I'm getting ready to install new laminate flooring throughout my house. The existing laminate in my living room, if original to the house, is about 20 years old. (and I can't be positive that it is the original floor, but this is as old as it can be) I haven't seen the entire underlay, but what I can see appears to be in good shape. If this is the case is it okay to reuse what is there, and only add it to the new rooms (where it currently has carpet), or is this something that may encourage squeaks / issues later on. Thanks for any input.