When I called the Liquid Roof people they told me to spray the Eterna-Bond with a contact glue and let the glue dry. When dry just apply the Liquid Roof over the old roof and tape. I will be doing my roof one gallon at a time over several months. I have Limb Girdle Muscular Dystrophy and cannot work that long a period of time with out damaging my body so I do a little bit at a time. The Liquid Roof staff said this was OK to do it this way. I just have to buy the product in small containers instead of the large 5 gallon pail.