The widespread introduction of Portland cement-based mortars and synthetic polymer coatings during late 20th-century renovations represents a catastrophic disruption to the historic built environment. Pre-1948 solid masonry walls are dynamic, vapor-permeable systems designed to absorb and evaporate moisture across their entire surface area—a mechanism colloquially known as “breathing.” The application of a modern, rigid Portland [...]

The architectural integrity of historic French properties depends fundamentally on the material properties of traditional stone masonry and breathable mortars. Unlike modern construction, which relies on rigid Portland cement and impermeable vapor barriers, pre-1948 structures (le bâti ancien) operate as dynamic, moisture-transmitting systems. Preserving these historic assets requires a strict adherence to traditional material sciences. [...]