1. What is Slope Ratio?

Slope ratio represents the relationship between vertical rise and horizontal run in pergola roof construction. It's expressed as a ratio (e.g., 1:20) that indicates how much 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 millimeters (mm)
• Run — Horizontal change in meters (m)

Explanation: The formula calculates the ratio between vertical rise and horizontal run, which is essential for proper water drainage in pergola roofs.

3. Importance of Proper Roof Slope

Details: Correct slope ratio is crucial for effective water drainage, preventing water pooling, maintaining structural integrity, and complying with Australian building standards for outdoor structures.

4. Using the Calculator

Tips: Enter rise in millimeters and run in meters. Both values must be positive numbers. Typical Australian pergola slopes range from 1:20 to 1:40 ratios.

5. Frequently Asked Questions (FAQ)

Q1: What is the minimum slope ratio for pergolas in Australia?
A: Most Australian standards recommend a minimum slope of 1:40 (approximately 2.5° pitch) for adequate water drainage.

Q2: How does slope ratio relate to pitch angle?
A: Slope ratio can be converted to degrees using the arctangent function: angle = arctan(rise/run).

Q3: Why use mm for rise and meters for run?
A: This mixed-unit approach is common in Australian construction for precision in rise measurements while maintaining practicality for run measurements.

Q4: Are there different slope requirements for different roofing materials?
A: Yes, some materials like polycarbonate sheeting may require steeper slopes than Colorbond steel for optimal performance.

Q5: Does slope ratio affect pergola height regulations?
A: Yes, steeper slopes may affect overall structure height, which is regulated by local council planning schemes in Australia.