Enter the roof slope, length of the roof, width of the building, and the allowable stress of the beam material into the calculator to determine the required size of the ridge beam.

Ridge Beam Formula

The following formula is used to calculate the size of a ridge beam in a roof structure.

RB = (S * L * W) / (8 * F)

Variables:

  • RB is the required size of the ridge beam
  • S is the roof slope
  • L is the length of the roof
  • W is the width of the building
  • F is the allowable stress of the beam material

To calculate the size of the ridge beam, multiply the roof slope by the length of the roof, then multiply the result by the width of the building. Divide this result by the product of 8 times the allowable stress of the beam material.

What is a Ridge Beam?

A ridge beam is a structural element used in construction, specifically in roof framing. It runs along the apex of a sloping roof, essentially the highest horizontal line of the roof, and is designed to support the roof’s load, distributing the weight of the roof onto the walls of the structure. The rafters or trusses of the roof are attached to the ridge beam, providing stability and preventing the roof from sagging or collapsing.

How to Calculate Ridge Beam?

The following steps outline how to calculate the required size of a Ridge Beam.


  1. First, determine the roof slope (S).
  2. Next, determine the length of the roof (L).
  3. Next, determine the width of the building (W).
  4. Next, determine the allowable stress of the beam material (F).
  5. Finally, use the formula RB = (S * L * W) / (8 * F) to calculate the required size of the ridge beam (RB).

Example Problem:

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

Roof slope (S) = 5

Length of the roof (L) = 10

Width of the building (W) = 8

Allowable stress of the beam material (F) = 5000