What Snow Load Does Gunnison County Require for New Construction?

There is no single number. Gunnison County says the ground snow load "varies" by building site and comes from the 2016 Colorado Design Snow Loads report by the Structural Engineers Association of Colorado. All new construction in unincorporated Gunnison County must meet the snow load requirements at the proposed site, and the county's design criteria also list a 36-inch frost depth and 104 mph wind design.

This post covers unincorporated Gunnison County. The City of Gunnison, the Town of Crested Butte and the Town of Mt. Crested Butte have their own building departments. This is general information, not engineering or legal advice.

How does Gunnison County decide the snow load?

Per the county's Climate Design Criteria page, ground snow load is taken from the SEAoC Snow Load Committee's 2016 Colorado Design Snow Loads report and depends on the site. The roof snow load equals the report's recommended basic snow load, converted using ASCE 7 procedures. That conversion accounts for wind exposure, roof thermal properties, slope, unbalanced loads, drifting and the building's risk category. In plain language: two lots a few miles apart can have different requirements, and a roof's shape and insulation change the design too. The county's page does not list a single numeric value, so a designer or the Building Office has to confirm the number for a specific parcel.

What other design criteria does the county list?

The same page lists these for unincorporated Gunnison County:

• Frost line depth: 36 inches
• Wind design: 104 mph (3-second gust, exposure C)
• Elevation reference: 7,674 feet, based on an automated weather observing system
• Seismic design category: C, for site soil class D
• Weathering: severe, with an ice barrier underlayment required
• Winter design temperatures: outdoor winter design dry-bulb of minus 22 degrees F and indoor of 70 degrees F, used for heating calculations

A designer, builder or engineer will use these numbers, but they are not a substitute for the permit review. The county notes that all new construction must meet the snow load requirements at the proposed site.

Who do I contact about permits?

The page directs people to the Building Office at 200 E. Virginia, Gunnison, CO 81230. Call or visit before you spend money on plans so you know what the county expects for your lot.

Why does snow load matter if I am buying an existing home?

Because roofs, decks and garages in this climate carry real weight each winter. A home built decades ago may have been designed to an earlier standard, and additions or remodels may have been built differently from the original structure. Before you buy, I suggest asking:

• What permits were pulled? Ask the seller for permits for additions, roof replacements and structural work.
• How old is the roof, and what is it made of? Metal, shingle and flat roofs shed snow very differently.
• Is there a history of ice dams or leaks? These often show up as stains in ceilings and around chimneys.
• Where does the snow go? Roofs that shed over a walkway, a car or a propane tank deserve a closer look.
• Are decks, carports and outbuildings built for snow? Ask the inspector to look at them.

A general home inspection is a good start, and a structural engineer can look closer if something raises a question.

Why does frost depth matter?

Frost depth is how deep the ground freezes. Footings and foundations have to extend below it so freezing soil does not push the structure around. The county lists 36 inches, which is one of the reasons new construction here requires careful planning. If you are buying land to build on, ask your builder how frost depth, soils and drainage affect your site.

What should land buyers do first?

If you are shopping for a lot in the unincorporated county, I like to see buyers handle these items during their due diligence period:

• Confirm jurisdiction. Is the parcel in the county or inside a town?
• Ask about access. Does a legal, maintained road reach the building site in winter?
• Plan for water and wastewater. The county does not issue well permits and has septic rules at sale; see my earlier guide on septic and wells in Gunnison County.
• Talk to a builder early. Local builders know what snow load, wind and frost requirements do to cost.
• Check covenants. Subdivisions can add design rules on top of the county's.

How do these requirements affect cost?

I cannot give you a price, because costs depend on design, site and season. In general, stronger roof framing, deeper foundations, quality insulation and good drainage are part of building well at this elevation. Ask builders to explain what is code-driven and what is a choice, and compare bids line by line.

What is the bottom line?

Snow load in Gunnison County is a site-specific number, not a one-size-fits-all figure. If you are building, start with the Building Office and a local designer. If you are buying, ask for permits, look closely at the roof and ask how the property handles winter. A good local agent can connect you with the right inspectors and builders.

Frequently asked questions

What is the ground snow load in Gunnison County?

The county says it varies by site and is based on the 2016 Colorado Design Snow Loads report; it does not list a single value.

How deep is the frost line in Gunnison County?

The county's design criteria list 36 inches.

What wind speed do new buildings need to be designed for?

104 mph (3-second gust, exposure C), per the county's page.

Where is the Gunnison County Building Office?

200 E. Virginia, Gunnison, CO 81230.

Connect with a great real estate agent in Gunnison, Kelsey Loftis with Crystal Peak Properties.