The building elements contain all elements that are part of the construction of a building primarily. Examples are walls, doors, beams, and they are tangible and exist physically. The following are some of the building elements that are used in contemporary commercial and domestic buildings: Foundation, Ground floor, Upper floors, Roof structure, Windows, and External Walls. The report is about the evolution of a building structure that is used in contemporary commercial and domestic buildings. The building element that is discussed in this report is the external walls(American Institute of Architects, 2016, p. 126). The construction of external walls defines the walls adjacent to the outside section of the building. This research paper is about the evolution of the external walls, environmental impacts, and alternative materials that can be used in the construction of external walls.
Evolution of External walls
In the period of early brick work, there were a number of improvements in making bricks during the 1700s. Better techniques of moulding blended clays, and more even firing resulted in greater uniformity in the size and shape of the brick. In late 1600, the popular colours of the bricks were purples and reds which gave way to softer colour brown in the 1730s. By 1800, the production of stocks of yellow London provided the colour of the brick not much different from natural stone. The machines of moulding and improved mixing together with best techniques for firing enabled the production of brick to attain new heights(Architects, 2009, p. 158).
The bricks were obtainable in different types of shapes, colour, and strength that would not have been imagined previously in a hundred years. The better techniques of quarrying enabled extraction of deeper clays which produce dense and strong bricks utilized in works of civil engineering such as bridges and canals(Architects, 2007, p. 269).
Brick Bonding was the next stage after early brick work. By the end of 19th century, a majority of the houses possess walls of a single brick thickness. Houses of storeys had walls that are thicker normally reducing in thickness at every level of the upper floor. The majority of the houses were built in a bond of Flemish even though few walls or walls were hidden by render were mostly laid in a bond of garden-wall(Beadle, 2013, p. 147).
The stonework was the next stage after brick bonding. The stone was normally used in regions where it occurred naturally or for prestige. In upland areas, a stone was the obvious choice for building because it was available readily. There are three categories of stones which include sedimentary, igneous, and metamorphic. Sedimentary group comprise of sand stones and limestone which accounts for most of the stones used in the construction. Rubble walling is found in numerous styles at its cheapest.(California, 2013, p. 159).
In a majority of cases, a stone wall has to be thicker than a brick-wall. The stone-work which is dressed or cut finely is normally referred to as dimension stone or free stone; meaning that it can be worked with a saw and a chisel in any direction. It is free from laminations and has fine grains and is pronounced bedding plains. During the 18th century, the whole city was rebuilt and build with stones. It was economical to build the whole wall in free stone and a backing material or brick work(Christensen, 2017, p. 219).In a majority of houses, only the elevation of the front side will be built in free stone, the back and sides being built with bricks or rubble. The bonding stones were used in bonding the two halves of the walls together. These structures were made with mortar of lime that slowly became hardened. Hydraulic lime was unknown and was not common since they were expensive. Also, they always set quickly leading to more wastage on the site(Christensen, 2017, p. 193).
The mortar was the next stage after stonework. The lime mortar was available until the 1930s. Chalk or limestone was burnt with coal to form quick lime that was mixed with water and with fine aggregates to form the motor. Alternative choice was to utilize lime which has silica naturally. During the 1930s and 1940s, motor cement replaced lime. Lime was normally added to the mix to improve its quality, durability, and working(Doug Oughton, 2010, p. 239).
Pointing followed the mortar as the next stage in construction. In the periods of early 1900s, the joints were normally finished flush or recessed slightly. The joints were normally eight millimetres or less where better quality bricks were used. This, together with the use of dust brick in a motor meant that the motor had little effect on the appearance of the building. Tuck-pointing was reserved for the best work quality. It can be categorized into two parts which are bedding-motor which contain an aggregate to match with the brick's colour or a thin ribbon and stonework of line pointing to end the joint(Engineer, 2012, p. 217). The diagram below shows the 19th-century pointing:
Cavity Walls followed the pointing as the next stage in construction. Many houses were built with cavity walls in the 19th century. The cavity walls were very cheap to build than the counterparts which are made of solid walls. Also, they offer improved thermal insulation and good protection from harsh weather. The brickwork of external leaf was built in facing brick and the interior leaf in common. The little cavity walls of early had an exterior leaf which has a thickness of one brick and in some form of the building. The diagram below shows an example of early cavity walls(Stein, 2009, p. 148).
The 1930s to 1960s external wall followed the cavity walls in construction. During this time, the walls of cavity changed significantly. The motors became cement based instead of lime based since the faster motor setting made the construction to be faster. For the inner leaf of cavity walls, the common material was block-work. The blocks were made with the industrial waste or aggregate stone. During this time, several houses were built in construction style which was not traditional styles by the use of panels or frames of pre cast; in some occasion, insitu panels(Smith, 2016, p. 193).
