Transition from wood to iron in French theatre structures: A new construction system

In the second half of the 18th century, France was a significant centre for the use of wrought iron in civil architecture. Due to the promise of fireproof constructions, theatres were among the first to incorporate the newmaterial, since ironwas believed to be more resistant than timber. Many ideas and architectural proposals emerged, aiming to improve theatre design and construct robust, fire-proof structures. In particular, an innovative construction system combining wrought iron trusses and fillings of hollow pots was proposed in the 1780s. This article focuses on the transition to iron in Parisian theatre roofs and on the application of this new construction system. The contribution of theatre structures in the application of iron and the development of "fire-proof" trusses is highlighted through archival plans and preserved examples.