1. What is Slope Ratio?

Slope ratio represents the relationship between vertical rise and horizontal run in roofing and construction. It's expressed as a ratio (e.g., 1:4) indicating how many units the roof rises for each unit of horizontal distance.

2. How Does the Calculator Work?

The calculator uses the slope ratio formula:

Where:

• \( rise \) — Vertical change (in feet or other units)
• \( run \) — Horizontal change (in feet or other units)

Explanation: The ratio is typically expressed with the rise value normalized to 1 (e.g., 1:4 means 1 unit up for every 4 units across).

3. Importance of Roof Slope Calculation

Details: Proper roof slope is crucial for water drainage, structural integrity, and material selection. Different roofing materials require specific minimum slopes to function properly.

4. Using the Calculator

Tips: Enter both rise and run values in the same units (typically feet). Both values must be positive numbers greater than zero for accurate calculation.

5. Frequently Asked Questions (FAQ)

Q1: What's the difference between slope ratio and slope percentage?
A: Slope ratio (e.g., 1:4) shows the relationship between rise and run, while slope percentage expresses rise as a percentage of run (e.g., 25% for 1:4 ratio).

Q2: What is the minimum slope for different roofing materials?
A: Asphalt shingles typically need at least 4:12 slope, metal roofing can go as low as 1:12, while built-up roofs require at least 1:48 slope.

Q3: How do I convert slope ratio to degrees?
A: Use the formula: angle = arctan(rise/run). Many online calculators can perform this conversion automatically.

Q4: Can I use different units for rise and run?
A: No, both measurements must be in the same units for the ratio to be meaningful and accurate.

Q5: What's a typical residential roof slope?
A: Most residential roofs have slopes between 4:12 and 9:12, though this varies based on architectural style and climate.