Deck builder in Johnstown CO
Johnstown was platted in 1902 by Harvey J. Parish and named for his young son John, who was in the hospital at the time; John later served as mayor. It sits just west of where the Big Thompson and Little Thompson rivers meet, about ten miles west-southwest of Greeley and nine southeast of Loveland, and it reached 17,303 residents in 2020 on land in both Weld and Larimer counties.
The open ground around Johnstown means wind and sun from every side, which makes shade and solid framing matter: a covered deck, a screened porch, or a composite deckthat won't need sealing in the sun.
Johnstown design criteria for a deck
| Criterion | Johnstown |
|---|---|
| Ground snow load | 30 psf |
| Wind design speed | 115 mph |
| Frost line depth | 30 in |
| Seismic design category | B |
| Weathering | Severe |
| Air freezing index | 1000 |
| Mean annual temperature | 43 F |
| Ice barrier underlayment | Required |
Source: Town of Johnstown Building Codes page, read November 2026.
For a deck, the frost line sets pier depth, 30 inches for an attached deck, and the snow load sets the framing for any roof or cover over it. The "severe" weathering rating is the code's way of saying freeze-thaw is hard on exposed concrete and materials here. Compare the numbers with Fort Collins and the other towns in the footing depth and snow load guide. Source: Johnstown Building Codes.
Codes in force
Johnstown lists the 2024 International Residential Code with the rest of the 2024 I-codes, the 2023 National Electrical Code, the Colorado Wildfire Resiliency Code and Colorado's electric- and solar-ready code. How the wildfire code applies to a given lot is a question for the Town; Larimer County's version is explained in the wildfire code guide.
