Be sure to have at the very least 6 inches from each mounting corner to properly tighten the sail. having 12 inch is probably better! Also, please be aware that this sail does not come with mounting hardware so you must purchase that separately. Colourtree does provide kits that I found work quite well and are good value. Also, you should mount the sail at an angle. This thing is really waterproof so you will want the water to go somewhere off the edge. hanging it level might result in a puddle and premature wear. I have had this sail up permanently for about three weeks now. Desite what the colour might indicate it is rather dark underneath so take that into account. The sail has weathered sun, rain, hail, thunderstorms and heavy gusts without any sign of wear. I am happy to see how well it performs and anticipate it will hold for quite some time.