Gelwicks said it took about 40 firefighters from six companies about an hour to bring the flames under control.
The cause of the blaze was listed as an oil furnace malfunction.
Gelwicks said firefighters prevented the blaze from spreading to the rest of the complex, located on Oak Springs Road south of the airport. A passerby on nearby Pennsylvania Avenue called the fire in, he said.
Authorities estimated damage to the building at $200,000 and to the building's contents at $250,000.
Gelwicks said from $2 million to $2.5 million worth of property was spared because of firefighters' quick action.
"We're always telling people how much was lost," Gelwicks said. "We figured, let's let them know how much was saved."
Thurman S. Alphin, who owns the business, said the company will be able to conduct most aspects of its work, including the repair of planes and plane parts.
He said the company would set up a temporary facility for paint jobs.
Alphin said he checked in on the shop before he left at about 8:30 p.m. Monday.
"I checked to make sure the paint shop was locked," he said. "I didn't look inside, but I checked the lock."
His son, T.L. Alphin, said he increased the company's insurance coverage about 4 1/2 weeks ago.
"It's a good thing I upped the insurance," he said.
Alphin had just completed painting an airplane belonging to an air club in Virginia, he said. Gelwicks said the plane was destroyed in the fire.
"About all that was left was the propeller and engine," he said.
Alphin said he began rebuilding airplanes in his spare time after working for Fairchild Industries in the 1940s. He opened the company in 1959 and moved to the current location in 1966. He said the paint shop was completed in 1968.
He said the company employs 32 or 33 people.