Drywall Cracks. What Causes Them?

If you’ve ever examined a piece of drywall you know that it is made up of paper on the front and back with gypsum sandwiched in the middle. Gypsum is a powdery sulfate mineral.  It looks and feels a lot like chalk  kids use to write on the sidewalk. This mineral is brittle with  very little flexibility.  When stressed it cracks and it does not take much to crack it. A 2 x 4 drying out and shrinking or twisting can crack it. Trusses lifting from temperature change can crack a ceiling.   We refer to these as settlement cracks and they are not structural in nature. Remember, it is brittle and won’t flex with even minor movements in the walls and ceilings. Plaster is even more prone to cracking.

Many structural engineers start to get concerned with a crack that is over ¼ of an inch.  Especially, if that crack is uneven in terms of a shift left to right.  The unevenness in the crack shows lateral movement that can be more than just  typically ‘settlement’. Cracks in concrete foundation walls also raise concern.  Hairline cracks in concrete are referred to as ‘shrinkage’ cracks. When the foundation wall is poured it is as big as it will ever be.  As it dries and cures it gets smaller and these cracks occur. Take a look at your sidewalk and driveway – odds are you’ll find these shrinkage cracks.  So, settlement and shrinkage cracks are completely normal and don’t affect your home structurally. If they start to open up or show signs of lateral movement it may be time to have a professional take a look.   

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