The Roxbury Market & Deli could be about to grow.

Owners Thomas Thorne and Robert Burmann received a certificate of appropriateness Dec. 15 from the town's Historic District Commission to increase the building's size by nearly 20 percent of its present footprint.

By the next day, their application had been submitted to the town's Inland Wetlands office.

The proposal is to construct a 1,908-square-foot addition to the south side of the circa 1935 structure.

"We'd been over a series of plans with the owners of the market and their architect," said Wendy Walker, chairman of the Historic District Commission, "and reached the decision that the design fits in proportion and style in the historic district."

The addition would provide more space for Union Savings Bank, located in the south end of the structure.

The commission agreed in the plan to a single drive-up window in the rear of the building and an ATM.

"Union Savings spoke to us about enlarging their present area and we said we'd attempt to," Mr. Thorne said.

"At this time, the bank has just 600-square-feet," he noted. "There is no room for privacy in discussions with customers on financial matters."

Mr. Thorne said the addition would also be an improvement for customers wanting to access the property.

The Post Office loading dock, now in the front of the building, would be relocated to the building's rear.

"Big trucks coming in mid-day now to pick up and unload mail are a real obstacle to customers wanting to access the deli and the bank," he said. "A drive-up window in the rear of the bank, would be an improvement for older and handicapped bank patrons."

There is obstacle to the addition, however.

As Roxbury's zoning regulations stand, expansion would not be allowed for a "legal, non-conforming structure," and the market building falls under that category.

A zoning regulation change would therefore have to occur. At that point, a special permit for the addition could be considered.

Mr. Thorne has been in pre-application discussion with the commission.

Mr. Thorne and his brother-in-law, Mr. Burmann, purchased the building in 2000.

In 2004, they were denied a variance by the town's Zoning Board of Appeals to expand the Post Office.

Mr. Thorne said the rejection was due to insufficient paperwork from the Postal Service.