SAN JOSE — Amid the affluence of Silicon Valley’s highly paid technology employees, an “invisible workforce” of low-paid support staff at the region’s tech companies has emerged, making one-fifth the wages of the digital workers, according to a report released Tuesday.

Janitors, landscapers, grounds keepers, facilities cleaners and security guards working under contracts to provide support services to technology sites make about one-fifth the wages of software developers, systems software employees and network engineers, the study by a San Jose-based labor group, Working Partnerships USA, determined.

“Although the support staff goes to work each day on the same campus as the engineers and coders, their wages are worlds apart,” the group’s report says.

The low-paid contract employees make an average of $13 an hour — well below the $62 an hour for software and networking employees, the report found.

“This is a real problem,” said Russell Hancock, president of Joint Venture Silicon Valley, which tracks economic and employment issues in the Bay Area. “The high-skill tech jobs are becoming very high skill. That is really driving the wage gap. There are bidding wars for tech employees.”

Although a slew of diversity reports for high-tech companies in Silicon Valley have revealed a digital workforce that is dominated by white and Asian males, the Working Partnerships report found that high tech does have a racially diverse workforce on its campuses.

“The reality is that tech already employs the services of an army of Latino, black and immigrant workers: those who clean, guard, maintain, and cook on tech campuses every day, often for poverty-level wages,” according to the study.

Among computer and mathematical jobs in Santa Clara County, 88 percent offer earned sick days, and 85 percent of engineering and architecture jobs offer earned sick days, according to the report, which used Census Bureau and Labor Department official reports to compile the data. In contrast, 41 percent of building and ground cleaning jobs offer sick pay.

For every tech job created in Santa Clara County, four other jobs are needed to support that technology employee, the study estimated.

The wage gap comes at a time when prices for homes and apartments have soared in Silicon Valley and numerous other parts of the Bay Area.

“We are seeing rent increases throughout Silicon Valley, but we are not seeing a corresponding increase in wages,” Hancock said.

Contact George Avalos at 408-859-5167. Follow him at Twitter.com/georgeavalos.