The Cambridge Housing Authority has awarded a $21.6 million contract to revitalize the 122-unit Putnam Garden Apartments.

Waltham-based CTA Construction received the contract for the project, which includes replacement of common stairwells, renovation of kitchens and bathrooms and installation of a new sprinkler system throughout the three-building complex.

Construction on vacant apartments and stairwells will be done in phases. Inside the units, the kitchens and bathrooms will be renovated with new finishes and fixtures, as well as work as needed on other features, including insulation, painting and baseboard heating. In addition, repairs will be made to floors, doorframes and windows. The entire plumbing system for the complex will be replaced, including new water lines run off of the city water mains.

In common areas, stairwells will be upgraded and a new boiler plant serving all three buildings will be installed. New sprinkler service and heating pipes, as well as central heat-recovery ventilation units and ductwork, will be installed in the basements. This will require demotion and asbestos abatement work to take place in the basements of each building.

The project also includes repairs to the roof to extend the manufacturer’s warranty and construction of four waste-management sheds with electrical and water service.

CTA previously renovated the Harry S. Truman Apartment Building for the Cambridge Housing Authority.