Kennedy & Violich Architecture has enlarged a 1970s brick building at Harvard University by creating two new levels topped with a pitched roof.

Kennedy & Violich added two new storeys and an angled copper roof to Harvard's Tozzer Library, which has been renamed the Tozzer Anthropology Building.

Encompassing 35,000 square feet (3,250 square metres), the expanded building contains offices and classrooms for the social anthropology programme, along with a library for the entire anthropology department.

The project also entailed re-cladding and creating a new entrance for the three-storey building, which was originally designed by local firm Johnson Hotvedt and Associates and completed in 1974.

Print volumes in the library were digitised and moved off site. "This reduction in book weight freed up the structural capacity to support the two new floors of offices and classrooms above," the firm said.

The expansion increased the building's usable space by 29 per cent. The new levels are organised around an interior lightwell sheathed in birch wood panels, which reflect sound and light.

"Offices, classrooms and informal gathering places ring this 'living space,' which brings daylight into the building, and creates visual relationships between floor levels," said the firm.

The new copper roof that tops the structure is angled to direct daylight into the building.

The redesign preserved the building's foundation, infrastructure and its steel and concrete structure. Its brick cladding had to be removed, however, due to mould and vapour barrier issues.

The team re-clad the structure in wire-cut, iron-burnt brick.

"The main building is wrapped by 'thin' taught brick bands that express the existing slab, of which the new brick envelope is relieved," the firm said. "Vertical expansion joints are staggered between floor levels while horizontal expansion joints occur behind recessed solider courses."

The architects used bricks with a smoother finish for the new entry, a small volume attached to the rear the building and adjacent to a courtyard. Part of the structure is clad in corbelled brick, which was designed and tested using special software created for this project.

The new entrance bolsters the building's connection to the courtyard and two neighbouring buildings, the Harvard Museum of Natural History and the Peabody Museum of Archaeology and Ethnology.

"The massing strengthens a more independent reading of the Tozzer Anthropology building as a pavilion in the Peabody Courtyard," said the firm.

"The new design includes new landscape elements and grading of the Peabody Courtyard, as well as the design integration of archaeological photographs and artefacts."

Boston-based Kennedy & Violich Architecture was founded in 1990 and has designed a variety of projects – it also has a research lab called MATx which explores the sustainable use of new and existing materials.

Other recent projects at Harvard include the expansion of the university's art museum, designed by Renzo Piano Building Workshop.