What is an underlayment? Unfortunately, right now there isn't one specific definition or ANSI Standard so everyone has a different definition. In this module, we will take a look at how underlayments are used and the products on the market that can be used in an underlayment application. To complete this course and receive a certificate of completion, you will need to complete the on-line course which will take a minimum of 7 minutes to complete and then you will be required to take a 10 question quiz to test what you have learned.