In the late 1860s Dockery built a brick kiln near Middle Creek outside Sevierville and established a brick masonry business. Dockery inscribed his initials, I D, and sometimes a date, on his bricks as a trademark. A master brick mason, Dockery taught his craft to his sons, his sons-in-law, and his grandsons.
Dockery made the bricks for several notable Sevierville landmarks, including the Murphy College building (1891), the Sevierville Masonic Lodge (1893), and the Sevier County Courthouse (1896). He also built at least two commercial buildings on the original public square which were destroyed in a 1900 fire. The New Salem Baptist Church, built in 1886 for the local black community, remains his most significant building. This handsome Gothic Revival-style church was originally constructed as a Union Church, which welcomed all religious denominations. The New Salem Baptist Church is the oldest remaining building in Sevierville and the second oldest church building in the county.
Several members of Dockery's family also became well-known brick masons in Sevier County, including Paris Witt McMahan, George and Stewart Burden, Bill Coleman, and Fred McMahan, who established the J, F & N McMahan Construction Company. Dockery died in 1910 at his son's home in Knoxville. He was buried in the Public Cemetery for African Americans near Sevierville.