Valley Rafter Calculator Pro USA
Precise Framing Calculations for American Construction
Project Dimensions
/
Inches
Feet
Inches
Valley Rafter Length
—
Line Length (Long Point to Long Point)
Valley Pitch
–°
Adjusted Run
—
Schematic View
How to Calculate Valley Rafter Length (USA Method)
Using this Valley Rafter Calculator Pro (USA) is the fastest way to get accurate cuts. In the United States, roof framing is typically done using the “Pitch” method (Rise over Run). A valley rafter is different from a common rafter because it runs diagonally from the ridge to the corner of the building.
The Formula
To calculate manually, you need the Common Rafter Length and multiply it by 1.4142 (the diagonal of a square).
- Step 1: Find your run: (Building Span / 2) minus half the ridge thickness.
- Step 2: Calculate the Common Rafter Length for that run.
- Step 3: Multiply that length by 1.4142 to get the Valley Rafter length.
Frequently Asked Questions
Q: Does this include the overhang?
A: No, this calculates the length from the ridge to the wall plate. You must add your tail (overhang) length separately.
A: No, this calculates the length from the ridge to the wall plate. You must add your tail (overhang) length separately.
Q: Why is the result in fractions?
A: This tool is optimized for USA tape measures, which use inches and fractions (e.g., 1/2, 3/4) rather than decimals.
A: This tool is optimized for USA tape measures, which use inches and fractions (e.g., 1/2, 3/4) rather than decimals.
© 2023 Valley Rafter Calculator Pro
