|Sina Safinia||Middle East College, Knowledge Oasis Muscat, Rusayl, Post Code 124, Sultanate of Oman|
|Amirhossein Mirsiaghi||Giotas S.A. Wood Industry, No.2, West Zaianderoud, Shiraz St., Molasadra Ave., Tehran, Iran|
building industry in developed countries has seen major growth during the past
century, but Iran, as a developing country, has not yet experienced similar
development. In developed countries, various prefabricated materials which
accelerate the speed of construction are used in the industry. One such
prefabricated material is drywall, which is used globally for the finishing
construction of interior walls and ceilings. Although generally available,
drywall has failed to gain popularity in the Iranian building industry. The
objective of this study is to identify the factors that cause this unpopularity.
Seven potential influencing factors, cost, culture, overall quality,
availability of installation teams, quality of finished surfaces, high skill
requirements and the nature of clients, were identified through a review of the
literature and interviews with consultants and contractors involved in the
Iranian building industry. These factors were included in a questionnaire in
order to analyze their significance and to rate their effect in the industry.
The responses to the questionnaires from 30 construction companies were
statistically analyzed. The results of the data analysis indicate that four
factors are statistically significant in influencing the unpopularity of
drywall: culture, clients, availability of installation teams, and high skill
requirements. The factors were ranked according to their importance.
Building Materials; Construction Industry; Drywall; Iran
The building industry in developed countries has experienced major development during the past century. However, as a developing country, Iran has yet to undergo a similar situation. Its construction techniques are mainly traditional, with any changes limited to structural analysis methods, and to the construction of foundations and reinforced concrete/steel structures. In essence, enhanced analysis techniques are used, although virtually the same conventional construction practices are employed. While the construction of the structural elements of buildings has improved, some other building elements, such as internal walls, are still constructed using traditional materials and methods. One of the main disadvantages of this is the relatively low quality of these materials, which affects the lifespan of the whole building. The average life of a building in developed countries is estimated to be around 80-100 years (Cooke, 2007), whereas it is thought to only be in the region of 20 to 30 years in Iran. An estimated 20% of materials are wasted when using these traditional materials and methods, while this figure is approximately 5% in developed countries (Moetamedi, 2014).
Developments in prefabricated materials manufactured outside building sites contribute greatly to improvements in the building industry, one of these being the accelerated speed of construction (Zhao & Riffat, 2007). Iran urgently needs high quality affordable residential units to replace the worn out urban buildings that are not resistant to earthquakes. There was a sharp rise in the population during 1980s, and this generation is now mature and in need of housing. This will lead to the demand for housing in the coming years to continually increase. A prolonged construction process would make the construction industry fall behind schedule, mainly due to the traditional materials and techniques still used today (Financial Tribune, 2015; Econews, 2016) According to the deputy minister for roads and urban development, Hamed Mazaherian, housing demand is predicted to grow by 5% in the current Iranian year (Khajehpour, 2016). Furthermore, due to the fact that Iran is in an earthquake zone, the practice of employing high quality materials with a low specific weight but high strength is of the utmost importance. The imbalance between the supply and demand of these materials has led to monopolization of the market by a handful of companies which, through the use of poor quality, mainly traditional, materials, has had a negative impact on the Iranian building industry. In addition, the total weight of buildings increases when using traditional materials and techniques. Consequently, as the structure of the building does not achieve an acceptable level of flexibility, the risk and magnitude of damage following an earthquake will increase considerably (Elnashai & Di Sarno, 2015).
The lack of standardization and the poor quality of materials also have an adverse effect on the insurance business. Insurance companies find it difficult to make accurate risk assessments and are often unwilling to insure buildings due to this unpredictability (Alami, 2015). Utilization of standardized, prefabricated, high quality materials and systems such as drywall would maximize efficiency and improve the quality of construction.
1.1. Overview of Drywall Systems
Drywall is a man-made building material and a method of constructing interior walls and ceilings using panels made of gypsum plaster pressed between two thick sheets of paper and then kiln dried. The panels are sometimes called gypsum board, sheetrock or plasterboard (in the USA, UK, Ireland and Australia) (Merriam-Webster, 2015). Nowadays, drywall is commonly used in many types of building construction, such as commercial and residential developments, hospitals, schools, exhibition halls, hotels and restaurants. A large number of manufacturers and contracting companies work in this field around the world. Various types of panels with different sizes and thicknesses are produced. The standard panel size is 1200×2400 mm2, with the thickness varying between 6.5 mm and 20 mm. The standard drywall thickness is 75mm, with a total weight of about 25 kg per square meter. An experienced installation team can typically build 60 square meters of wall per day using this material (Anvari, 2014).
1.2. Scope of the Research
Drywall, in comparison to traditional methods, is not only economical, but also provides significant time savings in installation. However, lack of familiarity with this system in Iran means the benefits have been disregarded by the industry, which still prefers traditional methods. Materials of choice are usually bricks and blocks produced in many different shapes, sizes and colors. These methods, in comparison with drywall, are time consuming and involve a high percentage of waste material; nevertheless, they are commonly used by builders/contractors and stipulated by architects/designers in their designs. This has consequently been the cause of significant delays and extra costs. As mentioned above, the increase in demand for housing requires more efficient building methods, so therefore it is necessary to ascertain what obstacles have prevented the application of this system in Iran. To address this, the study aims to explore the obstacles to the utilization of drywall in the Iranian building industry and to identify the reasons behind its limited application.
