To protect the building and its documents from damage in a major earthquake, the government became interested in designing the building with a steel structural frame. The global construction industry had been revolutionised in the mid-19th century with the introduction of the Bessemer process, which made great quantities of cheap steel available; however, no previous building in New Zealand had been designed with a steel frame. In 1904 the government contracted the services of San Francisco architects Messrs Reid Brothers for a princely sum of £1400 to provide their expertise on the design and construction of a steel rivet frame (rivets were used to connect the members of a steel frame before bolts and modern welding techniques were invented).

James, Merritt and Watson Reid were born in Canada and trained in America before setting up an architectural practice in San Francisco that developed into one of the largest architectural offices in the United States. Their knowledge and experience would have been invaluable to Sir John Campbell in designing the Old Public Trust Building.

Local controversy and a missed opportunity

The decision to contract Messrs Reid Brothers was highly controversial. The Chronicle newspaper reported the transaction as "£1400 thrown away!" Letters to the newspaper complained about extra delays and the high cost, and questioned the ability of steel frames to resist earthquakes. However, the government was committed to the idea and the building became the first in New Zealand to be designed with a steel rivet frame.

In Wellington, John Campbell was probably assisted by architect Thomas Turnbull. Turnbull was born in Glasgow and practised as a prominent architect in San Francisco before emigrating to Wellington in 1871. In New Zealand, Turnbull was a pioneer in earthquake construction, advocating a shift from timber buildings to more permanent materials like masonry. His experience would also have been useful to Sir John Campbell while designing the Old Public Trust Building.

Earthquakes shake Wellington and its regions

In 1923 Wellington was rattled by a sharp earthquake. The Old Public Trust Building appeared to suffer only minor cracks to its plaster. However, one weekend in 1926, a girder in the Legal Branch broke loose and crashed to the floor - luckily nobody was at work at the time. An engineering assessment determined this was caused by damage from the 1923 earthquake and staff were instructed not to sit under the girders until strengthening work was completed in 1927.

In 1942 Wellington was hit by two severe earthquakes centred in the Wairarapa. There was extensive damage throughout the city but amazingly the Old Public Trust Building suffered only minor plaster cracks - attributed to the deliberate and acceptable movement of the building's expansion joints.

Recent earthquake strengthening work

In 1983 Riddiford Holdings started an extensive earthquake re-strengthening project to bring the building up to contemporary Wellington City Council standards.