Christchurch's main Music Centre building will be demolished, with fears for valuable instruments and extensive music libraries trapped on the site.
Music Centre of Christchurch manager Bronwyn Bijl said two of the centre's four buildings had sustained significant earthquake damage.
The three-storey main building, a former convent, would be demolished, while the future of the chapel, which held the best Steinway grand piano in Christchurch, was uncertain.
Two other buildings, the hostel and portery, had received yellow stickers, but would not be used for the rest of this year.
Bijl was not sure whether the contents of the main building could be retrieved before it was demolished.
However, some items had been recovered from the yellow-stickered buildings.
Bijl said the music centre would reopen.
It was hoped to rebuild on the existing site.
Hundreds of people had attended music lessons at the Barbadoes St centre each week. The site was also used for rehearsals, performances and music exams.
Christchurch pianist Chris Graham has two pianos, including one that has been in his family for three generations, inside his third-floor studio.
He also has more than 1000 music books - collected over more than 30 years - in the studio.
"It's quite devastating to my living," he said.
Graham said he had insurance, but it would take almost 20 years to replace his books.
The centre, owned by the Sisters of Our Lady of the Missions and run by a trust, had 20 tenants, including the Christchurch School of Music, private music teachers and Trinity College.
More than 1100 music lessons were taught each week at the centre and 1900 events were held there last year.
Christchurch School of Music acting musical director Neville Forsythe said the impact of the centre's closure had been severe.
"It was our home, our office, our library and our instrument store," he said.
The school has up to 200 instruments inside the building, including some that would be difficult to replace like a 1.8-metre recorder and set of recorders that were replicas of ones used during the reign of King Henry VIII.
The most significant loss to the school was its library, which held thousands of music pieces for orchestras, choirs and chamber groups.
"It's a huge resource and it's trapped," Forsythe said.
The school had about 800 students attending weekly classes taught by 80 teachers at the Music Centre and the adjacent Cathedral College.
Those classes were now being held at Christchurch Boys' High and Rangi Ruru.
Cathedral of the Blessed Sacrament musical director and Christchurch Boys' High School music head Don Whelan said the cathedral choir also had a music library stored at the centre.