I have a friend who has an old home with a a 8ftx50ft porch. There is a bump out that is about 4ftx10ft in the dining area. The porch roof covers that section of the interior of the house. it is a low slope and it is leaking in that exact area. The homeowner wants to do a complete roof tear off in the spring. The home owner wants a temporary fix and insists on using some kind of roof coating for a a 3 or 4 month fix. There are 3 layers of shingles on there now. What can I use that will work. I already used roofing tar on the spots that looked like it might be leaking. But so far there is still a small leak.