1. What is a Snow Load Calculator in PSF?

Definition: This calculator determines the design snow load in pounds per square foot (PSF) based on ground snow load and various adjustment factors.

Purpose: It helps architects, engineers, and builders calculate roof snow loads for structural design according to building codes.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( PSF \) — Design snow load (lb/ft²)
• \( P_g \) — Ground snow load (lb/ft²)
• \( C_e \) — Exposure factor (unitless)
• \( C_t \) — Thermal factor (unitless)
• \( I_s \) — Importance factor (unitless)

Explanation: The ground snow load is multiplied by various factors that account for exposure, thermal conditions, and building importance.

3. Importance of Snow Load Calculation

Details: Proper snow load calculation ensures roof structures can safely support expected snow accumulation, preventing collapse and ensuring safety.

4. Using the Calculator

Tips: Enter the ground snow load for your location (available from local building codes), and appropriate factors (defaults provided). All values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: Where do I find ground snow load data?
A: Check local building codes or ASCE 7 maps. Many municipalities provide this information.

Q2: What are typical values for exposure factor (C_e)?
A: Typically 0.7-1.2 (0.7 for fully exposed, 1.0 for normal, 1.2 for sheltered areas).

Q3: When would thermal factor (C_t) be less than 1.0?
A: For unheated structures or those maintained below freezing (typically 1.0 for heated, 1.1-1.2 for others).

Q4: How is importance factor (I_s) determined?
A: Based on building occupancy category (1.0 for normal, 1.1-1.2 for essential facilities).

Q5: Does this include rain-on-snow surcharge?
A: No, additional calculations may be needed for this condition in some regions.