Needham-based Nauset Construction has begun work on a new memory care wing at the Nashua Crossings senior living community for Benchmark Senior Living in Wellesley.

The 14,675-square-foot, one-story addition will provide 20 new rooms specifically designed to care for seniors with memory impairment issues and will be comprised of one and two-bedrooms with a number of handicap-accessible units. The addition will also house a nurse station, living room, dining room and two exterior courtyard areas with porches for the residents. Construction is expected to be completed by spring 2014.

The existing community at Nashua Crossings was built in 1999 on a 3.5-acre parcel at 674 West Hollis St. and currently houses 64 assisted-living units. Designed by New Hampshire-based architects Udelsman Assoc., the new memory care addition will be a wood-framed structure featuring wood trusses with vinyl siding and asphalt roof shingles.