Enter the run of the structure and the rise of the roof into the calculator to determine the common rafter length. This calculator can also evaluate any of the variables given the others are known.

## Common Rafter Length Formula

The following formula is used to calculate the common rafter length.

CRL = sqrt((RS^2) + (RL^2))

Variables:

- CRL is the common rafter length (feet) RS is the run of the structure (feet) RL is the rise of the roof (feet)

To calculate the common rafter length, square the run of the structure and the rise of the roof. Add these two results together and then take the square root of the sum. This will give you the length of the common rafter.

## What is a Common Rafter Length?

A Common Rafter Length is a measurement used in roofing construction that refers to the length of the rafter, which is the beam running from the top of the roof to the bottom. This length is determined by the width of the building, the pitch (or slope) of the roof, and the thickness of the ridge. It is a crucial measurement for ensuring the structural integrity and proper construction of a roof.

## How to Calculate Common Rafter Length?

The following steps outline how to calculate the Common Rafter Length.

- First, determine the run of the structure (RS) in feet.
- Next, determine the rise of the roof (RL) in feet.
- Next, use the formula CRL = sqrt((RS^2) + (RL^2)) to calculate the Common Rafter Length.
- Finally, calculate the Common Rafter Length.
- After inserting the values of RS and RL into the formula and calculating the result, check your answer with the calculator above.

**Example Problem:**

Use the following variables as an example problem to test your knowledge.

run of the structure (RS) = 10 feet

rise of the roof (RL) = 8 feet