A new and more affordable era of development may be coming to one of Pittsburgh’s most rapidly changing neighborhoods.

Just before 5 p.m. yesterday, the Pittsburgh City Planning Commission voted unanimously to recommend an 18-month trial run for inclusionary zoning rules in Lawrenceville.

The legislation was introduced earlier this year by Council member Deb Gross, who represents Lawrenceville along with several other East End neighborhoods.

Under the proposed rules, any new residential developments in Upper, Central or Lower Lawrenceville with 20 or more units must rent at least 10 percent of the building as affordable housing.

The next and potentially final step will be a vote in City Council sometime in the next few weeks, where it is likely to pass. Along with Gross, Mayor Peduto and several other members of council have signaled their support for the program.

If approved, Pittsburgh City Council will have the power to extend the program beyond its initial 18 months. After the pilot concludes, the Planning Commission and City Council will study the results and use them as the basis for a permanent law.

Speaking before the commission on Tuesday afternoon, Gross said that the neighborhood’s rising prosperity had led to a significant drop in the amount of affordable housing available to long-time residents.

“This really is a crisis,” she said. “It may not be the right tool for every situation, but for Lawrenceville right now this is the tool.”

The new laws will not apply to developments already underway, and the draft of the program presented before the committee said landlords would be allowed to reserve the upper floors of their buildings for market-rate units.

While the new policies have significant support from many residents and community groups, experts from the Department of City Planning noted that during the public comment period for local landowners they received 168 statements in favor and 183 opposed. Many of those opposed cited concerns about the rules discouraging new development.

In her own remarks, Gross said the new zoning laws would ensure economic diversity and would make both Lawrenceville and the city stronger as a result.

“To lose your neighbors around you is really distressing,” she said. “I think it would be negligent of us to allow it to become a neighborhood of concentrated wealth.”