The Presbyterian Church is to buy the Four Seasons care home in Garvagh to create a new residential home for older people.
The £1.5m redevelopment of the home will increase overall places to 50 en-suite rooms.
It will also involve the relocation of services from its Londonderry and Portrush residential care homes, Ard Cluan House and York House, which will be sold.
The new home will be able to care for residents with dementia.
Healthcare union Unison says its members at the two existing homes are concerned about whether they can relocate to Garvagh and potential travel costs.
Lindsay Conway, of the church’s Council for Social Witness, said: “Due to changing legislation, increasing standards and rising expectations of residents and their families, we review aspects of our service provision regularly.
“This ensures our residents across all of our homes are provided with the best care. Unfortunately, Ard Cluan and York House, which were both built in 19th century, no longer provide the opportunities for improvement.”