ASCE 7-22 Snow Load Calculator
This professional-grade calculator computes balanced roof snow loads per ASCE 7-22. It is designed for structural and civil engineers, plan reviewers, and advanced practitioners who need fast, defensible calculations aligned with the standard. Enter your mapped ground snow load and project factors to obtain flat-roof and sloped-roof design values.
Calculator
All required fields are marked with an asterisk.
Results
Note: This tool reports balanced snow loads. Evaluate drift, unbalanced, sliding, rain-on-snow, and other conditions per ASCE 7-22 as applicable.
Data Source and Methodology
Authoritative data source: ASCE/SEI 7-22, Minimum Design Loads and Associated Criteria for Buildings and Other Structures (2022). Official page — ASCE Library (DOI: 10.1061/9780784416136).
All calculations in this tool strictly follow the ASCE 7-22 balanced snow load provisions: flat-roof snow load pf and sloped-roof snow load ps with user-provided Cs from ASCE 7-22 Figure 7-2. Tutti i calcoli si basano rigorosamente sulle formule e sui dati forniti da questa fonte.
For mapped ground snow loads, consult the ASCE Hazard Tool. For background on ASCE 7-22 changes, see Structure Magazine’s overview: Ground Snow Loads for ASCE 7-22.
The Formula Explained
Flat-roof (balanced) snow load:
$$ p_f = 0.7 \, C_e \, C_t \, I_s \, p_g $$
Sloped-roof snow load (user supplies slope factor from ASCE 7-22 Fig. 7-2):
$$ p_s = C_s \, p_f $$
Optional rain-on-snow surcharge:
$$ p_{\text{total}} = p_s + R $$
Glossary of Variables
- pg: Ground snow load from ASCE maps or hazard tool (psf or kPa).
- Ce: Exposure factor per ASCE 7-22 (unitless).
- Ct: Thermal factor per ASCE 7-22 (unitless).
- Is: Importance factor per Risk Category (unitless).
- pf: Balanced flat-roof snow load (psf or kPa).
- Cs: Slope factor from ASCE 7-22 Figure 7-2 (unitless).
- ps: Sloped-roof snow load (psf or kPa).
- R: Rain-on-snow surcharge (psf or kPa), if applicable.
How It Works: A Step-by-Step Example
- Set unit system to US (psf). Enter pg = 40 psf, Ce = 1.0, Ct = 1.0, Importance Category II (Is = 1.0).
- Compute flat-roof load: using pf = 0.7 × Ce × Ct × Is × pg = 0.7 × 1.0 × 1.0 × 1.0 × 40 = 28 psf.
- For a sloped roof, obtain Cs from ASCE 7-22 Fig. 7-2. If Cs = 0.90, then ps = Cs × pf = 0.90 × 28 = 25.2 psf.
- If rain-on-snow surcharge applies (e.g., R = 5 psf), total = ps + R = 30.2 psf.
Frequently Asked Questions (FAQ)
Which version of the standard does this use?
ASCE/SEI 7-22 (2022). The formulas implemented are from Chapter 7, Snow Loads.
How do I find pg (ground snow load)?
Use the ASCE Hazard Tool to get mapped values for your site. Local amendments may apply.
Can the tool calculate Cs for me?
No. ASCE 7-22 provides Cs via Figure 7-2, which depends on roof slope and surface properties. Enter the value from the standard to ensure compliance.
Does this include drift, unbalanced, sliding, or ponding checks?
This tool focuses on balanced snow loads. You must evaluate additional load cases and serviceability conditions separately per ASCE 7-22.
What if my project uses SI units?
Toggle to SI (kPa). The tool converts inputs and outputs between psf and kPa consistently.
Are there minimum loads I must apply?
ASCE 7-22 includes minimum roof snow load criteria in certain cases. Verify all applicable minimums and governing load combinations for your project.