The 1970s to 1980s external walls was the next stage of evolution of the external walls. During the 1970s, there was a slow improvement of standard insulation, the optimum value of U of 1.70 was introduced to find out the ability of the wall to heat transmission. To achieve this level was very easy; a brick exterior leaf, cavity of 50 millimetres, plus block interior leaf that is dense completed with 13-millimeter plaster of light-weight. In 1980, the optimum value of U decreased to one; this needed block-work of light weight in inner leaf. From this period up to date, the blocks of light weight have been made from concrete which is aerated. They were made from lime, cement, sand, and powder of aluminium. After these constituents are combined with boiling water, the powder of aluminium mixes with lime to form the pockets of hydrogens which are minute(Siegenthaler, 2012, p. 197).
Modern Cavity walls formed the next stage of evolution of the external walls. During the 1990s, the optimum value of U reduced further to 0.45 which usually needed a thick inner leaf that is lightweight or insulation cavity. There are three choices, which need lightweight or block which is aerated in the interior leaf. They include the cavity with a dry lining that is insulated, insulation board that partially fills the cavity, and insulation batts which fill the cavity. There is a possibility of building walls which are solid but not using the bricks, the accepted level of insulation can be gotten only by aerated concrete. The modern cavity wall has a U value six or five times better than the counterparts of the 1920s(Portman, 2014, p. 279). Also, the cavity widths have increased beyond 50 millimetres eighty years ago.
Wall Tires followed modern cavity walls in construction. Wall tires are the common stainless steel. There are numerous patterns which include the washer for holding insulation board in position against the inner leaf.
Modern Mortars followed the wall tires as the next stage of evolution of the external walls. Modern mortars are made from sand and cement. Lime which is hydrated is introduced frequently into the mixture to give out the full of plastic and to make it much workable. Lime improves the ability of the motor to deal with moisture and thermal movement. Recently, it has become common to use the pre-mixed mortar. These are distributed to the site in containers which are sealed and ready for use.
They normally have retarder and remain usable for 36 hours to 48 hours of more(Lars Engstrom, 2010, p. 169). At the termination of this time, they improve on strength as normal mortars. The joint phase may be completed in many ways, the most common are joints that are tooled where the pressing of the mortar occurs to the brick-work and give the best protection of the weather since the tooling compresses and smoothers the joint.
Environmental Impacts of External Walls
The environmental impacts of the components making up the external walls can be categorized in terms of its design, selection, manufacture, maintenance, disposal, reuse, installation, and use.
Use and Selection
The components making the external walls have numerous impacts on the environment when they are used in the constructions as explained in this section. The solution of clay brick may be better since the components used in making it by the manufacturers are all environmental friendly; the components include the clay soil and water. The structure of a concrete wall could have poor performance on the environment than the bricks of clay in terms of wood emission to the water, and also emission from the materials used during the construction(Stein, 2009, p. 124).
The solution of a concrete block may have good performance on the environment than the solution of the clay brick in terms of climatic change and the consumption of energy and water. The solution of auto-craved aerated concrete could have a good performance of the environment than the clay bricks or concrete blocks that are normal in acidification of the atmosphere, production of inert waste, and emission to the air but bad in the water consumption.
The disposal of the components of the clay bricks has less environmental effects when disposed of compared to the normal concrete block since the components making the clay brick can be disposed of without any effect on the environment.The structure of a concrete wall could have poor performance on the environment than the bricks of clay in terms of wood emission to the water, and also emission from the materials used during the construction due to the production of cement.(Robert Judson Clark, 2016, p. 214).
The solution of auto-craved aerated concrete could have a good performance of the environment when disposed of than the clay bricks or concrete blocks that are normal in acidification of the atmosphere, production of inert waste, and emission to the air but bad in the water consumption. The timber wall of lightweight may have good performance to the environment when disposed of than the concrete blocks, clay, structural concrete or walls of the steel frame in terms of the consumption of energy, global warming, and emissions to soil and air. The cellular concrete can be used in covering rubble without polluting the soil.(Austroads Limited, 2013, p. 187).
Some of the components of the external walls may be reused with less waste being released into the atmosphere while other components cannot be reused at all. The solution of clay brick can be recycled after being in a construction for a long duration hence making it environmentally friendly. The clay bricks may often be reclaimed for re-use during the demolition of the structure. The re-use of the structures made of concrete is a method of utilizing the rabble. The re-use has a benefit that makes it more attractive and friendly to the environment.
