We are building a simple screened porch (24' x 18') and want to keep costs low. Original idea was to use corrugated metal sheets for roof. Framing beneath these panels would be exposed, and there would be no insulation or ceiling beneath the steel panels. The ceiling would simply be the vaulted underside of the corrugated panels, with exposed framing. I am concerned about the loud noise that would result from rainfall --the sound that we would hear during a rain storm while we are out in the screened porch. I don't think it would be pleasant. (Opinions, anyone?) Would acoustical sound-deadening paint sprayed onto the underside of the metal panels (before installation) be effective? And, if so, would it be more expensive than simply adding an underlay of ugly plywood? Possibly a plywood sheet with a tongue-and-groove appearance? Is the acoustic paint idea more cost effective? Or, is it "a wash"?