Roof Snow Load Calculator
Flat-roof sketch pf equals 0.7 times Ce times Ct times I times ground snow pg. Optional roof area multiplies pf into total pounds. Estimate only, not a permit, code check, or engineered design.
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How to sketch flat-roof snow load
- Enter ground snow load pg in psf from your map or local note.
- Enter exposure Ce, thermal Ct, and importance I. Each factor stays above 0 and at most 1.5.
- Optionally enter roof area so the page can show total load in pounds.
- Read pf, the factor product, and total pounds when area is greater than 0. Estimate only.
Flat roof snow load pf
ASCE-style sketch with typed factors
| Formula | pf = 0.7 × Ce × Ct × I × pg |
|---|---|
| Ground snow | pg in psf |
| Factor bounds | Ce, Ct, and I from greater than 0 to 1.5 |
| Optional area | Total load = pf × area when area > 0 |
| Omitted | Slope Cs, drifting, unbalanced snow, and local amendments |
| Compliance | Estimate only. Not a permit, code check, or engineered design. |
What this snow load page covers
You type ground snow pg and three factors. The page returns a simplified flat-roof pf. Slope factor Cs, drifting, and unbalanced loads stay out. Pitch helpers sit on roof pitch. Area takeoff sits on roof area.
How pf is computed
pf = 0.7 × Ce × Ct × I × pg. Each of Ce, Ct, and I must be greater than 0 and at most 1.5. If area is greater than 0, total load is pf times area. Units stay as you typed them. The engine does not look up a jurisdiction map.
Factors, maps, and nearby roof tools
Exposure, thermal, and importance values come from the code path your engineer or AHJ uses. This page only multiplies what you enter. Material counts for panels or bundles are on metal roofing and shingles.
Use cases
Compare how Ce or I changes pf on the same pg. Rough total pounds on a typed roof area before you talk to a designer. Not a sealed calculation.
Limits
No Cs slope reduction, no drift surcharge, and no automatic map lookup. Estimate only, not a permit, code check, or engineered design. See the disclaimer. Nothing is uploaded.