ROCHESTER — Mayo Clinic plans to spend $72.1 million to expand St. Marys Hospital in Rochester and make other renovations.

Five floors will be added to the Mary Brigh East building, and the third floor of the Domatilla building will be remodeled. Both projects will begin in the second quarter of 2014 and should be done by early 2016.

The clinic said the project will add 69

patient rooms with private bathrooms and space for family members to stay overnight. Expansion of surgical units on the East building’s first four floors is nearly done.

Mayo will save $1 million on the project because the construction crane currently onsite won’t need to be dismantled and rebuilt.

The expansion “supports the Destination Medical Center’s infrastructure,” the clinic said in a statement.