Brent and Lindsey Sainsbury recently outfitted the back roof of their historic University Heights home with 22 photovoltaic (solar) panels. The couple were able to accomplish more with the project while spending less out of pocket thanks to a tax credit that helps owners of historic Wisconsin properties to keep these houses in good shape.

“It’s my philosophy to get as much green energy as possible,” said Brent Sainsbury, who owns the eco-realty firm Enlightening Real Estate in Madison. “The historic tax credit allowed me to put up more solar than I would have otherwise.”

The green-energy upgrade on the Sainsburys’ two-story Regent Street house, built in 1916, also covered some electrical fixes. Theirs is among 16 properties in Madison that have qualified so far this year for a historic home owner’s tax credit through the Wisconsin Historical Society’s Division of Historic Preservation. Last year, about 45 properties in the city were approved for a credit, said Mark Buechel, senior preservation architect with the historical society. While construction as a whole has suffered a downturn, projects to refurbish historic properties continued to be popular in the past two years.

Credits go for projects costing $10,000 or more on homes deemed historically significant (most are listed on the national or state historic register). The program offers qualified homeowners 25 percent tax credits on approved work.

The credit has two primary qualifying factors, according to Jim Sewel. The first: owning a historic property; the second: doing work that qualifies under credit rules. Sewel, a preservation consultant with James A. Sewell Preservation Services in Madison, helped create the program in the 1980s and upgrade it in 1992, and has administered it through the historical society until earlier this year.

There are three ways that properties can be identified as historic: location within a registered historic district, having an individual listing on the state or national historic register (the Robert La Follette house in Maple Bluff, for example), or having a house that qualifies for one of these registers, but has not yet been listed. All documentation forms and program guidelines are available on the historical society’s Web site.

“If you can make a case that it fits the criteria and the state historic society agrees, then you qualify for the tax credit,” Sewel said. “The application process or verification process for historic status is very simple.”

Once you know your home fits the historic home definition under the program, work you’re doing needs to be pre-qualified. The project needs to cost at least $10,000 and fit under five categories: exterior (which includes roofs, exterior painting, porch repair and woodwork fixes), plumbing (excluding cost of any fixtures), electrical rewiring (again, fixtures don’t qualify), mechanical systems (furnaces, water heaters and air conditioners), and structural repairs. Projects can be combined to meet the $10,000 minimum spending threshold, but work must be completed within two years; if needed, homeowners can apply for a five-year phased project.

Richard and Suzanne Linton refreshed the exterior of their Spaight Street Prairie Style house located in the Orton Park Historic District sooner than expected using higher-quality period-color paint thanks to the credit.

“Our goal was to not only protect the house (what paint is supposed to do; the old was not only unappealing, it was peeling) but to select colors that were more in keeping with the age and style of the house,” Linton said of the off-white color they eventually chose.

Because the dollar threshold is high, many qualifying projects are for roofing work, furnace replacement and other bigger ticket repair and replacement.

“This is for larger maintenance or larger rehabilitation projects,” Sewel said. “It’s (the society’s) way of encouraging owners to do exemplary work on their historic property.”

It’s also essential that the work proves compatible with the historic nature of the property. It must not diminish the historic character of the house, Sewel said, and therefore must be approved beforehand by a preservation architect at the historical society.

What is and what is not a good example of historical compliance? New roofing that replicates old weathered wood shingles in color and appearance is favored, rather than shingles that are not applied in a straight line, or with dark or irregular shadow lines, often called “drunken” shingles. Windows — often a significant contributor to the historic quality of a house — are often targeted for replacement. But new windows need to keep their historic character and it often needs to be proven that the old windows simply cannot be repaired.

Other things that do not qualify: insulation, interior remodeling and decoration, new additions, landscaping and other site work, and work on additions or out buildings that do not contribute to the historical significance of the property.

Buechel said the society approves about 240 projects statewide each year that result in some $6 million in rehabilitation work eligible under the credit program. Since 1992, when the program was launched in its current form, there have been some 2,500 projects and $63 million in eligible rehab work.