Enter the rise and span of the roof into the calculator to determine the length of the collar tie.

## Collar Tie Formula

The following formula is used to calculate the length of a collar tie.

CT = sqrt((R^2) + (S^2))

Variables:

- CT is the length of the collar tie (ft or m) R is the rise of the roof (ft or m) S is the span of the roof (ft or m)

To calculate the length of the collar tie, square the rise of the roof and the span 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 collar tie.

## What is a Collar Tie?

A collar tie is a horizontal framing member in a roof structure, typically found in residential construction. It is installed between opposing rafters, and its primary function is to resist the outward thrust of the roof rafters under load, preventing the walls from spreading apart. Collar ties are often confused with rafter ties, but they are located higher up in the roof structure, usually in the upper third of the roof height.

## How to Calculate Collar Tie?

The following steps outline how to calculate the length of a Collar Tie using the formula: CT = sqrt((R^2) + (S^2)).

- First, determine the rise of the roof (R) in feet or meters.
- Next, determine the span of the roof (S) in feet or meters.
- Next, substitute the values of R and S into the formula CT = sqrt((R^2) + (S^2)).
- Finally, calculate the length of the collar tie (CT).
- After inserting the values and calculating the result, check your answer with a calculator.

**Example Problem:**

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

Rise of the roof (R) = 8 feet

Span of the roof (S) = 10 feet