TAMPA - Neighborhood activists and builders know that when a new development is planned for a part of town, the project can't have more housing units than what the zoning allows.

Now Tampa is looking at turning that concept upside down by regulating the minimum number of units allowed. The concept is known as minimum zoning, and if Tampa were to adopt that philosophy in its comprehensive plan, the city could be the first in the state to do so.

The planning tool is lauded as a way to encourage transit and a way to better prepare for an influx of people, but it is sharply criticized as a threat to neighborhoods and property rights. With that in mind, city planners last week decided to hold off recommending to the city council that they include minimum zoning requirements in the city's long-range comprehensive plan.

Yet city officials say they will further study minimum zoning to decide whether it could work in Tampa.

"We do recognize that minimum density is one of the characteristics used for transit-oriented development," said Cyndy Miller, the city's director of growth management and development services. But, she said, the city still has time to see whether it's the best approach.

Minimum zoning requirements could push people into certain parts of town ripe for transit.

Terry Cullen, team leader for urban planning for the Hillsborough Planning Commission, said projections show Tampa will gain 92,000 residents and 132,000 workers in the next 20 years.

"The city of Tampa doesn't have a whole lot more room to grow other than the boundaries it has now," Cullen said. "Where are you going to put all the people? We're looking at the future. The idea is you want to use your land more efficiently, it gets you ready for transit."

Under a minimum zoning concept, in some parts of the city developers would be required to build at least 15 units per acre.

"That kind of development supports transit," Cullen said. With minimum density requirements, the city could direct development - meaning residents and workers - into areas where transit stations are likely.

The effects, he said, would likely be felt more by developing areas, such as Central Park Village, Tampa Heights and the Channel District, rather than well-established neighborhoods.

Still, neighborhood leaders don't like the idea. Wofford Johnson, president of Tampa Homeowners, an Association of Neighborhoods, said his group opposes minimum density requirements.

"Our concern is that in many neighborhoods, this would lead to increased density that perhaps the neighborhood and the infrastructure can't support," Johnson said.

Developer Spencer Kass also has been vocal in his opposition.

"I'm not opposed to density," said Kass, owner of Landmarc Reality. "I'm opposed to being told I have to do it."

His offices, he said, are 2,000 square feet. But, he said, if minimum zoning requirements had been in effect, he would have had to build 4,000 square feet to meet the rules in his North Howard Avenue neighborhood. That would have dramatically increased his expenses.

Council members also are slow to support the concept.

Councilman Mary Mulhern said offering incentives for denser development would be a better approach.

Councilman John Dingfelder, too, would prefer offering more incentives to developers who want to build denser projects. He is concerned that mandating a minimum density runs afoul of property rights.

"Every now and then, something doesn't pass the smell test, and that didn't pass the smell test to me," he said.

For now, then, the city will hold off but will study the subject. Cullen, from the planning commission, says something needs to be done.

"A lot of people will say we don't want that growth," Cullen said. "The growth is going to come. We need to be ready for it."

Reporter Ellen Gedalius can be reached at (813) 259-7679 or egedalius@tampatrib.com.