SOUTH KINGSTOWN -- In a bid to increase the community's affordable housing, the Town Council this week approved zoning regulations requiring builders to include low- and moderate-income units in their development plans.

The move made the town the first in Rhode Island to adopt the measure as part of the new affordable-housing plans filed with the state, said Derry Riding, a principal planner with the Statewide Planning Program.

"Kudos to them," she said.

The council on Monday unanimously approved inclusionary zoning rules mandating that 20 percent of all subdivisions of six or more lots be affordable to people of low or moderate income. At least four units in a 20-unit project must meet those criteria.

In exchange, the developers will be granted density bonuses to offset the cost of building the affordable units.

The regulations apply to all major land development projects, including condominiums and senior housing complexes. All housing created under the regulations would have to remain affordable for at least 99 years.

"I think it's a good step," council President Mary "Polly" Eddy said yesterday. "I hope the builders come in and start building affordable housing."

The town's affordable-housing plan named inclusionary zoning as a key strategy toward increasing the town's affordable housing. The state requires that 10 percent of the units in each town be classified as affordable by 2025.

Currently 5.2 percent of South Kingstown's housing or 497 units meet the state's criteria, 459 units short of the goal. Low- to moderate-income housing must have a government subsidy -- which could include a density bonus -- to be considered affordable in Rhode Island.

While the regulations are being praised by town leaders and the planning community, the building industry's response was far from glowing.

"It looks on its face so easy and attractive that towns are drawn to it, " said Roger Warren, executive director of the Rhode Island Builders Association. Twenty-six communities are considering implementing similar regulations.

As written, the regulations would force developers and new homebuyers to bear the brunt of the costs of increasing affordable housing, he said.

"What we object to is the last people who have moved into South Kingstown ... are the people who are bearing the burden," Warren said. The related cost should be borne by the community and by the government, he said.

More dense development will only raise objections from would-be neighbors, who for years have associated housing with increased school costs, he said. The bonus is not enough to compensate for the subsidy the rules require builders to bear and will drive the cost of midrange houses up, he said.

"Every time you increase the cost of housing, you're pushing somebody out," he said.

Planning Director L. Vincent Murray says the regulations were crafted to give developers a reasonable return on their investment through the density bonuses.

"One of the efforts is to neutralize land costs," Murray said.

He looks to communities throughout the Northeast and California that have implemented similar rules.

"We're going down a new regulatory path for Rhode Island, but it's certainly not new," he said. "We're at a point of making change in our regulations because there is a problem. ... The nature of the need requires regulators to all do things a little differently."

Murray and Riding acknowledge that adjustments may need to be made along the way, but both say it's time to get going.

"We are where we are, and we need to be in a different place relative to housing," Murray said.

Riding plans to participate in a phone conference in the next two days about inclusionary zoning. It will be put on by PolicyLink, a national nonprofit that advocates for opportunities for low-income residents.

Information compiled by the group shows that inclusionary housing programs in California did not negatively impact housing production. Most communities saw an increase in housing construction, sometimes dramatically.

A national analysis by the group revealed that mandatory programs produce more housing that is voluntary, and that the trend was toward mandatory.

"It's going to take the communities all working together," Riding said. "As I say everybody's always nervous with anything new."

In the coming months, the Planning Board will adjust the subdivision regulations to reflect the new rules.