Durability

Durability is a critical characteristic for all materials and assemblies when sustainably conserving and constructing buildings. The more durable the material, the longer it will last and the less often it will need to be replaced or repaired. When materials in assemblies require less replacement, the lifespan of the overall assembly is increased.

Materials in assemblies are dynamically related to each other. As such, all assembly materials should possess similar durability characteristics to minimize unnecessary loss when less durable materials reach the end of their life. When less durable materials are integrated into an assembly, they should be easily accessible in order to permit replacement while minimizing impact on adjacent sound materials.

It is important that durable materials are maintained appropriately to maximize their effective life; durable does not mean “no maintenance”. For instance, cut stone is a very durable material that, if maintained, can last for centuries in certain environmental conditions. However, the mortar joints must be repointed on a periodic basis using a compatible mortar that acts sacrificially to the stone. Historic window types installed and repaired with window putty provide another example of maintenance within durable assemblies. As the putty ages, it hardens, eventually requiring replacement at the same time the wood and/or steel frames require repainting. Replacing putty and repainting frames extends the life of the overall window assembly.