1. What is a 4/12 Pitch Roof?

A 4/12 pitch roof means the roof rises 4 inches vertically for every 12 inches of horizontal run. This is a common roof pitch used in residential construction that provides good drainage while maintaining a relatively low profile.

2. How Does the Calculator Work?

The calculator uses these formulas:

Where:

• \( \text{Run} \) — Horizontal distance from wall to ridge (feet)
• \( \frac{4}{12} \) — Roof pitch ratio (4 inches rise per 12 inches run)
• \( \sqrt{1 + \left(\frac{4}{12}\right)^2} \) — Pythagorean theorem factor
• \( \arctan\left(\frac{4}{12}\right) \) — Inverse tangent to find angle

Explanation: The formulas calculate the actual rafter length (hypotenuse) and roof angle based on the horizontal run and fixed 4/12 pitch ratio.

3. Importance of Roof Pitch Calculation

Details: Accurate rafter length and angle calculations are essential for proper roof framing, material estimation, structural integrity, and ensuring proper water drainage.

4. Using the Calculator

Tips: Enter the horizontal run distance in feet. The calculator will automatically compute the rafter length and roof angle based on the fixed 4/12 pitch ratio.

5. Frequently Asked Questions (FAQ)

Q1: What does 4/12 pitch mean in degrees?
A: A 4/12 pitch equals approximately 18.4 degrees, which is considered a low to moderate slope roof.

Q2: Is 4/12 pitch suitable for all climates?
A: 4/12 pitch works well in most climates but may not be ideal for areas with heavy snow loads where steeper pitches are preferred.

Q3: Can this calculator be used for other roof pitches?
A: No, this calculator is specifically designed for 4/12 pitch roofs. Other pitches require different calculations.

Q4: What materials are needed for a 4/12 pitch roof?
A: Standard asphalt shingles work well on 4/12 pitch roofs. Some roofing materials have minimum pitch requirements.

Q5: How does roof pitch affect attic space?
A: A 4/12 pitch provides limited attic space compared to steeper pitches, but more headroom than flatter roofs.