30 psf ground, Ce 0.9, Ct 1.0, Is 1.0, Cs 0.85
- Roof load ≈ 30 × 0.9 × 1 × 1 × 0.85 ≈ 22.95 psf
construction calculator
Snow Load Calculator
Estimate roof snow load using ground snow load and adjustment factors (simplified).
Results
- Estimated roof snow load (psf)
- 22.95
How to use this calculator
- Enter ground snow load (psf).
- Adjust exposure, thermal, importance, and slope factors as needed.
- Review estimated roof snow load (psf).
Inputs explained
- Ground snow load
- From local building code/ASCE data for your location.
- Exposure factor
- Adjusts for wind exposure; often <1 for exposed roofs.
- Thermal factor
- Adjusts for heat loss; warm roofs may have lower values.
- Importance factor
- Higher for critical structures; default 1 for typical buildings.
- Slope factor
- Reduces load on sloped roofs; adjust based on roof slope.
How it works
Roof snow load = Ground snow load × Ce × Ct × Is × Cs (simplified). Adjust factors to match your conditions.
Formula
Roof snow load = Pg × Ce × Ct × Is × Cs
When to use it
- Rough roof snow load estimation for early design checks.
- Comparing loads for different roof slopes/exposure assumptions.
- Quick sanity checks before consulting structural tables or engineers.
Tips & cautions
- Use local code values for ground snow load and factors.
- For flat roofs or low slope, slope factor approaches 1; steep roofs reduce Cs.
- Consult ASCE/engineering guidance for precise calculations.
- Simplified; not a substitute for code-compliant structural design.
- Does not include drifting, unbalanced loads, or detailed ASCE procedures.
- Consult a structural engineer for actual design loads.
Worked examples
50 psf ground, Ce 0.8, Ct 1.0, Is 1.0, Cs 1.0
- Roof load ≈ 50 × 0.8 × 1 × 1 × 1 = 40 psf
Deep dive
Estimate roof snow load by entering ground snow load and adjustment factors (exposure, thermal, importance, slope).
Use this as a quick, simplified check; verify with local codes and engineers for design.
FAQs
- Is this code compliant?
- No. It’s a simplified estimate. Use ASCE/local code and a structural engineer for design loads.
- Does this include drifting/unbalanced snow?
- No. It’s a uniform load estimate only.
- Where do I get ground snow load?
- From local building code or ASCE maps/tables for your location.
- Does roof slope reduce load?
- Yes. Cs < 1 for sloped roofs; steep roofs shed more snow.
- Is this structural engineering advice?
- No. Consult a licensed engineer for design-critical calculations.
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Simplified snow load estimate. Not for structural design. Consult local codes and a structural engineer for accurate design loads.