April 25– Apr. 25–Plans to convert the historic Hearst Building into a hotel in downtown San Francisco won approval Thursday from the city's Planning Commission.

Developer JMA Ventures and property owner Hearst Corp. want to convert offices in the 1909 building at 5 Third St. into 170 hotel rooms. The project would add a new rooftop bar, event spaces and seismic upgrades, while preserving the lobby designed by architect Julia Morgan. The project requires final approval from the Board of Supervisors.

The developer is working with existing retail tenants to either honor leases or find alternatives, Todd Chapman, president of JMA Ventures, said at Thursday's Planning Commission hearing.

Hearst Corp., which also owns The Chronicle, referred requests for comment to Chapman.

An agreement is expected within weeks between the developer and Local Edition, the popular basement bar in the building. If construction moves forward, the bar would have to temporarily close for around 18 months, said Chapman. "We understand there will be some disruption," he said, but plans call for the bar to return.

Brian Sheehy, co-founder of Future Bars, which operates Local Edition, said under the proposed agreement, the developer and building owner would cover any "displaced income" for up to five years.

Two ground-floor tenants also operated by Future Bars — the Lark bar and spirits shop Cask — plan to relocate next door to the Monadnock Building at 685 Market St. That building has an empty retail space on Market Street that was last occupied by Jeffrey's Toys four years ago.

Planning commissioners said they supported the hotel project because it would help enliven the street and preserve a historic building.

Built in the aftermath of the 1906 earthquake, the Hearst Building was originally the office of the San Francisco Examiner. It was part of the "Newspaper Angle" that included the former offices of The Chronicle and defunct San Francisco Call. (Hearst Corp. bought The Chronicle and sold the Examiner in 2000.)

Other historic office buildings are turning into hotels. Yotel opened in the former Grant Building earlier this year, and building permits have been filed to convert a 1922 office building at 425 Mason St. near Union Square into hotel.

Roland Li is a Chronicle staff writer. Email: roland.li@sfchronicle.com Twitter: @rolandlisf