THE SUSTAINABILITY OF MASONRY IN CONSTRUCTION TODAY

Masonry is one of the oldest building materials used by man and has been around for thousands of years and is still the most widely used building material. The rich heritage of historic masonry buildings in Canada, Europe, Asia and other parts of the world bears testimony to the sustainability of masonry as a building material. This article looks at how a number of attributes of masonry contribute to sustainable design and construction.

DURABILITY

Masonry units are durable and contribute to building assemblies that remain useful in the material cycle for long periods of time. The use of masonry units, if properly detailed, will minimize the risk and environmental costs of premature failure of building components. Most deterioration occurs to exterior wall components, therefore good building envelope design is essential. 

Besides the durability of the materials used for construction, the actual assemblage of the wall system is fundamental in ensuring the durability of the building. An important aspect of the wall system is the presence of a drainage cavity or rainscreen wall system. The rainscreen wall system anticipates that water will get into the wall, either as permeating through the building materials, or by leakage through deficiencies in windows and other penetrations. The wall system is designed to direct this moisture back to the exterior.  This drainage cavity is an important aspect of any wall system and is now a building code requirement for buildings in the high rainfall area.One of the best reasons for using masonry is its durability and potential for reuse and salvage. Most masonry units can be reused when carefully dismantled. In fact, there is a significant market in Canada for reclaimed clay brick. However, the durability of the masonry units should be checked before reuse. Clay brick manufactured prior to 1950 was often fired in bee hive kilns. Brick on the outer edges of the stack were underfired and were lighter in color. These bricks did not have the durability of facing brick and were used on the inner wythe of a multi-wythe brick wall. During demolition, it is important that these bricks are kept separate from the facing brick.Another aspect to consider when using reclaimed clay brick is the absorption characteristics of the bedding face, which may have been compromised by cement filling the voids. This can affect the potential bond between the mortar and the masonry unit. The initial rate of absorption (IRA) should also be checked before reuse to ensure a proper bond.Because of the durability of masonry and masonry structures, masonry buildings are often ideal candidates for building reuse. Masonry also compares favourably with Life Cycle Analysis (LCA) that includes materials, construction and energy consumption.Masonry is also resistant to other forms of degradation such as fire, mould and termites.Masonry is inherently fire resistant. Interior masonry fire partitions help stop the spread of fire. These aspects reduce the environmental impact of fires. Passive fire protection reduces the costs of buildings.Masonry units are mould resistant and can be used in most environments where people work and live.

STRUCTURE / FINISH COMBINATION

Masonry can provide both the structure and the interior or exterior finish combination which reduce environmental and building costs. Both brick and block walls and columns have high structural load capacity. Most masonry structures are loaded to a fraction of their capacity. Furthermore, the face of masonry is visually attractive and does not need any coatings or finishes, whether installed in an exterior or interior application. LEED offers a credit where low VOC paints and sealers are used, but masonry does not need either, so VOCs are eliminated completely.Masonry walls require very little maintenance, eliminating the need for regular upkeep and repairs and the associated cost and environmental impact.