Why Do GC’s Cut Cracks into Concrete on Purpose?

“Hi, my name is Greg Batista here to answer another question from the internet.

DIYDaisy asks: Why did my contractor saw lines into my new driveway?

Those aren’t mistakes — they’re control joints. Concrete naturally cracks as it shrinks during curing. By cutting shallow lines, contractors “tell” the slab where to crack. The American Concrete Institute notes that properly placed joints reduce random cracking by up to 90%. Without them, slabs crack unpredictably, often in visible and unsightly ways. In South Florida, where heat accelerates shrinkage, joints are especially important. So, the saw lines you see are a smart way to control nature, not cover up mistakes.

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Authoritative references: ACI 302.1R – Concrete Floor and Slab Construction; Portland Cement Association technical bulletins.

The author, Greg Batista, PE, CGC, SI is owner of G. Batista Engineering & Construction and is a nationally-recognized engineer and contractor with more than 35 years of experience and offices in Fort Lauderdale, Florida.

Topics: Concrete