have more stable supports at the front and rear. Sometimes, deep concrete piers, or piles will be installed at the front corners of the stair landing to support the entire assembly. Other times, larger concrete footings are poured for the same purpose. Alternatively, many other sets are attached or connected to the foundation of the home to prevent movement. Losing some soil to normal forces of nature should not cause the steps to become unstable.
The next of your questions to address is the proper material to use for filling in the space in question. I often get this question during the course of regular inspections and my reply is that any type of fill that can be easily shovelled or poured into this tight area is acceptable. Soil, sand or smooth stone will fit in this category, but crushed limestone may be the best choice for a couple of reasons. The sharp edges of the stone may make excavation by invading animals more difficult, while it will be relatively easy to shovel into this tight area. It also compacts well, especially if it is quarter or three-quarter down material, which contains stones of various sizes combined with sand and other particles smaller than the screen size it is named after. Those properties, as well as the fact that it will become fairly solid if wetted down, make it an ideal substrate for your purpose.
Preventing moisture from permeating into the foundation of a house should be a primary goal of any homeowner. Filling in any large voids, like that under your front stairs, will go a long way in achieving that goal. An additional bonus will be preventing pests such as rabbits, wasps, or squirrels from taking residence in the protected space. Ensuring that this is taken care of, on a regular basis, will help alleviate these concerns even if structural considerations are not much of an issue.
Ari Marantz is the owner of Trained Eye Home Inspection Ltd. He can be reached at 204-291-5358 or check out his website at trainedeye.ca.
trainedeye@iname.com
