Flat-Roof Snow Load

The design snow load on a flat roof, from the ground snow load for the site.

Run the calculator

Example

You enter

Ground snow load Pg (psf) 30
Exposure factor Ce 1
Thermal factor Ct 1
Importance factor Is 1

You get

Flat-roof snow load Pf 21 psf
Pg (psf) 30

Details, formula, and sources

Pf = 0.7 * Ce * Ct * Is * Pg per public ASCE 7.

Flat-roof snow load Pf = 0.7 × Ce × Ct × Is × Pg (psf). Public ASCE 7-22 formula. Pg from NOAA ground-snow maps.

ASCE 7-22 (Minimum Design Loads for Buildings and Other Structures). Section 7.3.

ASCE 7 licensed; principles free in published structural texts. NOAA ground-snow data free at hazards.atcouncil.org.

Estimate. AHJ and licensed structural engineer govern.

Field names used by the API: Pg_psf, Ce, Ct, Is, Pf_psf

Default Ce / Ct / Is 1.0 / 1.0 / 1.0 (Cat II, partially exposed, heated) unless user suppliesASCE 7-22 §7.3
Pg map data/construction/wind-snow-zones.jsonNOAA / ASCE 7-22

Details, formula, and sources

Pf = 0.7 * Ce * Ct * Is * Pg per public ASCE 7.

Flat-roof snow load Pf = 0.7 × Ce × Ct × Is × Pg (psf). Public ASCE 7-22 formula. Pg from NOAA ground-snow maps.

ASCE 7-22 (Minimum Design Loads for Buildings and Other Structures). Section 7.3.

ASCE 7 licensed; principles free in published structural texts. NOAA ground-snow data free at hazards.atcouncil.org.

Estimate. AHJ and licensed structural engineer govern.

Default Ce / Ct / Is 1.0 / 1.0 / 1.0 (Cat II, partially exposed, heated) unless user suppliesASCE 7-22 §7.3
Pg map data/construction/wind-snow-zones.jsonNOAA / ASCE 7-22

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