Tom McNutt (Boccemon.com) says..."I have referred several people to a product made by Awn-Tex." http://www.fabricsandvinyls.com/products/awntex/index.htm {Click the photo above to view Awn-Tex web site.}"What I like best about this product is that it is permeable, durable, and comes in many colors. The down side of any cover is that it produces shade and this in turn is a perfect breeding ground for moss communities. If this is an acceptable side effect have the tent or awning company place grommets every 2' around the perimeter for easy tie downs. We like to refer folks to Rainier Tent at http://www.rainier.com/ ."