Why are roofs and drainage systems important in the conservation of old buildings?

In the field of art conservation and restoration, roofs and drainage systems are critical because moisture is considered one of the most serious adversaries to the structural integrity and aesthetic preservation of old buildings.12

The Role of Roofs and Drainage

The roof serves as a building's first line of defense against the elements. Its primary function is to remain impervious and to collect water, directing it safely away from the structure. When roofing materials fail—often due to the decay of fixings or the age of materials like lead—water can infiltrate the building, leading to significant damage.1

Drainage systems, including gutters and rainwater-collecting systems, are equally vital. They prevent the accumulation of water that would otherwise penetrate porous surfaces or find its way through structural defects.1

Impact of Moisture on Conservation

Neglecting these systems allows dampness to infiltrate, which accelerates decay in several ways:
* Structural Weakening: Moisture weakens walling, rots timber, and can lead to the growth of destructive fungi, such as dry rot, and wood-boring insects.1
* Damage to Finishes: For buildings containing wall paintings, leaking roofs and clogged drainpipes cause issues like blanching, drip staining, and the formation of damaging salt deposits.2
* Accelerated Deterioration: Dampness compounds other problems, such as the erosion of lime-based materials caused by atmospheric pollutants.12

Conscientious maintenance of roofs and drainage is the most effective preventative treatment in building conservation, as it addresses the root cause of moisture-related decay before it necessitates complex or intrusive repairs.12