I've finished my cedar deck and now wish to cover it with a pergola. Trouble is, my requirements are, at first glance, mutually incompatible. I want it to be rain-proof but I don't want it to be so solid that it looks and sounds like a solid roof. I've been looking at these corrugated acrylic panels, which meet two out of three requirements, but I think that they will echo like there's a roof over your head. That's one of the things I really want to avoid. I've also thought about canvas, which would sort of be rain-proof, would sort of let light in and would definitely not reflect sound but, living in Canada, it wouldn't last very long. Besides, with the amount of trees here, it would get covered in dirt very quickly. AndI want it to be virtually zero maintenance. Do you have any ideas how I could keep the rain out while keeping the light, airy, outdoor feel?