SALISBURY — A restoration specialist with the N.C. State Historic Preservation Office gave some guidance on substitute materials to Salisbury’s Historic Preservation Commission on Thursday afternoon.

Brett Sturm’s presentation was titled “History in the Making, or an Assault on Good Taste?”

The commission has been challenged on several cases involving roof replacements and rejected some applicantions because the proposed substitute materials were not in line with the commission’s guidelines. Several applicants have argued that replacing a roof with the same materials would be an economic burden on them, but the commissioners said they cannot consider cost in approving permits.

Sturm started by showing four buildings: South Philadelphia rowhouses; the Wrigley Building in Chicago; Victoria Mansion in Portland, Maine; and the Redwood Library and Athenaeum in Newport, Rhode Island.

“What did they all have in common?” he asked the commissioners.

He responded that all made good use of substitute materials.

He cited a preservation guideline that states: “In limited circumstances, substitute material may be used if the appearance and properties of the historic material can be matched closely and no damage to the remaining historic fabric will result.”

Limited circumstances include that the historic material is no longer available; craft techniques or skilled artisans are no longer available to duplicate the historic material; the original historic material was inherently poor; and code-related changes dictate new material properties, according to the brief.

Several commissioners said that in their opinion, property owners can always find the material, even if it comes at a higher cost.

Jon Planovsky said the materials can be re-created, and that’s the source of the commission’s confusion.

Sturm said there are a lot of gray areas.

“If you read the standards, they are all so vague, because every building has its own unique spacial, historical context, and I think as a field we need to avoid black and white,” Sturm said.

He said members of the commission should be good actors in the community and acknowledge the cost of materials. He said that can be done by educating the community or directing applicants to the State Historic Preservation Office.

Commissioner Acey Worthy said denying a permit may mean a house is pushed in a downward slide.

Sturm recommended that the commission pick its battles. He showed several homes and asked whether the board would allow a roof replacement with different materials. He pointed out the commission is likely to see an increase of requests for roof replacements because slate roofs typically last 90 years and are a feature of the early 20th century. He also said metal shingle roofs, which are common in Salisbury, are aging out.

He advised the commission to ensure “the roof really is toast,” consider how prominent the roof is to the property and how good a match is presented.

Commissioner Elizabeth Trick said some applicants don’t take into account that a higher price for a new roof typically means a longer lifespan.

Commissioner Will James said he would like the State Historic Preservation Office to take into account that the homes the commission sees are not “Mount Vernons” but instead on a Main Street setting. He asked for some guidance on how to handle properties that have less historical value.

Chairman Andrew Walker said the commission members should consider whether they want Salisbury to be museum quality.