1. What is Snow Drift Load?

Snow drift load refers to the additional snow accumulation that occurs when wind causes snow to deposit in certain areas, creating uneven loads on roofs and structures. This localized accumulation can significantly exceed the uniform snow load.

2. How Does the Calculator Work?

The calculator uses the snow drift load equation:

Where:

• \( \rho \) — Snow density (pounds per cubic foot, pcf)
• \( h \) — Height of snow drift (feet)
• \( \theta \) — Angle of roof slope (degrees)

Explanation: The equation accounts for the triangular distribution of snow in drifts, with denser snow accumulating on sloped surfaces.

3. Importance of Drift Load Calculation

Details: Accurate drift load estimation is crucial for structural design in snowy regions, preventing roof collapses and ensuring building safety during winter months.

4. Using the Calculator

Tips: Enter snow density in pcf (typically 10-30 pcf for fresh snow, up to 50 pcf for settled snow), drift height in feet, and roof angle in degrees. All values must be positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: What's a typical snow density value?
A: Fresh snow is about 10 pcf, settled snow 20-30 pcf, and wind-packed snow can reach 40-50 pcf. Ice is about 57 pcf.

Q2: How does roof angle affect drift load?
A: Steeper roofs (higher angles) generally accumulate less snow as it slides off, while low-slope roofs collect more drifting snow.

Q3: Where do snow drifts typically form?
A: Drifts form on leeward sides of roof steps, parapets, and other obstructions that disrupt wind flow.

Q4: Are there code requirements for drift loads?
A: Yes, ASCE 7 and IBC provide detailed requirements for calculating and applying drift loads in structural design.

Q5: Should this be used for final structural design?
A: This provides an estimate. For actual design, consult local building codes and a structural engineer.