Johnson County, IN Roof Snow Load - 20 psf
How much snow is too much for a roof in Johnson County, IN?
20 psf: that's what ASCE 7-22 requires a typical heated home's roof in Johnson County to carry. ASCE 7's low-slope-roof minimum (§7.3.4) raises the governing figure to 20 psf - higher than the 14 psf the ground-load formula alone would give, and the code says use the larger one.
Picture it, not just weigh it: 44 in. if it's fresh powder, 16 in. once it settles, or a mere 4 in. if it's ice. A meaningful design load. Most homes built to modern code handle it, but additions, carports, and flat-roofed sections are worth a second look.
Johnson County at a glance
- Design roof snow load20 psf
- Ground snow load, ASCE 7 map20 psf
- National rank#604 of 2,758
- Indiana rank#8 of 89
- Population170,614
- Annual snowfall, NOAA normal16.9 in.
- FIPS18081
How Johnson County compares
20 psf ranks #604 of 2,758 US counties with a mapped snow load (top 22%) - and #8 of 89 in Indiana. Indiana counties average 19.3 psf; Johnson County runs 0.7 psf higher than that.
Population 170,614 (FIPS 18081), roughly 39.4961°N 86.0943°W. The 20 psf ground snow load ASCE 7-22 maps here becomes 20 psf once the code's own design factors are applied.
Typical snowfall in Johnson County, IN
NOAA's 30-year normal for Johnson County: 16.9 in. of snow a year, from the FRANKLIN WWTP, IN US station. (fresh vs. packed vs. ice explains why.)
What this Johnson County figure assumes
This is a county-level reference figure for a typical heated home built to Risk Category II (ordinary residential), on a partially exposed lot - the assumptions ASCE 7-22 itself treats as the default case. A steeper roof, a fully exposed hilltop lot, an unheated structure, or a higher risk category all change the actual number.
Johnson County's permit office wants an address-specific figure, not this county average - the ASCE 7 Hazard Tool is free, takes under a minute, and outputs a PDF most reviewers accept. (How this figure is calculated.)