Exposure C Wind Requirements for Lone Tree, CO Roofs

Lone Tree Roofing Co · Local roofing guide · Updated August 2026

Lone Tree asks every roof to be designed for a 115 mph wind gust across open terrain. That is the city's published design criteria, and it is stricter than the assumptions behind many standard shingle installations. If you are replacing a roof here, the wind numbers should shape the shingle class, the nailing pattern, and the edge details in your scope. Here is what the criteria say and what they mean on an actual roof.

Lone Tree's Roofing Design Criteria in Plain English

The city builds on the 2021 IBC and IRC family of codes with the 2023 NEC and local amendments, and publishes its design criteria for anyone to read. For a typical Lone Tree house, which the code treats as a Risk Category II building, the numbers that matter on the roof look like this:

One translation note. The 115 mph figure is an ultimate design speed, a rare peak gust that engineers design against, not a wind you should expect on a Tuesday. The roof assembly has to be built so that when that gust eventually shows up, the shingles, the deck, and the edges all stay where they were nailed.

What Exposure C Means on Lone Tree's Mesa and Bluff Terrain

Exposure categories describe how much the surrounding landscape slows the wind down before it reaches your house. Exposure B is the sheltered suburban default, wind filtered through trees and closely spaced rooftops. Exposure C is open terrain with only scattered obstructions, and at the same wind speed it produces meaningfully higher design pressures on a roof.

Lone Tree earns its C the honest way. The city sits on mesa-and-bluff ground at about 6,000 feet, and wind gets a long, uninterrupted run across the open grassland around Bluffs Regional Park and down the I-25 corridor. Homes backing to open space near the Bluffs trailheads, and the newer streets on RidgeGate's east side where open ground still outnumbers rooftops, feel that fetch directly. There is simply less in the wind's way here, and the code accounts for it.

Shingle Wind Ratings That Match Exposure C in Lone Tree

Asphalt shingles carry wind ratings from standardized tests, and the class printed on the wrapper matters. Under the common ASTM D7158 standard, Class D is rated to 90 mph, Class G to 120, and Class H to 150. For a 115 mph ULT design speed at Exposure C, the practical answer is a Class H shingle installed to its high-wind instructions. Plenty of mid-grade products already test to Class H; the failure point is usually the installation, not the wrapper.

Wind class is also a separate question from hail class. A shingle's impact rating covers hail strikes, not uplift, and the two ratings are earned in different tests. If you are weighing impact-resistant products anyway, the math lives on our impact-resistant shingles guide.

Fastening, Starter Courses, and Edge Metal for 115 mph Wind

Wind failures almost never start in the middle of a roof plane. They start at edges and corners, where uplift pressures peak, and they propagate. The details that hold a Lone Tree roof together are unglamorous:

• Six-nail fastening. High-wind installation means six nails per shingle, driven flush in the nailing zone, not four nails wherever the gun landed.
• Sealed starter at eaves and rakes. Real starter strip with the adhesive band at the roof edge, on the rakes as well as the eaves. Skipping rake starter is a classic shortcut on older installs.
• Edge metal, properly fastened. Drip edge secured to code spacing, because the perimeter metal is the first thing a gust tries to peel.
• Rated hip and ridge caps. Ridge caps take the highest wind on the roof; they need to be a rated product, not cut-up field shingles.
• Underlayment and ice barrier. The 2021 IRC's ice barrier provision applies unless amended locally, so plan for ice and water shield at eaves and valleys and confirm specifics with the Building Division at 720-390-5211.

How to Ask for the Wind Spec in Your Lone Tree Roofing Scope

A written scope should answer four questions without you chasing anyone: what wind class the shingle carries, what nailing pattern is being used, whether eaves and rakes get sealed starter, and what edge metal is included. If a bid cannot answer them on paper, that tells you how the roof will be built. Our scopes state all four; our roof replacement page shows how we build to them.

Lone Tree Wind Rating FAQ

• What wind rating do shingles need in Lone Tree? The city's design criteria call for 115 mph ultimate design wind speed at Exposure C for typical homes. In practice that points to a Class H shingle under ASTM D7158, rated to 150 mph, installed with six-nail high-wind fastening and sealed starter courses at both eaves and rakes.
• What does Exposure C mean for my roof? Exposure C means open terrain with scattered obstructions, which lets wind hit a roof harder than in a sheltered suburb. Lone Tree's mesa-and-bluff geography and the open fetch near Bluffs Regional Park and the I-25 corridor put homes in that category, so fastening and edge details need to be built for higher uplift pressures.
• Does Lone Tree really get 115 mph winds? The 115 mph number is an ultimate design value, a rare peak gust engineers design against rather than a routine forecast. Front Range downslope winds do produce strong gust events, and the open ground around Lone Tree gives them a clean run, so the code sets the bar high on purpose.

Not sure what class of shingle is on your roof now, or how it was nailed? A free documented inspection answers both with a written photo report and a written scope. Schedule yours here.

More Lone Tree Roofing Guides

• Hail-Resistant Materials
• Stone-Coated Steel Roofing
• City Roof Inspections