I have a flat, metal roof with slight 'ponding' (gone in ~48hrs). I want to re-coat the roof. It currently has an aluminum coating on it. I was to cover it with an elastomeric silicone coat. I've read that the silicone stands up best to water. QUESTION: 1) Are there any issues with putting elastomeric on top of an aluminum coat? 2) Does anyone have an alternate suggestion to using elastomeric silicone in this situation? Sta-Kool 780 is what I plan to use. Thanks so much,

Here is the whole story. It is an enclosed porch about 7x12 used as a laundry room. It has always been leaky. It has some slope--not sure how much. It is not nearly a flat roof. I replaced the sheathing, laid down roofing paper horizontally, then roll roofing the same way, followed by shingles to cover the roll roofing. All layers go under the adjacent roof of the house. At the edges there is also an additional strip of asphalt. It successfully sealed the room in the worst storms so far ( the drought has hampered my troubleshooting efforts), but it leaks at the outer wall in one spot. Part of my frustration is it is not apparent whether it is leaking through the roof or the wall. It only leaks in an extreme storm when the rain is coming at it horizontally. There were some cracks where the rafter comes through the wall, so I sealed that up. It did not stop the leak. I also opened up a small section of the drywall to expose the roof and wall in that area. But there is no darkening of the wood. The leak is not enough to drip. The evidence of it is bubbling of the paint and the drywall feels moist underneath the bubbles. The bubbling does not go all the way to the roof but stops about 3 " below. This suggested a wall leak but I have sealed the cracks as I already stated. The wall is 2x4 frame with vertical plywood siding. I have considered stuffing tar under the area but I am afraid of just making a mess or damaging the roofing. What are some good ideas to deal with an evasive leak like this one, either to troubleshoot it or to cure it?