1. What is Slope Ratio?

Slope ratio represents the steepness of a surface, calculated as the ratio of vertical change (rise) to horizontal change (run). For pergola roofs, this measurement helps determine proper water drainage and structural integrity.

2. How Does the Calculator Work?

The calculator uses the slope ratio formula:

Where:

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

Explanation: The ratio expresses how many units the roof rises vertically for each unit of horizontal run.

3. Importance of Slope Ratio Calculation

Details: Proper slope calculation ensures adequate water drainage, prevents water pooling, maintains structural stability, and meets building code requirements for pergola construction.

4. Using the Calculator

Tips: Enter both rise and run measurements in the same units (feet). Ensure both values are positive numbers greater than zero for accurate calculation.

5. Frequently Asked Questions (FAQ)

Q1: What is a typical slope ratio for pergola roofs?
A: Most pergola roofs use a slope ratio between 1:12 and 4:12 (1-4 inches of rise per 12 inches of run) for proper drainage.

Q2: Can I use different units for rise and run?
A: No, both measurements must use the same units. The calculator automatically uses feet, but the ratio remains the same regardless of unit type.

Q3: How does slope ratio differ from slope percentage?
A: Slope ratio is expressed as rise:run (e.g., 1:12), while slope percentage is calculated as (rise/run)×100%.

Q4: Why is proper slope important for pergolas?
A: Adequate slope prevents water accumulation, reduces structural load, prevents rot/mold, and extends the lifespan of the structure.

Q5: Can this calculator be used for other sloping surfaces?
A: Yes, the slope ratio calculation applies to any sloping surface including ramps, driveways, and other roof types.