I own a home in a tract where all the homes have entrances on the 2nd floor, over the garage. EVERY house in the tract leaks from the entry porch into the garage below. Many of the houses have rebuilt their porches several times only to have the leaks persist. The first problem is that the porches slope slightly back towards the house. The second problem is that there is no overhang above the porch. I have waited patiently watching everyone else try to fix their porch before I waste money on mine. The houses are now about 20 years old and are located in the Los Angeles area. One individual appears to have met with some success by changing the slope away from the house. Another individual tells me that he thinks he has been successful by putting down a membrane under the "Mexican Pavers" which are on the surface of all of the porches. Unfortunately, he does not know exactly what his contractor used. I think I am ready to attempt a repair and would like to incorporate both solutions. Changing the slope does not appear to be a major problem. The problem now is finding out what the proper membrane is to use under the Pavers. I once saw a Bob Vila show where they used a membrane on a roof. After they put it down they claimed you could hammer a nail through it and then pull the nail out and the membrane would not leak. This sounds like it might be on the right track. Can you please suggest what kind of membrane to use and where to get it. If you have any other suggestions I would appreciate them.