St Pauls Church - Preserving the heritage character

We were commissioned, alongside Salmond Reed Architects to complete a seismic assessment and retrofit design for the St Paul’s Church on Symonds Street in Auckland.

St Paul’s Church is Auckland’s oldest church and the current building is a great example of Gothic Revival architecture. It consists of two portions – the original church, and a rear extension.

The original church was constructed of unreinforced stone and brick masonry in 1894 and the rear extension was built of RC frames with clay brick infill panels in 1936.

St Paul’s had been defined as a Category 1 heritage building by Heritage New Zealand, meaning that the works needing to be carried out by EQSTRUC must maintain its heritage design and value. Previously, other consultants had proposed a more traditional retrofit method that were rejected by the client due to the implications the retrofit would have on the heritage features of the church.

This meant that we had to ensure our retrofit concept must maintain the heritage design and value of the Church. This proved to be problematic given that the building consists of stone, masonry, timber and concrete.

By utilising point cloud technology, we were able to identify areas of strength and weakness, ultimately resulting in a cost-effective solution by using the existing material properties to their advantage.

For the original Un-Reinforced Masonry (URM) church, the plan was to retrofit the stone arch spandrels with near-surface mounted fibre reinforced polymer strips, which are intended to improve both the shear and axial capacities of the spandrels and minimize the visual impacts on the heritage features of the church.

The lower portion of the limestone piers in the nave area were confined using a fibre reinforced polymer wrap. During a major earthquake, devastating energy will be dissipated by allowing piers to rock in a stable fashion as controlled by altering the height of the fibre reinforced polymer wrap, and consequently, forces to be resisted by the structure will be lowered substantially.

Our team are proud of the result and had a lot of fun working on this project given that it’s such a prestigious building in the central city of Auckland.