Protecting the Stone Artworks of the Seventeenth Century Portico of the House of Pieter Paul Rubens in Antwerp (Belgium) from Wind Driven Rain

The forthcoming restoration campaign of the former house of the Flemish Baroque painter Pieter Paul Rubens (1577–1640) in Antwerp includes the design and construction of a new glass canopy. It is to replace the actual non-transparent roof structure, which was erected in the 1990s to protect the portico, separating the inner court yard of the house from the gardens, and especially its sculptural artworks from further material loss. The design parameters of the new glass canopy were evaluated based on the distribution probability of the rain on the portico as a function of rain intensity and wind velocity, while the rain distribution was determined based on the raindrop trajectories combining the vertical raindrop velocity and the horizontal drag from the wind. A minimum wind velocity of 40 km/h is required before rain can reach the feet of the sculptured artworks during intense rain showers. Statistical analysis of the hourly wind velocity and rain shower duration and intensity reveals a return period of approximately 4.2 years when the portico is protected by a glass canopy with identical dimensions of the actual provisory roof structure. Although the influence of intermittent wind gusts and squalls, which will more frequently drag along rainwater to the critical areas, and increase the amount of rainwater attaining the artworks during storms, could so far not be studied more in detail. The above risks are however considered acceptable to prevent future damage accumulation.