How to Fix Sinking Sidewalks in Chicago


How to Fix Sinking Sidewalks in Chicago

According to the U.S. Census, there are over 1,000,000 housing units in Chicago.  Almost every private home in Chicago has a sidewalk; there are sidewalks to the front entry, rear service walks to get to the building from the alley and let’s not forget the infamous “gangway” that runs between the typical bungalow, greystone and 3-flat.  Any way you measure it, there are a lot of sidewalks in Chicago.

The issue with sidewalks in Chicago is they tend to sink and settle due to the clay soils and harsh winters we have here.  You can walk up and down any Chicago street and encounter a sidewalk that leans towards the building, funneling water to the foundation, creating a tripping hazard or just looking unsightly.

There really are only two ways to fix sinking sidewalks in Chicago.  The first, and probably most well known is to just replace the sidewalk.  The second, is to use polyurethane concrete raising to lift the sinking concrete sidewalk.

Fixing Sinking Sidewalks in Chicago

While replacing a sinking sidewalk in Chicago seems like the best or easiest way to approach this problem, lets take a look at what is involved.

First the sidewalk has to be removed.  In the city of Chicago, access is an issue a lot of the time, especially with gangways.  This typically will require breaking up the concrete by hand with sledgehammers or with pneumatic jack hammers powered by a large air compressor.  In either case, this is a messy, dirty and loud proposition.  Not to mention that in the case of the gangway, it is the only route from the front of your home to the backyard without going around the entire block or through a neighbors yard.

Once the sidewalk is removed, the substrate has to be dug out and corrected.  The biggest reason why sidewalks sink in Chicago is due to poor preparation of the ground underneath the concrete.  In order to correct this substrate issue, a minimum 4 inch thick layer of compacted stone needs to be created for the concrete to be poured on top of.  This bed of compacted stone gives the concrete stable material to sit upon.  If the issue beneath the concrete is not addressed, the sinking will occur again and the process was all for naught.

After substrate is corrected, forms need to be placed.  This process is what creates the actual shape and pitch for the sidewalk.  If the sidewalk is in a grassy area, damage to the lawn from the wood or steel forms and stakes used to hold the forms in place is inevitable so the landscaping would have to be repaired after these were removed.

Now the concrete can be poured back in place.  This typically involves a ready mix truck parked in front of your home or in the alley, blocking traffic until all the concrete is unloaded from the truck.  Once the concrete is in the forms, it is then troweled and broom finished.  This step is not the end of the line however, as the concrete has to cure for 24 hours before the forms can be removed and the sidewalk can be put back into use.

Over all the process of properly replacing a sinking  sidewalk in Chicago can take 1-5 days depending on the size of the sidewalk being replaced., The drawbacks to this method?  Cost, the disruption to the property as landscape repair is almost always required and the duration of time that you will not have use of the area.

Sometimes a full replacement is the only option as if the concrete is badly broken or spalled.  But if the concrete is in good shape, there is a better, less invasive more cost effective method to fix sinking concrete in Chicago…say hello to Polyurethane Concrete Raising.

This modern method of fixing settled concrete slabs is cost effective, quick and less invasive than a full replacement.  The settled concrete is repaired by injecting material under the slabs to lift it back into place.  Sounds complicated but the process is rather simple. 

First 5/8 inch diameter holes are drilled in the surface of the sidewalk, about the size of a dime. Once the holes are drilled, plastic ports are inserted into the holes and specialized equipment sitting in a small box truck is used to inject an expanding polyurethane structural foam through the ports under the concrete.  This foam travels under the concrete, filling all the voids that caused the concrete to sink and slowly lifts the settled concrete

Once the concrete is restored to the proper elevation, the ports are removed and the holes are patched.  The sidewalk can be immediately put back into service, no need for downtime of multiple days to do the repair. 

Polyurethane concrete raising on average costs about 50% of what it would cost to replace the same sidewalk.  If the concrete is stamped, stained or exposed aggregate, this number is closer to 25% as these decorative concrete applications are very expensive to replace.  Another point worth mentioning is that with polyurethane concrete raising, you know what the concrete is going to look like when the job is done.  Meaning that the existing concrete is what you know already, new concrete will not match the existing concrete, the quality of the finish can be an issue, and as we all know, concrete will crack but you don’t know where and when.  Raising your existing concrete will give you a look you are already familiar with.

In summary, if you have a sinking concrete sidewalk, patio or driveway, and it is in good condition, the best way to fix it is with polyurethane concrete raising.

If you have a sinking sidewalk in Chicago and need help deciding the best course of action, please contact us.  Here at U.S. Waterproofing we have almost 60 years of expertise in helping homeowners decide the best repairs for their home.


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