In March 2023, the Winter Gardens were fully re-opened to the public following a complex two-year project to seismically upgrade and undertake major repairs and improvements to the glasshouses and wider site. The repairs and strengthening works were complex and required a number of changes to the structures, which have been carried out with the utmost care and attention to detail to ensure that the heritage values of the place have been protected and enhanced. This icon site has been conserved for the future. This has been accomplished on time and within the original estimates on behalf of Auckland Council.
The Mission building and ancillary toilet building underwent considerable structural, architectural and services upgrading. Structural upgrading achieved not less than 67% NBS and included: new concrete ground beams set into the existing floor, steel structure built into masonry walls, roof construction bolted to the top of masonry gable walls, reinforced concrete core to chimney and plywood diaphragm fixed over existing ceiling.
Perhaps the most intriguing measure adopted was tying the twin-skin masonry walls together by injecting a super fluid lime-based product into the void of loose rubble, this effectively satisfying the objective to have a stronger single wall, rather than two weaker walls.
Remedial work to architectural elements included: replacement cedar shingle roofing including copper rainwater goods, repairing existing or reinstatement of missing original ornate features, window and door restoration and clearing away of non-original partitions on the mezzanine level. Services upgrading included the removal and replacement of pre-existing electrical and plumbing.