US-based sandwich chain Potbelly has signed a 20-unit deal with Sound Sandwich to expand the brand’s footprint in the greater Seattle-Tacoma region of Washington state.

The franchise deal includes a transfer of ownership of nine existing units and the development of 13 new restaurant venues in King, Pierce and Thurston counties over the next eight years.

Sound Sandwich is led by local franchisee partners. Its business model is focused on singular brand focus and growth informed by actionable data.

Potbelly president and CEO Bob Wright said: “We’re thrilled to put the Potbelly experience within the reach of more people in the Seattle-Tacoma region.

“This is a market that performs well but is significantly underpenetrated right now. We see tremendous whitespace for our brand and look forward to supporting our franchisee as they open the doors to new shops in the years ahead.”

The sandwich chain has also set a target to open 2,000 restaurant units under its ongoing Franchise Growth Acceleration Initiative.

Potbelly Franchising senior vice-president Lynette McKee said: “It’s always a pleasure working with proven franchisees that share our excitement and vision for the Potbelly brand.

“We are excited about the great potential this agreement offers us and we look forward to working closely with such a fantastic partner to continue our growth momentum in Washington state.”

Last month, Potbelly signed a 40-unit agreement with the Royal Restaurant Group.

Under the agreement, 36 new restaurant locations will opened in Ohio and Florida. It has also agreed to acquire four units in Ohio's greater Columbus metropolitan area.