Promoted as the first concrete building in the Waikato, the store was erected alongside the Waikato River, close to the mill and other structures. It was designed as a two-storeyed granary, rectangular in plan, with a series of small windows lighting its upper floor. Its concrete walls were chosen for their fire- and rat-proof qualities, incorporating imported Portland cement. They also contained strands of ungalvanised barbed wire, leading its architect - T.H. White - to claim it as the earliest reinforced concrete building in the Southern Hemisphere. The subsequent history of the store is less well-known, but it was evidently used for storing finished products rather than grain after the mill was taken over by the Waikato Steam Navigation and Coal Mining Company in 1883. With the regional flour business in decline, it was then employed in association with a local revival of flax production, being part of the Walsh Brothers' operations from 1889 to around 1915. The building has since been adapted by the Ngaruawahia Regatta Association to house canoes for their annual regatta. The Association was formed in 1896 to preserve Maori customs, at a time when it was feared that they would disappear.
The building is of considerable historical value for its connections with the development of agriculture and flour production in the Waikato, as well as the late nineteenth-century revival of flax. It is significant as the only visible remnant of the largest colonial flour mill in the region, demonstrating changes in ownership, technology and the scale of production after the third New Zealand War. It is particularly important as it is the oldest known concrete building in the region, and a pioneering example of rudimentary reinforced concrete construction in New Zealand. It is the earliest known concrete building erected by T.H. White who trained in Britain and France, the main centres of innovation in nineteenth-century concrete technology. The building has strong connections with the development of Ngaruawahia, reflecting the town's commercial importance in the nineteenth century. It is highly significant for its historical and cultural links with the Waikato River, including the activities of the Ngaruawahia Regatta Association.



