During the renovation process of Hofmeyrsaal, a historic building in Montagu, we prioritized the breathability of the system. By stripping the clay walls of their old plasters and performing necessary repairs, we laid the foundation for enhancing the building’s breathability. To achieve this, our team utilised airPLAST lime plasters for all the walls, ensuring an optimal breathability. In addition, we applied airCOAT, a lime-based paint, to maintain the system’s breathability over time. Crucially, we learned that cement should not be used, even for patching, in a heritage breathable system, as it can impede breathability and potentially lead to moisture-related issues. By exclusively employing lime-based materials, we have successfully preserved and improved the breathability of Hofmeyrsaal, a true heritage gem.