Walls and Window Teatments

WALLS AND WINDOW TREATMENTS 3(1+2)

Lesson 2 : Materials For External Wall

Factors Influencing The Choice Of Materials

The decisions relating to material selection process in building design should be based on a number of carefully considered issues as described below, including symbolism, appropriateness, physical properties and technique, and product performance and longevity of appeal.

Symbolism of style

Particular materials carry specific connotations within cultures and regions. Terms such as natural or artificial, everlasting or temporary, sober or lavish, describe a few such associations. Stone is often associated with natural, everlasting and sober whereas glass is artificial and temporary. 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

Appropriateness to pupose

There are three primary areas that must be evaluated in selecting appropriate materials and assemblies.

• Material Compatibility with Climatic, Cultural, and Aesthetic Conditions
• Applicability of Material to Occupancy and Size of Building, Including Durability, Structural, and Fire Protection Requirements
• Environmental Impact of Obtaining Raw Materials, Processing and Fabricating Building Materials, Transportation Impact, and Recycling Issues

Physical Properties of Materials

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 are determined in the fabrication or finishing process. The following outline lists only primary considerations, since each material possesses a unique combination of properties.

1. 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.

2. 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.

3. Physical and Visual Density: Often a particular tactile density is desired, ranging from heaviness to lightness in degrees of opacity, translucency, or transparency.

4. 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—are possible.

5. Color: 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.

6. 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.

7. Pattern: Material patterning must be viewed 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.

8. Technique: 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.

9. 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.

10. Detailing: The quality of design and construction workmanship is crucial to the success and longevity of a project. Construction details should relate to the overall architectural intentions of a building. Attention to detail is evident in a well-resolved and finely executed building, such as the elegant assemblage of wood and concrete Craft

11. Weathering: The passing of time has an immense impact on the appearance and life span of building materials. Thus, future weathering must be carefully considered during material selection, building detailing, and construction.