1. What is the Rafter Length Formula?

The rafter length formula calculates the length of a single slope roof rafter using the Pythagorean theorem. It determines the diagonal distance from the top of the wall plate to the ridge board based on the horizontal run and vertical rise measurements.

2. How Does the Calculator Work?

The calculator uses the Pythagorean theorem:

Where:

• \( \text{run} \) — Horizontal distance (feet)
• \( \text{rise} \) — Vertical distance (feet)

Explanation: The formula calculates the hypotenuse of a right triangle where the run and rise form the two perpendicular sides.

3. Importance of Rafter Length Calculation

Details: Accurate rafter length calculation is essential for proper roof construction, ensuring structural integrity, proper material estimation, and avoiding construction errors.

4. Using the Calculator

Tips: Enter the horizontal run and vertical rise measurements in feet. Both values must be positive numbers greater than zero for accurate calculation.

5. Frequently Asked Questions (FAQ)

Q1: What units should I use for measurements?
A: The calculator uses feet for both run and rise measurements. Convert other units to feet before calculation.

Q2: Does this work for all roof types?
A: This formula is specifically for single slope (shed) roofs. Other roof types may require different calculations.

Q3: Should I add extra length for overhangs?
A: Yes, this calculation gives the basic rafter length. Additional length should be added for any desired overhangs beyond the wall plates.

Q4: How precise should my measurements be?
A: For construction purposes, measurements should be precise to at least 1/8 inch (0.01 feet) for accurate results.

Q5: Can I use this for roof pitch calculations?
A: While related, roof pitch is typically expressed as a ratio (rise:run). This calculator focuses specifically on rafter length.