They are under your sidewalk. And could lurk under your driveway. They may even exist under your car at night. You can’t see it. You may not even be able to hear it. But they are there. And with each passing year, it gets worse. When it gets worse, it becomes wider and deeper. What is this thing that would keep you up at night if you knew it was there? It is a void. A void is a large gap or space under your concrete driveway, your sidewalk, your patio and your garage floor.

Concrete Bridge

A void causes a concrete slab to act more as a bridge than a support. This “bridge” is not designed or constructed to act like a bridge. Over time the concrete that is suppose to support cars and people will give way or sink. It does not take a large void to create big problems. Some of the indications that result from your concrete slab now serving as a bridge are visible. Some are not.

How do you know if you have a void?

Sometimes the signs you have a void are there and sometimes the signs are not as obvious. Garage floors show the least visible sign a void is there. A tell-tale sign if a void is under your garage floor is by hearing it or feeling it. When you drive over a garage void you will hear the shallowness of the space under the floor. You may also feel a slight tremor in the concrete as well. Small cracks may also be visible in the garage floor.

Void under a Driveway

If your driveway has a void underneath it, it will be more obvious. There may be longer and deeperA visible void on the side of the driveway. cracks in your driveway (the longer you wait the deeper and wider these cracks may become), the concrete slabs may be uneven, the concrete by your garage door may appear to have sunken, or the driveway by the street is now sunken or cracking. Or you may even be able to see it on the side of the driveway. (which may not be home to a variety of critters!)

Patio Voids

Your concrete patio shows signs of a void when the steps to your patio have gaps in them larger that ½” Most steps were created to code which is 7 ¾” high. If your steps are larger than this, they may be sinking into a void that is there.

Sidewalk Voids

A void under a concrete sidewalk will be visible as uneven slabs and possibly show cracks in the surface of the slab.

Having voids under a garage floor or a sidewalk can be dangerous. Your car could actually sink into the hole that will be created beneath when the “bridge” gives out. Tripping on an uneven sidewalk could result in anything from a skinned knee to a broken wrist or hip. Not taking care of the voids in a timely manner will definitely be more expensive as the void expands with the years  and it takes more polyurethane lifting foam to fill it.

Use Polyurethane Foam to repair a void

What you can’t see can hurt you. It can hurt your car, your knees and your wallet. Contact  the concrete repair specialists at Concrete Raising Systems today. They use polyurethane foam to lift and raise your concrete garage floors, sidewalks, driveways and patios. Unlike traditional mud, cement and water mud jacking, polyurethane will not sink and it is impervious to the weather. 40% of the jobs we have done followed a job that traditional mud jacking failed to do and when we raise your concrete with foam, it is raised for good!

This article was originally posted in April 2014 and has nee recently updated.