Traditional OSB is a problem for resilient and wood flooring installations because of the nature of its construction. Traditional OSB is made from large chips of wood that will swell when exposed to humidity and moisture, causing the texture of the chip structure to show through on resilient floors. According to the Engineered Wood Association, OSB is only suitable as a substrate for stretch-in carpet, which isolates the texture of the OSB from the flooring with a layer of carpet pad. The association goes on to recommend applying a 1/4" layer of underlayment over the OSB for installation of resilient and wood flooring. The main thing to remember about traditional OSB is that it is very absorptive and swells when exposed to moisture (such as rain). This swelling is not good for floor installation. Having said that, there are new OSB products out there that are “engineered” materials, making them different from traditional chip/strand OSB. Some of these new engineered OSB boards have much better moisture resistance and can handle water contact without a change in dimensional properties.