[Daniel Holzman]

Typically deck slope of 1 to 2 percent is adequate to shed water, without becoming a visual problem. The definition of a 1% slope is that the deck falls 1 inch for every 100 inches of deck. You can convert percent slope to degrees by knowing that the tangent of an angle is the slope, so if the slope is say 1 percent (which you need to convert to decimal or .01), the angle corresponding to the 1 percent slope is the arc tangent of .01, which you can get off any scientific calculator. Arc Tan .01 = 0.57 degrees. On some calculators, Arc Tan is shown as Tan-1 (inverse tangent). If you do not have access to a scientific calculator, you can use this website to convert slope in percent to degrees http://www.calcunation.com/calculator/slope-percent-conversion.php.

By the way, many people do not put any slope on their deck, myself included. If there is adequate space between the boards, typically at least 1/8 inch, the water will drain, and snow never drains anyway. Your call.