Moderate

ZIP Code 21791

Frederick County, Maryland — Unionville

30PSF (Ground Snow Load)
ModerateClassification

What This Means

Frederick County, Maryland has a moderate ground snow load of 30 PSF per ASCE 7-22. This load requires proper structural consideration during design. Roof framing, trusses, and connections should be engineered for this snow load. Ensure adequate drainage to prevent ponding.

Snow Load Details

ZIP Code21791
CountyFrederick
CityUnionville
StateMaryland (MD)
Ground Snow Load30 PSF — Moderate
Classification Range21 - 40 PSF
Data QualityMeasured

Source: ASCE 7-22 ground snow load polygons via ArcGIS

Roof Snow Load Calculator

ASCE 7-22 flat roof formula:  pf = 0.7 × Ce × Ct × Is × pg

Your ground snow load (pg): 30 PSF

Roof Snow Load: 21 PSF

ⓘ Simplified estimate for flat roofs. Sloped roofs, drift zones, and unbalanced loads need additional calculations. Consult a structural engineer for final design.

Frederick County Snow Load Map

Counties colored by snow load classification. Gray = No Load, Blue = Light, Amber = Moderate, Orange = Heavy, Red = Extreme, Purple = Case Study.

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Nearby ZIP Codes

21788 CS Case Study 21790 30 PSF Moderate 21792 25 PSF Moderate 21793 30 PSF Moderate 21794 25 PSF Moderate

Frequently Asked Questions

What is the ground snow load for ZIP code 21791?

ZIP code 21791 is in Frederick County, Maryland, with a ground snow load of 30 PSF, classified as moderate per ASCE 7-22.

Is my roof strong enough for snow in 21791?

With a moderate ground snow load of 30 PSF, standard residential construction typically handles this load, but verify with your local building code.

What county is ZIP code 21791 in?

ZIP code 21791 is in Frederick County, Maryland (MD).