The Solomon R. Guggenheim Museum in New York, clad with scaffolding for nearly three years while engineers studied Frank Lloyd Wright's design, will be renovated by 2009, the foundation announced on Wednesday.

The distinctive spiral-shaped museum has suffered cracks on its external walls and other structural defects such as corroding steel supports and non-thermal windows.

Architect Frank Lloyd Wright looks over his spiral-shaped design for the Guggenheim Museum in New York in 1945.
(Associated Press)

But the Guggenheim Foundation said that restoration work could go ahead and the museum should be ready in time for its 50th anniversary celebration in 2009.

The museum will remain open throughout the $29-million US renovation.

"Frank Lloyd Wright, who was always at the cutting edge of technology and frequently ahead of his time, is also notorious for the failures of his buildings, often structural in nature," Pamela Jerome of Wank Adams Slavin Associates LLP, one of several firms that assessed the building.

The Guggenheim was one of the earliest buildings to be covered in sprayed concrete — which gives it its smooth curves. But expansion and contraction due to weathering has cracked the exterior.

The restoration experts have had to innovate to find materials that would look similar and expand and contract without causing damage, she said.

Some of the problems with the building is in the execution, as contractors skimped on steel supports on one of the upper ramps.

"Although some remedial reinforcing is necessary, our investigation revealed that Wright's radical design for the Guggenheim was irreproachable," Jerome said.

Care was taken to preserve historic elements of the museum, including Wright's design for windows and skylights, which will be replicated with thermal glass.

"From a preservation point of view, you don't want to change the external appearance," said Robert Silman, president of Robert Silman Associates, the project's structural engineers.

The cooling systems, elevators and bathrooms will also be upgraded, often with technology that didn't exist when Wright was designing.

Wright was an early adopter of new construction methods and materials so it is believed he would approve of the use of new innovations, the foundation said in a statement.

The interior of the museum, where visitors walk down the spiral as they view the art, was restored in 1992.

The Guggenheim Foundation, founded by art collector Solomon Guggenheim, also built the Frank Gehry-designed museum in Bilbao, Spain. 

With files from the Associated Press