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Explain Exterior Walls
Explain exterior walls speaks to what are exterior walls and types of exterior walls.
It is also known as the exterior wall enclosure and the building envelope is the part of a building that must protect the interior spaces against invasion by water, wind, sunlight heat and cold, humidity and the other forces of nature.
The design is an intricate and complicated process that merges art, science and craft to solve a long list of demanding problems. The exterior wall also exposes a building concern in that those parts of a building that are exposed to view are also those that are exposed to wear and weathering.
The outermost layer of the exterior wall is the most visible part of a building, one to which the designer devotes a great deal of time to achieve the desired visual effect. It is also the part of the building that is most subject to attack by natural forces that can diminish its appearance.
The primary functions of the exterior wall is to separate the indoor environment from the outdoors in such a way that indoor environmental conditions can be maintained at levels suitable for the building’s intended use. This requires consideration of a number of separate and divers functional requirements.
Keep Water
Out to Explain Exterior Walls
The exterior wall must prevent the entry of rain, snow and ice into a building. This requirement is complicated by the fact that water on the face of a building is often driven by wind at high velocities and high air pressures not just in a down ward direction but in every direction even upward.
Water problems are especially acute on tall buildings, which present a large profile to the wind at altitudes where wind velocities are much higher than at ground level. Enormous amounts of water must be drained from the windward face of a tall building during a heavy rainstorm and the water, pushed by wind, tends to accumulate in crevices and against projecting mullions, where it will readily penetrate the smallest crack or opening and enter the building.
Prevent
Air Leaks to Explain Exterior Walls
The exterior wall of a building must prevent the unintended passage of air between indoors and outdoors. This is necessary to regulate air flow within the building. Smaller air leaks are harmful because they waste conditioned cooled or heated air, carry water vapour through the wall, allow water vapour to condense inside the wall and allow noise to penetrate the building from outside.
Building code requirements for air tightness of building enclosures are growing more stringent. Sealants, gaskets, weatherstrips and air barrier membranes of various types are all used to prevent air leakage through the exterior wall.
Light
Control to Explain Exterior Walls
The exterior wall of a building must control the passage of light, especially sunlight. Sunlight is heat that may be welcome or unwelcome. Sunlight is visible light, useful for illumination but bothersome if it causes glare within a building. It includes destructive ultraviolet wavelengths that must be kept off human skin and away from interior materials that will fade or deteriorate.
Windows should be placed and proportioned with these considerations in mind. Exterior wall systems sometimes include external shading devices to keep light and solar heat away from the windows. The glass in windows is often selected to control light and heat. Interior shades and blinds and curtains may also be used for further control.
Heat
Radiation Control to Explain Exterior Walls
Beyond its role in regulating the flow of radiant heat from the sun, the exterior wall of a building should also present interior surfaces at temperatures that will not cause radiant discomfort. A very cold interior surface will make people feel chilly when thry are near the wall even if air in the building is warmed to a comfortable level.
A hot interior surface or direct sunlight in summer can cause overheating of the body despite the coolness of the interior air. External sun shading devices, adequate thermal insulation and thermal breaks and appropriate selection of glass are potential strategies in controlling heat radiation.
Heat Conduction
The exterior wall of a building must resist the conduction of heat into and out of the building. This requires not merely satisfactory overall resistance of the wall to the passage of heat but also avoidance of thermal bridges, wall components such as metal framing members that are highly conducive of heat and therefore likely to cause localized condensation on interior surfaces.
Thermal insulation, appropriate glazing and thermal breaks are used to control heat conduction through the exterior wall. Building codes specify minimum values of thermal resistance of wall components as a way of limiting the conduction of heat and also as a way of controlling the condensation of moisture on cold interior surfaces.
Sound Control
The exterior wall serves to isolate the inside of a building from noises outside and vice versa. Noise isolation is best achieved by walls that are airtight, massive and resilient. The required degree of noise isolation varies from one building to another, depending on the noise levels and noise tolerances of the inside and outside environments.
The exterior wall for a hospital near a major airport requires a high level of noise isolation. The exterior wall for a commercial office in a suburban office park need not to perform to as high a standard as a hospital.
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