Plaster Crack or Structural Crack? (Video)

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

CrackDetective asks: How can I tell if a crack is just plaster or something structural?

Great question. Plaster cracks are usually thin and surface-level, caused by drying or small shifts. They’re often harmless. Structural cracks are deeper, wider, and sometimes show rust stains or displacement. The American Concrete Institute recommends evaluating cracks wider than 0.012 inches (0.3 mm), especially in exposed concrete. In South Florida, small cracks can worsen fast because salt and water intrusion accelerate corrosion inside. Warning signs include stair-step patterns in masonry, widening cracks, or cracks that let water through. When in doubt, have a licensed engineer inspect. A quick checkup can prevent costly structural damage down the road.

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Authoritative references: ACI 224R – Control of Cracking in Concrete Structures; Florida Building Code coastal exposure provisions.

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.