The temple ruins of Hagar Qim and Mnajdra on the island of Malta are now protected by two PTFE-glass (woven fiberglass coated with a PTFE resin) membrane roof structures.
The previously unprotected soft limestone of the temples had been deteriorating from exposure to the environment when excavations began.
Meeting the UNESCO standards for conservation and protection posed unique challenges for the design and structural team of formTL and Walter Hunziker Architekten AG. In addition to providing effective protection from the weather, the design of the canopies needed to be removable while leaving no visible impact on the site and to accommodate the astronomical alignment of the temple buildings.
Since the topography was difficult to document, the design and geometry of the structures were continually adjusted in parallel to the development of a 3D survey. The temple complex could not be disturbed so the usual machinery and scaffolding couldn't be used. Professional climbers were brought in to assemble the cable and membrane structures over the site.
The elegant canopies are cable nets with membrane panels supported by arching steel trusses. The cable net is biaxial, allowing for arched forms with no additional stabilizing cables. Filtering UV rays by 85 to 90 percent, the PTFE-coated glass fabric still allows for natural lighting.
The two temple complexes were recognized as UNESCO World Heritage Sites in 1992 and the canopy project was completed in 2011.
This post was originally published on Smartplanet.com