1.3. Comparison between Drywall and Traditional Materials
In order to establish the obstacles to using drywall, in this section a comparison will be made between traditional methods, clay bricks and block walls, in terms of cost, weight, speed of construction, thickness, quality of finished surface, availability of expert bricklayers and execution of work.
Figure 1a shows a comparison between the total cost of drywall, clay bricks and clay blocks. Although drywall has the highest cost, it has significant economic benefits, as discussed below. Figure 1b illustrates the total weight of each system. Drywall is the lightest (25 kg/m2); through its use a reduction of 36 percent of the total weight of the building is achieved (Karami, 2015). The main impact of this reduction is to provide a lighter structure than that of steel/reinforced concrete structure. Since the cost of a steel/reinforced concrete structure is about 25 percent of the total construction costs in Iran, this means a significant saving for the builders/clients (Anvari, 2014).
For example, in a five-storey building, of which the total area is approximately 995 square meters, it is possible to reduce the total weight of the steel structure from 45.15 tons to 43.5 tons by using drywall instead of clay brick walls (Azadpoor, 2013). This reduction in weight affects the design radically, hence another benefit of using drywall is the considerable reduction in the amount of concrete, along with the reinforcements in the foundation, particularly in high rise buildings (Emami, 2015).
Figure 1 Comparison between drywall and traditional materials: (a) total cost of each system in IRR (Anvari, 2014); (b) total weight of each system (Karami, 2015)
Unlike structural components, most of the non-structural ones, including architectural, mechanical, electrical and plumbing elements, are vulnerable to relatively low earthquake activity. They contribute significantly to economic losses in buildings subjected to seismic loading (Lee et al., 2006). According to Hirakawa and Kanda (1997), non-structural components represented 40% of the cost of damage to 210 reinforced concrete (RC) buildings affected by the the 1995 Hyogo-ken Nanbu earthquake in Japan, while the cost for structural components was also 40%. Consequently, it is widely agreed that mitigation of non-structural damage will dramatically improve the risk of structures from economic loss. The same is true for the Iranian construction industry, as Iran is in a region prone to earthquakes. Due to its relatively lower weight, utilizing drywall would minimize the risk of damage to structures and also other non-structural components, as mentioned above. In general, a significant degree of protection/damage limitation can be achieved in terms of economic loss due to earthquakes. Furthermore, drywall offers protection to victims who would otherwise perish under the weight of walls built with traditional materials (Karami, 2015).
Figure 2a illustrates that an experienced team, including two expert installers, can construct 60 square meters of drywall in a day, which is 3.75 times faster than using clay bricks and 1.81 times faster than with blocks. Furthermore, in traditional methods, two plastering stages must be implemented before painting, while drywall is ready to be painted on immediately after installation. As a result, a substantial amount of time can be saved in the construction process by applying this system. In addition, during the construction phase of brick/block walls, materials such as cement, sand and clay are left on the floors of the building, which prolongs the process and adds complications. In comparison, the installation of the studs, runners and pallets of No.40 gypsum board panels is less time consuming and complicated (Emami, 2015).
Using drywall in construction is an efficient method of standardizing quality, as the more traditional methods rely mainly on the skills and experience of the bricklayers/laborers, who often lack formal training (Shams, 2014). Figure 2b illustrates the finished thickness of each system. Less interior space is wasted by applying drywall with a thickness of 75 mm.
Figure 2 Comparison between drywall and traditional materials: (a) Speed of construction (Emami, 2015); (b) Thickness of each system (Shams, 2014)
The quality of the finished surface, the floor slab, is important for the drywall installation procedure. Runners need to be installed on a smooth surface. In many countries, when the concrete for the floor slab is poured it is finished off by a power floater. A smooth surface is achieved by this technique; however, in Iran more traditional methods such as manual instrument application are used, meaning a completely smooth surface is hard to create. Unlike drywall, the quality of the floor surface does not have any impact on building walls with brick or clay blocks (Shams, 2014).
Drywall systems should be installed by expert installation teams who are trained and skilled. However, one problem is the shortage of such workers in Iran. On the other hand, there are many skilled bricklayers who can use both bricks and blocks. Furthermore, there is no need for special techniques when constructing traditional walls, so the construction process is less complicated (Shams, 2014). The factors discussed in this section are used in the following one to develop a comprehensive research methodology to thoroughly investigate the barriers that are preventing the application of the drywall system in Iran.
Despite the recent success of drywall in western countries, the system remains unpopular among Iranian construction companies. Seven factors were identified as the main reasons for this problem through a thorough literature review and interviews with companies involved in the construction industry in Iran. These factors were cost, culture, overall quality, availability of installation teams, quality of the finished surface, high skill requirements and clients. The study was based on quantitative and qualitative data collection through interviews and questionnaires. Three factors, namely cost, overall quality and quality of the finished surface proved to be less significant, while the other four were statistically significant. These four factors could act as guides or action points for the government and companies to promote and market the drywall system in Iran
The authors would like to thank the interviewees and respondents for their cooperation in completing this research.
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