I notice that water pools up over a mostly filled in downspout fairly often on my built up roof. The downspout goes maybe 3-4 inches deep before I hit a rough and very hard rubbery surface (I can't tell exactly what material it is).
I'm worried this semi-constant pool of water will reduce the lifespan of the roof.
My neighbor suggested filling it in with gravel. Will that work? Or should I fill it in with something else?