How To Measure Roof Pitch

When installing a chimney you will usually need to know your roof's pitch to properly size the roof flashing.  This guide will explain how to measure your roof's pitch.

For this task you are going to need a level that is at least 12" long and a tape measure.  Measure and mark 12" on your level.  This is known as the "run" and roof's are measured in 12" run increments.

Now, hold the level so the 12" mark is on the bottom of the level closest to the roof.  While holding it level measure the space from the bottom of the level to the roof at your 12" mark.  This measurement is the "rise".

If, for example, the measurement is 6" then you have a 6/12 roof pitch.  That equates to 6" of rise for every 12" of run.  A roof's pitch is always displayed as Rise/Run.

This process can also be done in reverse and used to measure from inside the home in the attic or in the home for cathedral ceilings.

That's all there is to it. Now you know your roof's pitch and can choose the proper Roof Flashing for your installation.