Slope (or pitch) measures the amount of rise your roof has compared to the length. In other words, for every twelve inches of length your roof will rise a set number of inches. The diagram below illustrates a roof that has a seven inch rise for every 12 inches of length thus it has a 7 inch slope or pitch. (also expressed 7 in 12)
Measuring Slope
An easy way to measure slope is to take level and mark where 12 inches is. (assuming it is longer than one foot) Place the level with one end on the roof and raise the other end until it is level. Next take a tape measure and determine the number of inches between the roof and the spot you have marked on your level. You now have the amount of slope for your roof.
Simplified Slope
Flat Roof - Flat or with just the slightest amount of a pitch to them.
Low Slope Roof - Usually around a 2-3 in pitch roof that is easily walkable with normal footing.
Medium Slope Roof - Considered 4-6 in pitch roof, it is walkable with normal footing.
Steep Slope Roof - Any pitch above 6 in, this is a roof that is not walkable without assistance.
