- The term "materials" refers to all the physical substances that are assembled to create the interior and exterior of a building.
- Today most buildings are constructed from a multitude of materials, each with very specific functional demands and complex assembly requirements
- An exterior wall assembly contains materials that keep the rain and wind out, thermally insulate the inhabitants from exterior temperatures, structurally support the building and the associated enclosure system, and provide desired interior and exterior finishes. In addition, windows, doors, vents, and other apertures connect to the interior and exterior of the building. The list could go on, but this example should serve to illustrate the complexity and importance of the material selection process in building design.
These decisions should be based on a number of carefully considered issues -
- Physical Properties
- Particular materials carry specific connotations within cultures and regions. Terms such as natural or artificial, eternal or ephemeral, austere or opulent, describe a few such associations. We often refer to the enduring qualities of stone, or the ephemeral nature of glass or paper.
- In some cases, the material associated with a desired symbolic expression is not available or too costly, and another material is substituted to replicate that material and achieve the desired effect.
- There are three primary areas that must be evaluated in selecting appropriate materials and assemblies.
- Material Compatibility with Climatic, Cultural, and Aesthetic Conditions
- Climate is one of the most important factors to consider in material and assembly selection. Materials also must be compatible with specific regional and local cultural and aesthetic conditions.
- Applicability of Material to Occupancy and Size of Building, Including Durability, Structural, and Fire Protection Requirements
- Material choices are often legally limited by the building type and size, in order to protect public health, safety, and welfare. For instance, a detached single-family house has far fewer limitations than a high-rise office building or a federal courthouse, from which hundreds of inhabitants must be evacuated in case of emergency. In general, buildings with large occupancy numbers (especially assembly occupancy such as theaters, lecture halls, and restaurants) and greater enclosed square footage require more fire-resistant construction and more complex fire protection systems. Another concern is the added wear and tear on a densely inhabited and intensely used building, such as a public school or hospital, where material durability is a major concern
- Environmental Impact of Obtaining Raw Materials, Processing and Fabricating Building Materials, Transportation Impact, and Recycling Issues
A number of physical properties must be taken into account in the material selection process. While certain properties are inherent to the material and unchangeable, other qualities can be determined in the fabrication or finishing process. The following outline lists only primary considerations, since each material possesses a unique combination of properties.
- Strength: Material strength quantifies resistance to compression, tension, and other types of loading on a given material. For instance, masonry performs most effectively as a load-bearing or compressive material, while steel is a more suitable choice for greater spanning and tensile requirements.
- Mass and Thickness: After an initial material selection is made, the dimensional thickness of each material must be based on requirements for durability, strength, and aesthetic considerations.
- Physical and Visual Density: Often a particular tactile density is desired, ranging from heaviness to lightness in degrees of opacity, translucency, or transparency.
- Texture: Many materials may be finished to different textures, either during off-site production or while finishing materials on-site. Smooth to rough, soft to hard, and a range of surface finishes—matte, satin, polished, and so on
- Selection of a building color palette must consider the surrounding context, as well exterior and interior light qualities under which the colors will be viewed.
- The cool diffused light of Seattle will render colors quite differently than the hot clear light of Phoenix.
- Colors may be light absorptive or light reflective, warm or cool, while the palette may be monochromatic or polychromatic
- Temperature: The tactile qualities of architecture are of utmost importance, especially those surfaces that building inhabitants touch on a regular basis, such as door hardware, work surfaces, and floor materials. Metal surfaces quickly register temperature change, while stone more slowly absorbs ambient temperatures and retains temperature much longer. Thus, material thermal conductivity is an important consideration in the comfort of occupants.
- Pattern: Material patterning must be designed at two scales: the individual elements themselves, such as bricks or glass panes, and the composition of these elements into larger assemblies. For example, at the individual element scale the inherent patterning of wood grain or stone marbling must be considered. The creation of larger patterns occurs when the material is assembled into building facades
- The methods of material fabrication and assembly are a complex aspect of the construction process. Technique includes the fabrication process, the detailing of how materials and systems are joined and erected, and the craft employed to execute the work.
- Fabrication: Fabrication refers to how a material was created, processed, and assembled. Fabrication techniques range from handcrafted to mass produced to prefabricated. Materials carry traces of their making and assembly that can be used to create surface modulation and richness.
- Detail: Construction details determine how individual material elements or systems are joined. Common methods of joinery include various types of mechanical fastening (nails, bolts, rivets...), welding, adhering, and so on. Construction details should relate to the overall architectural intentions of a building.
- Craft: The quality of design and construction workmanship is crucial to the success and longevity of a project. The employment of well-trained and experienced trades people is the best way to assure a high level of building craft