The Beaver Creek Fire has now burned 11,776 acres and has crossed into the Mount Zirkel Wilderness.
Thick forest and beetle-killed trees are helping fuel the wildfire burning between Walden and the Colorado-Wyoming border.
U.S. Forest Service spokesman Aaron Voos told the Steamboat Today that the fire could burn for some time. The fire is only 5 percent contained and full containment isn't expected until Aug. 1.
Firefighters on Tuesday burned areas between structures to improve the ability to defend them. Crews also removed grass and other flammable materials from around buildings and utilized sprinklers, according to the Forest Service.
Tuesday, crews worked along Forest Road 600 to defend buildings. Wednesday, a second structure protection group will continue work in Parsons Draw.
The cause of the Beaver Creek Fire remains under investigation.
Smoke from the fire has spread east and created haze along the Front Range.