Dear Angie: I just had a new concrete driveway poured, and the very next morning, several cracks showed up. My contractor said that this is normal and will not affect the integrity of the concrete. My contractor had a representative from the material supplier take a look, and he also said that this was normal. I looked at my neighbor's 1-year old driveway, though, and there is not a single crack in it. I elected to hold the final payment until I get a satisfactory answer. What do you think? Is this normal? — James B., Chicago.
Dear James: Unfortun ately, cracking is pretty common in concrete, especially during the first 30 days, while it's curing, or setting up. If a contractor does it right and the conditions are ideal, the cracks can be virtually unnoticeable, except to the homeowner's prudent eye.
There are several reasons concrete cracks. The most common is because concrete shrinks as the excess water evaporates and it hardens. Unfortunately, too often, contractors add too much water to the mix, because it's easier to apply, but that makes it more vulnerable to cracking. Concrete also can crack if it dries too quickly.
Weather conditions — extreme temperatures, rapid temperature changes or conditions that are too wet or too dry — also are major factors in how well concrete cures.
Another consideration is if the contractor used control joints and spaced them properly. Contractors place control joints in the concrete with the anticipation that it will crack. Also called "relief joints," control joints are the straight lines or grooves you typically see at regular intervals on concrete sidewalks, driveways and garages. Their purpose is to relieve the pressure that leads to cracking, with the cracks essentially forming in those grooves, so that, cosmetically, it's barely discernible.
I recommend that you give it a little more time. Concrete takes a good month or so to really set up. By then, the cracks could be undetectable.
The method the contractor uses to cure the concrete plays a big role on how well it holds up. Concrete requires a moist, controlled environment to gain strength and harden fully. Talk to your contractor about his method to cure the concrete.
It expands and contracts in response to the temperature. Fluctuations in the weather during and immediately after the pour, and that is known to happen in Chicago, can create problems. Contractors must be good judges of those situations to determine when to seal the concrete to reduce the chances of it cracking.
Those many variables alone could have played a factor in why your neighbor's driveway has no visible cracks.
All that said, if after it cures the cracking is severe — big enough that you can fit a quarter in the crack — that's an indication of a problem and deserves a conversation with your contractor about an agreeable solution.
You were smart to withhold the last payment. That's something I advise homeowners to do precisely for cases like yours. You now have leverage in case those cracks do become worse instead of better.
If you continue to have concerns about the integrity of the concrete, consider bringing in an independent home inspector or structural engineer to determine whether there's a more serious issue.