SCARBOROUGH, Maine — Planning board members on Monday continued to weigh the use of incentives to preserve nearly 50 historic properties across town. The board also discussed a revised plan to expand the Piper Shores retirement community.

No action was taken on either issue.

Unlike several towns, which dictate the structure, aesthetic touches and even shingle design of buildings in historic zones, Scarborough is considering a “carrot-based approach,” according to board Chairman Cory Fellows.

The historic zoning provisions would be based exclusively on incentives, Town Planner Dan Bacon said.

Under proposed zoning amendments, owners of 48 structures would receive a “residential density credit that enables a developer to get ‘credit’ for preserving a historic building and surrounding lot,” according to an outline written by Bacon and presented at Monday’s meeting.

For example, if a preserved building is part of a proposed subdivision, the number of dwelling units allowable in the subdivision would be increased by the number of units within the historic structure.

Other incentives include exemptions from building and fire protection codes that could compromise a structure’s historical integrity. Such exceptions can “practically and economically help with the rehab of a historic building” and help to “maintain some of its historic character,” according to the outline.

While the board generally agreed that the provisions were a good idea, a few members criticized that they weren’t specific enough. For example, could someone “knock down [one of the historic] buildings without repercussions?” board member Ron Mazer asked.

Bacon said yes, but there will be an additional step added to the process, as is the case with other historic structures in the town.

“You need to demonstrate to the planning board that you did consider historic preservation and that you’ve taken steps to see if that’s possible,” Bacon said Tuesday. Once that’s considered, a building’s owner would be free to demolish the structure.

Otherwise, there’s no “mandate or requirement,” he said.

Piper Shores

The board was presented with a revised sketch plan of the proposed addition to the retirement community, which would include nearly 22,000 square feet of new space.

The facility, located off Piper Road, currently offers 160 independent living apartments, 20 assisted living units, 40 nursing rooms and 40 independent cottages.

The proposal includes a three-story addition to the northern wing of the Holbrook Health Center. Ground-floor parking would occupy the first floor, 14 memory care units would be installed on the second floor and 16 assisted living units would be added on the third floor.

The plan also proposes a 3,000-square-foot arts building, separate from the main facility.

The new construction would take place “almost entirely within existing developed area and will only result in modest increase in impervious area,” according to a letter by Michael Tadema-Wielandt, senior engineer for Fay, Spofford & Thorndike.

The proposed plan “does not include expansion on conservation land,” he told the board.

Board members seemed to regard the plan favorably but suggested moving a proposed community garden from the parking area, where it might be a safety hazard.

A site plan of the proposal likely will be presented to the planning board by the end of March or early April.