The rezoning of San Francisco’s Central SoMa neighborhood, a decade in the making, has always been about jobs — creating a place for the large-floor-plate office buildings that tech companies covet.

But as the South of Market plan heads to the Board of Supervisors for a vote in the next few weeks, Supervisor Jane Kim will introduce a set of amendments at Monday’s Land Use and Transportation Committee meeting designed to squeeze a little more housing out of the office-oriented rezoning.

Kim wants to change the zoning north of Harrison Street from “mixed-use office” to “mixed-use residential,” adding housing to that part of the plan’s designated area, which generally runs from close to Market Street south to Townsend Street and from Second Street to Sixth Street.

City planning officials say the change would result in about 250 more housing units and would mostly impact smaller sites north of Harrison Street.

“This will permit some housing on smaller sites — but not offices or hotels,” said Kim, who said she is trying to maximize the amount of housing in the plan without changing it so much that city planners would need to go back and update its environmental study, which could take two or three years.

Josh Switzky, who heads up community planning for the Planning Department, said that while the city has been working “seriously and diligently to expand housing in the city,” Central SoMa is the only plan left in the city where there is capacity to add jobs. He said the additional 250 units under Kim’s amendments are as much as can be added without prompting a new environmental study.

“It pushes about as far as we can push without disrupting the whole plan,” he said.

Originally, the plan envisioned 7,000 housing units and space for about 39,000 jobs. Gradually, city planners have been looking for ways to increase the amount of housing. Kim’s amendments would bring the housing unit count up to 8,550 housing units and the jobs down to about 32,500.

Kim said she wishes the jobs-to-housing ratio was more balanced.

“Of course, I wish I could go back in time and change it,” said Kim. “The city has changed tremendously over the last 10 years.”

The Central SoMa Plan was conceived before San Francisco had taken off as the global heart of the tech industry. While detractors charge that the plan would exacerbate the transformation of a once blue-collar neighborhood to a center of high-flying capitalism, proponents say the $2.2 billion in community benefits to be paid by developers make it worth it.

Those include about 2,700 units of below market-rate housing — worth $940 million — as well as 4 acres of open space. There’s also $25 million for the renovation and expansion of the Gene Friend Rec Center, a public swimming pool, and a new Flower Mart with permanently affordable rents. About $500 million in fees would be spent over 25 years on local and regional transit, $185 million for parks and recreation, $180 million for industrial space and $110 million paid to neighborhood nonprofits that work with social services and housing.

The plan is being appealed by the South of Market Community Action Network, or SOMCAN, a coalition of nonprofits and residents that opposes its focus on office space. SOMCAN planner David Woo said the plan will worsen “the disastrous impact that the policy of attracting tech companies has had on the working-class communities and immigrant communities in SoMa and across San Francisco.”

“We see the plan as a continuation of a gentrifying policy that creates a vision of San Francisco that is much more homogeneous in terms of race and class,” Woo said. “It will directly further gentrification and displacement, not just in SoMa but across the entire city. ”

SOMCAN wants the city to buy up rent-controlled buildings in the plan area, require that city-owned lots be developed with 100 percent affordable complexes, and require market-rate developers of sites of more than an acre to carve out a portion of the property for affordable housing. SOMCAN is calling for the housing in the plan area to be 50 percent affordable — the current plan calls for 33 percent.

Another group, the SoMa affordable housing owner TODCO, has also filed an appeal. Executive director John Elberling said Kim’s amendments move the plan in the right direction.

“What is going on right now, the Planning Department is finally trying to meet the community halfway,” Elberling said. “Now, we are finally talking about putting real teeth in the plan to achieve the community’s goals. ... Will it be enough? I don’t know yet. The proof is in the pudding.”

But Elberling said that some of the lots in the plan area currently slated for office buildings and hotels should be designated for more housing. TODCO is advocating for one amendment that would only allow affordable housing on existing parking lots and another that would require the city to use eminent domain to acquire vacant sites to build affordable housing.

In addition, Kim is proposing to cut the amount of parking in residential buildings in half, from .5 spots per unit to .25. Any developer wanting to go to .5 would have to get a conditional use approval.

“The whole plan is being built around the Central Subway — I don’t think we should be allowing more parking,” said Kim. “We already have congestion issues.”

Meanwhile, at least one SoMa property owner may be forced to rethink its plans because of the amendments. A New York partnership is proposing to build an 18-story, 200-room Citizen M hotel at 816 Folsom St., which would not be allowed under the new zoning. A spokesman for the developer declined to comment on the zoning changes because they hadn’t seen the amendments yet.

After the Land Use Committee considers Kim’s amendments Monday, the plan will go to the full Board of Supervisors for final approval, probably sometime after its August recess.

J.K. Dineen is a San Francisco Chronicle staff writer. Email: jdineen@sfchronicle.com Twitter: @sfjkdineen