The November sting began at a house in San Rafael, where investigators posing as homeowners sought bids on various jobs ranging from landscaping to concrete work and painting.

Enforcement operations are held throughout the state on a weekly basis. The purpose is to bring contractors into compliance and to make consumers aware of the dangers of hiring unlicensed workers.

Ted Van Midde, a San Rafael concrete contractor and past president of the Marin Builders Association, said these operations are important because licensed contractors, who pay taxes and carry the proper insurance, cannot compete with unlicensed operations that typically pay workers in cash to avoid paying taxes and insurance.

“Unlicensed contractors can give bids that are 30 percent lower,” Van Midde said. “If something goes wrong with the job, a consumer has no recourse.”