SnowLoadCheck

Putnam County, MO Roof Snow Load - 20 psf

Putnam County, MO roof snow load, translated

Moderate
20 psf

A typical heated home in Putnam County is designed to carry 20 pounds per square foot of snow on its roof, per ASCE 7-22. The physics-based figure alone would be 14 psf, but ASCE 7's own low-slope minimum (§7.3.4) sets a floor of 20 psf for flat and low-pitch roofs here, which is the number that actually governs.

On a roof that means 44 in. of fresh snow, 16 in. once it packs down, or 4 in. of solid ice - three very different piles for the same load. A meaningful design load. Most homes built to modern code handle it, but additions, carports, and flat-roofed sections are worth a second look.

Got real snow on a Putnam County roof right now?

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Putnam County in numbers

Where Putnam County ranks

#79 of 115 Missouri counties by design load, top 45% of 2,758 nationally - that's Putnam County's spot. That's 1.4 psf above Missouri's own county-average design load of 18.6 psf.

FIPS 29171, population 4,539, centered near 40.4786°N 93.0145°W. ASCE 7's underlying ground snow load here is 20 psf before the code's exposure and importance factors bring it to the 20 psf design figure above.

Putnam County: average annual snowfall

Putnam County sees about 28.7 in. of snow most winters, per the UNIONVILLE, MO US station's 1991-2020 NOAA normal. See the density guide.

Read this before you use Putnam County's figure

The figure above assumes the case ASCE 7-22 treats as typical: a heated, ordinary-occupancy home on a partially exposed site. Change any of those - exposure, heating, roof pitch, occupancy category - and the real design number moves.

A building permit needs the number at your exact address, not the county average - the free ASCE 7 Hazard Tool returns that from your coordinates in about a minute and produces a PDF a plan reviewer will accept. See the methodology guide.