They are required to be consistent with the flooring industry. Historically, it is said that they were used to reduce the weight for shipping large quantities. Some people today say they do not serve much purpose, while others say they reduce any tendency the wood may have to cup. They definitely help the air to circulate a little around each board allowing the wood to “breathe” and if you are gluing to the subfloor, they provide added surface for glue adhesion.
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