Conserving Earth Mortared Monuments in a Damp Climate and Unpredictable Climate

The use of earth mortar and living plants has proved a successful approach to conserving ruined earth mortared masonry in damp and unpredictable climates. On the case study site, conditions include severe exposure to wind-driven rain, ~4m annual precipitation, aggressive vegetation and damage by grazing animals. The monument was unstable due to mortar erosion and legibility was poor. Extensive consolidation with earth mortar was undertaken, with wallheads locally protected from rainwater ingress with a layer of living grass. Exposed earth mortar joints were painted with a clay slip impregnated with grass seeds, designed to grow into a protective layer where conditions were sufficiently damp. In areas too dry for the seeds to grow, the clay would not require this protection and weathered to an exposed aggregate finish. There was an aesthetic intent to make the monuments subtly legible as ruined earth mortared masonry structures clearly distinct in the historic landscape, while mimicking the protective aspects of natural colonization by plants. The use of living plants as conservation materials was designed to act as a buffering layer, preventing climatic decay of the earth mortar, while avoiding damage from roots. The natural colonization of ruined structures by plants is part of their landscape, ecological and aesthetic character, which has been demonstrated to impede decay by mitigating thermal and rainfall extremes. This self-regulating, reversible protective technique has advantages in the context of predicted climate change. The paper presents a way forward for the bio-climatic use of living plants in the benign conservation of earthen structures.

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