Are Cracks in a Basement Normal?
All buildings are subject to seasonal warming and cooling of the temperature, as well as wear and tear over time, not to mention movement in the ground itself. While it is possible to minimize the cracking of concrete, it is normal for concrete to crack over time for a variety of reasons. Not all cracks are detrimental to your basement, and knowing the difference can help save you money on expensive repairs. Does this Spark an idea?
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Shrinkage Cracks
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Shrinkage cracks are one of the most common types of cracks you will find in concrete. These are naturally occurring cracks that happen during the curing and shrinking process of the concrete. As a general rule you can expect concrete to shrink 1/16 inch for every 10 linear feet of concrete, which means a ¼-inch crack in a 40-foot slab is completely normal.
Settlement Cracks
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Settlement cracks are noticeable in areas where there are two different heights of concrete. The differences may be subtle, but they are a result of inadequate site preparation before the pouring of the concrete. All concrete slabs require a packed base of fill material such as gravel, and if the base isn't packed properly the concrete will settle differently in different sections, creating cracks between the two different levels of slab that can potentially grow over time. Unless they are massive cracks (1/2-inch or larger), they pose no threat to the structural integrity of the building, and are natural occurrences with any home.
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Frost-Heave Cracks
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Frost-heave cracks occur when there are two different levels of concrete, much like settlement cracks, but frost heaves occur when water collects in the soil or base material beneath the concrete and freezes. When water freezes it expands, which can force the concrete upwards, forcing cracks as nature performs its natural cycles. Frost heaves are only harmful to the integrity of the concrete when they begin breaking the concrete or causing larger than 1/2-inch cracks.
Cold-Seam Cracks
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Cold-seam cracks are only visible on vertical sections of concrete, such as walls in a basement. They are created during the pouring process when one batch of concrete cures slightly while the next layer of concrete is on its way via truck or mixing machine. The slight difference in cured concrete creates a difference in curing rate, which can cause a crack over time as the concrete cures completely. As long as the wall is sufficiently reinforced with concrete, these are harmless cracks.
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