The auto-craved aerated concrete may be reused though the application may cause a problem due to a high amount of sulphate that is leachable and are not friendly to the environment. The re-use of the wooden boxes of wall frames can add details which are unique to the walls decoration and are environmentally friendly. The re-use of timber wall is environmentally friendly since the timbers are chipped into wood chips and are used in power plants or power homes. The re-use of timber wall is a more sustainable. The re-use of cellular concrete is economical since it utilizes reusable materials and also have characteristics which prevent the increase in deterioration(California, 2013, p. 236).
During the manufacture of the components used in making the external wall, there are some environmental impacts faced in the processes. In the manufacture of clay brick, the environmental impacts that will be observed include the interference of the soil structure, emission of smoke to the atmosphere leading to the destruction of the ozone layer, and deforestation when woods from trees are used to make the clay bricks. This solution could have a lower performance of the environment than a normal concrete block in this environmental category. The manufacture of blocks and bricks in either concrete or clay utilized energy, however, the investment of embodied energy is repaid by longevity of the material.
During the manufacture of clay brick, the emission of huge elements that are toxic from the bricks causes the environmental and health hazard. In the manufacture of the concrete wall, the process of making cement results to the high level of carbon dioxide emission which is not friendly to the environment. During the manufacture of frame wall, the production of carbon monoxide, phenol, and formaldehyde which irritate the environment causing acidification of the air. The manufacture of timber wall has a high environmental impact, the combustion of fossil fuel leads to the environmental degradation and global warming(Littlefield, 2010, p. 269).
A properly constructed and designed brick work need little maintenance since it will not require another coating or painting in managing the moisture.The maintenance of clay brick and the concrete wall should be done through proper measures since any release to the atmosphere may lead to global warming, change in climate, acidification, inert waste production, emission to the atmosphere, and consumption of energy(Galinsky, 2010, p. 169).
During the installation of autoclaved aerated concrete as it rains, it can crack after the installation and cause the environmental degradation. The installation of cellular concrete reduces the amount of excavation, minimize site disruption, reducing carbon, saving time, and money hence fewer effects on the environment. Local production reduces distances for shipping building materials, minimize the requirements for fuel for handling and transportation hence reducing carbon dioxide emission. The installation of cellular concrete, concrete block, timber wall, and frame wall should be carried out properly since improper misuse may lead to a change in climate, acidification, emission to the atmosphere, and consumption of energy(Engineer, 2012, p. 247).
The selection of the components to use in building the external wall is based on the effects of the components will have on the environment. The cellular concrete is a light weight concrete that is good for environmentally friendly building. It is made by combining air, lime, water, cement, and sand. The aluminium powder reacts with lime to release hydrogen gas to create the air bubbles. After hardening, the material’s density becomes fair and contain numerous bubbles of air and produces thermal features. The cellular concrete and the wooden structures should be selected during the construction of the external walls(Mike Riley, 2013, p. 247).
Alternative materials to use in External Walls
The alternative building materials that can be used in constructing an environmentally friendly external walls include wooden structure, cellular concrete, insulating load bearing clay brick, and euromac structure. The reason why they are considered as alternative choices for constructing external walls are explained below:
Wooden structure: Wood occupies a place in green building approach. There are numerous different possible terms of wooden structure. The walls can be made using beams of solid wood, walls will laminated timber, and glued, and wooden structures of the frame which is good for the environment of urban as they look identical in conventional construction.(California, 2013, p. 168). Wood naturally protects itself since it contains polyphenol which has the effects of disinfectants. It is also a good hygrometric and thermal regulator.
Insulating load bearing clay brick: The bricks are becoming important in the approach of green building. It does not need insulating cladding on either outside or inside sides. It has admirable performance since it is durable and resistance to regulation. The brick of insulating clay gives technology that makes deployment simple(American Institute of Architects, 2016, p. 198). It emits nontoxic gases in the event of combustion. The brick is involved in the absorption of heat from the system of heating and redistribute it through the process of radiation and hence reduce the consumption of energy.
Euromac structure: This system of construction consists of two cladding insulation wall made of a high density of expanded polystyrene joined by two spacer metals that are reinforced in their lateral part by flat bands of metals. The concrete is then poured in the cladding up to 3.5 meters. This system of the wall is protected from seismic and have a variable width and properties of thermal insulation which provides insulation and effect from fire depending on the wall's thickness.(Siegenthaler, 2012, p. 136).
Cellular concrete: This is a light weight concrete that is good for a sustainable building. It is made by combining air, lime, sand, cement, and water. The powder of aluminium reacts with lime to release hydrogen gas to produce the bubbles of air. After hardening, the material's density becomes fair and contain numerous bubbles of air and produces thermal features. The cellular concrete can be recycled and can be used in covering rubble without polluting the soil.(Christensen, 2017, p. 278).
