Determining Your Roof’s Slope

How to Measure Your Roof’s Slope

If you want to determine roof slope, it isn’t as difficult as you may think. In fact, its quite simple and can be done in a very short amount of time with minimal inconvenience. The slope of a roof is measured as the length that a roof rises vertically over a 12″ horizontal distance. You can do this job yourself, ask a friend to help or call a roofing professional if you are not comfortable doing the work yourself.

Getting Into the Correct Position

To determine roof slope, place a ladder at the side of your house so that you may easily access the downslope edge of the roof. At this point, you should be in line with the roof’s peak, which means the roof should slope up from left to right or from right to left, but not away from you. Before you begin, make sure that your ladder is secured. You will need to use both hands to determine roof slope and will not want to be distracted by a shaky ladder. This can be bothersome, but also very dangerous. I can’t stress enough that when working on a ladder, make sure that it is perfectly safe. If you have trouble with heights and do not wish to climb the ladder yourself, ask a friend to help or call a roofing professional.

How To Determine Roof Slope Accurately

Now that you’re ready to get started, it’s important to know that you will not need to be on the roof to do this, which is ideal because walking directly on the roof can be dangerous. Begin by holding a framing square onto the roofline while making sure that the long end of the L is pointing toward the roof’s center and the short end is pointing down toward the ground. The long end of the framing square should meet the edge of the roof at the 12″ line. Level the square horizontally and read the measurement on the short end.

To determine roof slope, remember that rise is the measurement on the vertical leg while the run is the 12″ measurement on the horizontal line. If you are using a framing square, keep in mind that some have measurements on both edges. If that is the case with your framing square, consult the measurements on the inside edges for an accurate number. Remember that, if your roof rises 8 inches vertically for every 12 inches horizontally, then you can determine roof slope to be at 8/12.

A Few Options

If you do not have a framing square to measure roof slope, a ruler or tape measure will also work because the slope is measured based on a 12-unit horizontal distance. If you are using a tape measure, look for one that has a push lock. This will help avoid unnecessary problems with constantly having to pull the tape measure back out to double check the slope measurements.

 

 

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