Knowing the pitch of your home's roof is useful for room additions and new skylights. The angle, or pitch, is calculated by the number of inches it rises vertically for every 12 inches it extends horizontally. For example, a roof that rises 6 inches for every 12 inches of horizontal run has a ?6-in-12? pitch. Here's a safe and easy way to determine the pitch of your roof from inside the attic using only a level, a tape measure and a pencil. First measure 12 inches from one end of the level and make a mark. Then, in the attic, place that end against the bottom of a rafter. Holding it perfectly level, measure straight up from the 12-inch mark to the underside of the same rafter (making a triangle of sorts). The resulting measurement is the number of inches your roof rises in 12. Visualizing the process helps understand this ?make-sense? household labeling for roofs; level on the bottom and measure straight up 12 inches out. It's easy when you know how. And that's the On The House tip for today.