The building elements that are used in contemporary domestic and commercial buildings include foundation, ground floor, upper floors, roof structure, and windows. This report specifies on the evolution of external wall which is an important building element. The evolution of the external wall followed the sequence starting from early brickwork, brick bonding, stonework, mortar, pointing, cavity walls, the 1930s to 1960s, 1970s to 1980s, modern cavity walls, wall ties, and modern mortars. It is necessary to consider the future development potential of the external wall that has been discussed below:
Future development potential of the external wall
The following are some of the technologies which will be used in future for the development of the external wall:
Technologies for remodeling the external walls: This would be the case for curtain walls for high constructions or part of walls in the flats or residential blocks. This procedure will make it possible to reach large sections of buildings with a crane of the building which could be beneficial when a large part of the building is remodeled(Mike Riley, 2013, p. 138).
Technologies for applying exterior layers: External insulation is the preferred method for adding insulation to the building which is exciting. This method minimizes the loss of space since it is possible to work which the building is in use and also avoid moisture problem and thermal bridge.
Technology for inserting material in cavities in the walls which are existing: Walls with cavity can improve their temperature property when the materials are put inside these cavities. This will be the future development of the external wall.
Technology for applying interior insulation: The new part of the construction will be made to the carrying system of the external existing wall, floor dividers, and internal bearing wall(Christensen, 2017, p. 159).
The environmental effects of the external wall include climate change, global warming, acidification, eutrophication, and atmospheric emissions. The alternative materials that can be used in the construction of the external wall include euromac structure, wooden structure, insulating load bearing clay brick, and cellular concrete.
Abdelmonem, D. M. G., 2015. The Architecture of Home in Cairo: Socio-Spatial Practice of the Hawari's Everyday Life. India: Ashgate Publishing, Ltd.
Alan Blanc, M. M. R. P., 2013. Architecture and Construction in Steel. Paris: Taylor & Francis.
American Institute of Architects, K. E. H., 2016. Architectural Graphic Standards. Michigan: John Wiley & Sons.
Architects, R. I. o. B., 2007. RIBA Journal, Volume 67. China: RIBA Services Limited.
Architects, R. I. o. B., 2009. Journal of the Royal Institute of British Architects, Volume 67. Berlin: The Institute.
Austroads Limited, E. C., 2013. Building and Construction Procurement Guide: Principles and Options. Paris: Austroads Limited.
Beadle, L., 2013. Tall Buildings and Urban Habitat. London: CRC Press.
California, T. U. o., 2013. Architect and Engineer, Volumes 140-143. New York: The University of California.
Christensen, A. C., 2017. Separation Scenes: Domestic Drama in Early Modern England. Brazil: U of Nebraska Press.
Doug Oughton, S. H., 2010. Faber & Kell's Heating and Air Conditioning of Buildings. California: Routledge.
Doug Oughton, S. H. R. M. B., 2014. Faber & Kell's Heating & Air-conditioning of Buildings. Berlin: Routledge.
Engineer, W. A. a., 2012. Western Architect and Engineer, Volumes 142-143. London: McGraw-Hill Company of California.
Galinsky, K., 2010. Classical and Modern Interactions: Postmodern Architecture, Multiculturalism, Decline, and Other Issues. California: University of Texas Press.
Lars Engstrom, S. r. f. b. (., 2010. Summary of Energy in the built environment: the way forward to the 1990s. Sweden: Swedish Council for Building Research.
Littlefield, D., 2010. Metric Handbook. London: Routledge.
Mike Riley, A. C., 2004. Construction Technology 2: Industrial and Commercial Building. Michigan: Palgrave Macmillan.
Mike Riley, A. C., 2013. Construction Technology 1: House Construction, Volume 1. Paris: Palgrave Macmillan.
Portman, J., 2014. Building Services Design Management. Berlin: Wiley.
Ragette, F., 2013. Traditional Domestic Architecture of the Arab Region. California: Edition Axel Menges.
Robert Judson Clark, A. P. A. B. D. I. o. A. M. M. o. A. (. Y. N., 2016. Design in America: The Cranbrook Vision. California: Metropolitan Museum of Art.
Siegenthaler, J., 2012. Modern Hydronic Heating: For Residential and Light Commercial Buildings. London: Cengage Learning.
Smith, A., 2016. The differential use of constructed sacred space in Southern Britain, from the Late Iron Age to the 4th century AD. London: Archaeopress.
Stein, B., 2009. Building Technology: Mechanical and Electrical Systems. Michigan: John Wiley & Sons.
Stein, B., 2009. Building Technology: Mechanical and Electrical Systems. Michigan: John Wiley & Sons.