The corrugated iron walls of Pier 8/9 at Walsh Bay have survived 80 years of hard knocks and harsh maritime conditions. Conservator Dave McBeath has just finished working on their conservation. He described the project at Any Old Iron, last month's seminar on corrugated iron organised by the Heritage Council's Technical Advisory Group.

Corrugated iron was one of the most commonly used building materials of the 20th century. Yet few buildings survive in Sydney as examples of this significant material. Seen as a second-rate or temporary material, corrugated iron was often judged not worthy of retention. Large buildings using corrugated iron are even more rare, making Pier 8/9 a unique survivor.

Corrugated iron was invented and patented in Britain in 1829. It appeared in Australia just a few years later. At first the colonists used it to build verandahs to protect their English style cottages from the sun, but it was soon used for whole buildings.

Valued for its lightweight, cheap, quick construction, corrugated iron was perfect for industrial applications. Wharves have a high incidence of damage due to the number of shipping movements around them, and corrugated iron was a good solution as sheets could be repaired or changed within the day. In fact, the Maritime Services Board had a work gang solely dedicated to fixing shed doors and walls on the wharves.

Pier 8/9 was constructed in 1912 and it is the only corrugated iron pier shed at Walsh Bay. This forms part of its special significance. Originally sheds on all the piers were to be clad with corrugated iron, but shortages due to World War I meant that timber was used on other piers.

The sheds for pier 8/9 were constructed from hardwood storey posts and framing with steel strongbacks to provide more support to the upper floors. They were clad with corrugated iron (in actual fact, corrugated "steel" which replaced iron in the early 20th century).

The wharf buildings had to withstand high stress loadings and bumps from ships - some as large as the Queen Mary during WWII. Millions of tonnes of wool were stored within and moved about the wharves. Corrugated iron proved to be a very good building material to cope with these demands - as were the weatherboards used on the other piers - because it could be easily repaired and replaced.

Pier 8/9 has been adapted for commercial offices by developers, Multiplex, as part of the redevelopment of the Walsh Bay wharves. Heritage architects for the project were Tropman & Tropman Architects.

O.H.M. Consultants were engaged to write a specification and guidelines for the repair of the corrugated iron. Issues that we looked at included the length of sheets, fixing, materials, the size of corrugations (known as pitch), assessments for re-use or disposal and repair methods. Parramatta Tank Works carried out all the repair work to the corrugated iron.

One of our first tasks was to analyse the paintwork used on the pier. The paint survey provided us with the evidence that the corrugated iron walls were mostly original and had withstood 80 years in a hostile sea environment.

The walls were in an excellent condition with probably less then 5% overall so badly damaged that full sheet replacement was required. The roof had been replaced with corrugated asbestos sheet many years before.

As part of the re-use of the building, the work had to comply with modern building requirements. Fire upgrading was required and any lead-based paint had to be removed. Modern comforts meant that the building needed to retain an airtight container for air conditioning. The corrugated iron was therefore removed to place barrier panels behind, and then reinstated.

Many of the repairs subsequently undertaken were to nail holes created by this removal rather than corrosion.

The corrugated iron on the lower levels is still all original. However, the sheeting on the upper levels was replaced with Zincalume. Unlike corrugated iron, Zincalume cannot be lead soldered so repairs such as those carried out on the original material will be impossible in the future.

The work carried out to the original corrugated iron at Pier 8/9 was of an excellent standard. However, too often buildings like this are not valued simply because of their construction material. We risk losing an important part of our built heritage if these corrugated iron structures are demolished without any consideration of what other significance they might have.