|Aluminum coated roofs are very difficult to scan,and I've been told not to bother.
If there is a layer of perlite or fiberboard insulation beneath the surface you may get good enough readings on the wet areas but beware of false readings. Any low spots, dirt or debris will show up as hot. Also, how well the coating was applied is a factor as thiner layers of coating will show up as warmer than the thicker layers. I suggest that if you do the scan, confirm,confirm, confirm.
Here is a recent photo that shows a suspected area that in fact was not.