Wood must Constructed of lumber that is heat-treated using a conventional steam or dry kiln heat chamber to 56 degrees Celsius core temperature for 30 continuous minutes throughout the entire profile of the wood; or, constructed of untreated lumber and then heat-treated using a conventional steam or dry kiln heat chamber to 56 degrees Celsius core temperature for 30 continuous minutes throughout the entire profile of the wood. And contain ISPM 15 Certification Mark HT for heat treatment (HT)