A high school dropout who became a billionaire roofing company executive and one of the nation's richest people died Friday after falling through his garage roof.

Ken Hendricks, who was 66, was the 91st richest man in the U.S. with a net worth of $3.5 billion in September, according to Forbes magazine.

Hendricks grew up working side-by-side with his father, a Janesville roofer. After dropping out of high school, he started his own roofing business at age 21, according to a biography supplied by his company.

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Tired of dealing with multiple suppliers scattered around the country, he and his wife, Diane, started a national supply distribution chain in 1982.

ABC Supply Co. - based in Beloit, Wis., about 60 miles southwest of Milwaukee - celebrated its 25th anniversary this year, with 6,000 employees in 390 locations nationwide. It does about $3 billion in business a year.

Hendricks was unfazed by his wealth.

"It doesn't make any difference to me: I can't spend it," he said in an interview with Inc. magazine in September 2006. "I'd have to sell the company, and I'll sell the company over my dead body."

Hendricks was checking on construction on his garage roof in the town of Rock about late Thursday when he fell through, Rock County Sheriff's Department commander Troy Knudson said.

He suffered massive head injuries and died in surgery Friday at Rockford Memorial Hospital in Winnebago County, Ill., according to his company and county authorities.

Hendricks was lauded for his entrepreneurial skills and community service.

Inc. magazine named him its 2006 Entrepreneur of the Year. Editor Jane Berentson described him as "a scrappy, Midwestern dirt-under-the-fingernails type of guy who raised himself and created a company that employed all these people."

Hendricks was unpretentious, a believer in hard work and doing things his way, she said.

Hendricks and his wife also owned a property development group with more than 25 million square feet of industrial and commercial real estate. They worked to renovate buildings made vacant by other companies.

He also was known for having a common touch. He wore blue jeans and cowboy boots to a 2005 interview with a local newspaper and talked about how he enjoyed driving his Jeep Grand Cherokee.

Berentson said he told her magazine last year that one of his most rewarding moments came at an annual managers meeting for ABC Supply.

"I gave my motivational talk and then I asked, 'How many people here started as a forklift operator, a warehouse person, a roof loader, or a truck driver?"' he said. "We had 600 people and almost half of them stood up."

Hendricks is survived by his wife and seven children.

