Bristile Roofing sourced unglazed terracotta tiles from Spanish manufacturer La Escandella Ceramica for installation on the roof of the Pantanassa Monastery Church near Sydney.
The Pantanassa Monastery Church is a Greek Orthodox church that sits high on a rugged bluff an hour north of Sydney, accessible only by a track carved through the bush.
Aware of the church’s plan to eventually cover the interior walls and ceilings with icons and religious images painted directly onto the surfaces, Demetrios Stavropoulos of Design Delta Architects decided that the substrate on which the painting would be done needed to have a durable construction to last hundreds of years.
Resistance to moisture penetration and earth movement (critical because of the site’s proximity to Newcastle) were the two key requirements for the structure.
A monolithic concrete shell designed by structural engineers, Luke Tsougranis and Associates was constructed incorporating walls, vaulted ceilings and arches supported on conventional formwork whereas the three-dimensional curves for domes and half domes required laser-cut Styrofoam formers coated with fibreglass to resist the weight and impact of wet concrete.
The concrete walling is shielded by a cavity and an outer leaf of brickwork from Austral Bricks’ Bowral dry-pressed range. But the low roof pitch and the varying dome pitch prevented the tiles from eliminating water entry.
Connell Wagner engineered a membrane solution consisting of an acrylic coating over the entire concrete roof shell, which was then covered with a second, thinner concrete layer to protect the membrane from penetration during construction and provide a platform for the tiles and other fixings.
As the head laying contractor, Bristile Roofing installed the unglazed La Escandella terracotta tiles in two sizes with the smaller size for the dome. The single half-cylinder profile of the roof tiles provided the tolerance to allow the tiles to fan and be laid more tightly than conventional roof tiles.
For aesthetic reasons, every row in the dome needed to have the same number of tiles, which was achieved by progressively cutting their length and width to maintain the frequency and allowing them to follow the dome’s unique profile.
Alternate tiles were inverted to cup with their neighbours. All tiles were wet-bedded with dabs of mortar, and the upper gaps mortar-filled to reduce penetration by wind-driven rain.
Water entering the roof flows under the tile assembly and overflows the building edge into the stormwater system. Visible flashing was avoided for aesthetic reasons with concealed dish drains intercepting the water where the roofs abutted the brick walls.
La Escandella terracotta roof tiles have again been chosen for the next stage of the project involving the construction of the monks’ quarters, kitchen, refectory and library.