1. What is the Rafter Length Formula?

The rafter length formula is based on the Pythagorean theorem and calculates the diagonal length of a single slope roof rafter using the horizontal run and vertical rise measurements.

2. How Does the Calculator Work?

The calculator uses the Pythagorean theorem:

Where:

• \( \text{run} \) — Horizontal distance (in feet)
• \( \text{rise} \) — Vertical distance (in feet)
• \( \text{Length} \) — Diagonal rafter length (in feet)

Explanation: This formula calculates the hypotenuse of a right triangle formed by the run and rise measurements, giving you the exact rafter length needed.

3. Importance of Accurate Rafter Calculation

Details: Accurate rafter length calculation is crucial for proper roof construction, ensuring structural integrity, proper water drainage, and efficient material usage.

4. Using the Calculator

Tips: Enter the horizontal run and vertical rise measurements in feet. Both values must be positive numbers. The calculator will provide the diagonal rafter length.

5. Frequently Asked Questions (FAQ)

Q1: What units should I use for measurements?
A: This calculator uses feet for both input and output. Convert other units to feet before calculation.

Q2: Does this work for any roof pitch?
A: Yes, this formula works for any single slope roof regardless of pitch, as long as you have accurate run and rise measurements.

Q3: Should I add extra length for overhangs?
A: Yes, this calculation gives the basic rafter length. Add additional length for any desired overhangs beyond the building footprint.

Q4: How precise should my measurements be?
A: For construction purposes, measure to the nearest 1/8 inch (0.01 feet) for best results.

Q5: Can I use this for compound roof designs?
A: This calculator is designed for simple single slope roofs. Compound roofs with multiple slopes require more complex calculations.