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Assessment of the length of scantlings across timber markets in the north-central region of Nigeria
Scientific African 6 (2019) e00139
Contents lists available at ScienceDirect
Scientific African journal homepage: www.elsevier.com/locate/sciaf
Assessment of the length of scantlings across timber markets in the north-central region of Nigeria Ahmed Mohammed Kamaruddeen a,∗, Bashir Hussain Yahaya b a b
Quantity Surveying Programme, University College of Technology Sarawak, No.1 Jalan Universiti, 96000 Sibu, Sarawak, Malaysia Department of Quantity Surveying, Federal Polytechnic Nasarawa, Nasarawa State, Nigeria
a r t i c l e
i n f o
Article history: Received 1 January 2019 Revised 15 June 2019 Accepted 26 August 2019
Editor: Dr. B. Gyampoh Keywords: Timber scantling Timber length Standard length Timber market
a b s t r a c t The renovation of heritage and historical timber buildings will require the removal of decayed or deteriorated timbers and the replacement with new-strong timbers. The accuracy in estimating such timber renovation work largely depends on the knowledge of the estimator about the exact length of the timber scantling that will be supplied to the site. This paper aims to determine whether the timber scantlings sold across the timber markets in the north-central states of Nigeria are up to the standard length of 3.66 m. This research used a descriptive research design and quantitative research approach, to randomly select two shops from 3 timber markets located in the north-central region of Nigeria for data collection. 50 mm × 50 mm, 50 mm × 75 mm, 50 mm × 100 mm, and 50 mm × 150 mm timber scantlings were randomly selected and physically measured using a tape rule. Thirty-seven (37) samples of 50 mm × 50 mm, 50 mm × 75 mm, 50 mm × 100 mm, and 50 mm × 150 mm timbers were picked from each of the three markets. A descriptive analysis was used to determine the mean length of each size across the three surveyed timber markets. This study found that the average length of the timber sold across the markets was less than 3.66 m. The implication is that it becomes imperative for estimators to make inquiries concerning the average length of timbers scantling sold in the market before calculating the required quantities of any timber-related projects. © 2019 The Author(s). Published by Elsevier B.V. on behalf of African Institute of Mathematical Sciences / Next Einstein Initiative. This is an open access article under the CC BY license. (http://creativecommons.org/licenses/by/4.0/)
Introduction This paper investigates the length of timber scantlings sold across the timber markets in the north-central region of Nigeria. The aim is to determine whether the timber sold in the markets are up to 3.66 m long (required length). This study focuses on timber because it is one of the significant works in the restoration of heritage buildings and, in particular, the historical timber buildings [21]. Naturally, historical buildings will, at one point in time, face any of the common aging factors such as leakage, dampness, and loss of strength. If further deterioration is to be avoided in such buildings, conservation through a renovation process will be required to improve the building’s lifespan [1]. Renovation of a heritage building usually requires a repair to maintain the initial usage or to serve additional purposes [4]. Such repair, be it a renovation ∗
Corresponding author. E-mail address: [email protected] (A.M. Kamaruddeen).
https://doi.org/10.1016/j.sciaf.2019.e00139 2468-2276/© 2019 The Author(s). Published by Elsevier B.V. on behalf of African Institute of Mathematical Sciences / Next Einstein Initiative. This is an open access article under the CC BY license. (http://creativecommons.org/licenses/by/4.0/)
2
A.M. Kamaruddeen and B.H. Yahaya / Scientific African 6 (2019) e00139
or upgrading work, will generally require the removal and replacement of old building materials with new building materials, such as timber, ceiling, wall or floor finishes [8]. Hence additional cost is incurred. Depending on the scope of work, a contractor may be required to do the repair or renovation work under competitive or non-competitive bidding. After the successful tender, it becomes the responsibility of the contractor’s estimator to calculate the actual number of each needed material for the implementation of the project [8]. The process of calculating the exact amount is generally known as the material schedule. The calculation requires the knowledge of the standard dimensions for all the construction materials such as the standard length of a timber scantling. There will be a shortfall if the length of timber sold in the market is less than 3.66 m long (example, 3.45 m) and the estimator uses the standard length of 3.66 m for calculating the number of timber scantling required for a project (a process known as material schedule). The small difference between the standard length and the actual length in the market will cause a shortfall in the accuracy of the estimate (underestimate). This shortfall will generally result in requesting additional materials; by implication, additional cost has to be incurred either by the owner of the project in the case of an in-house or labor-only contract. But if it is a traditional contract, the profit of the contractor might reduce due to the purchase of additional timber caused by the shortfall. From the quantity surveyor’s point of view, the differences may appear to be small per each timber scantling, but the cumulative effect will eventually lead to the purchase of additional materials. As the cost or estimate is crucial in any renovation work, a better understanding of the sizes of building materials such as the length of timber sold in the market is also necessary [15]. Thus, contractors and consulting quantity surveyors should be informed about the average length of timber scantling to be used in preparing their material schedule for all timber-related works [16]. Hence, this research seeks to determine the average length of timber scantling sold across selected building materials markets in the north-central region of Nigeria. Literature review Timber Timber is a major building, furniture and decorating material. Its usage has a long history due to its unique characteristics and can be obtained locally in many countries. Timbers are used in both rural and urban dwellings such as shops, houses, and offices as doors and windows, roofs, floors, internal walls, porches and verandas, ceilings, and staircases [12]. Historical buildings and royal palaces, which are constructed entirely by using timber, can still be found in countries like Malaysia and Singapore [21]. Though the modern roofing construction materials are mainly aluminum and steel, which has led to the reduction in the usage of timber as roofing materials, timber is still useful in the restoration of historical and heritage buildings. Cost estimation of timber According to Zolkafli et al. [21], there is an inaccurate estimation of predetermined specification, duration, and cost of building or cost of constructing conservation projects. This shortfall has been associated with the uniqueness of every conservation project and the lack of precedent cases in conducting conservation-related research. According to Woon and Mui [20], there is difficulty in the preparation of estimates for the restoration of heritage buildings due to lack of accurate assessment in the information and the knowledge of the intricacies of renovation works among quantity surveyors. It is, therefore, not surprising to have very few specialists that are familiar with the maintenance of projects [18]. Since the cost estimation is crucial to the contractor tendering for any renovation works [15], a better understanding of the sizes of building materials such as the length of timber sold in the market is necessary. Thus contractors and consulting quantity surveyors should be informed about the average length of materials to be used in preparing their material schedule for timber works [16]. This knowledge can reduce the inaccuracy of cost estimation that could significantly affect the contractors’ businesses, mainly when the projects constitute a large number of timber works [2]. Overestimating and underestimating have their consequences: clients do not accept overestimate and contractors incur losses due to inaccuracy in the cost estimate [3]. An accurate cost estimate that is closer to the client’s estimate thus increases the chance of being awarded the project [14]. Restoration In the same line of thought as Harun [10], this paper defines the restoration of a building as the process of removing all depleted materials or components and replacing them with new-functional materials to recover its original forms, details, and settings. In the context of heritage, renovation works aim at preserving the history, culture, or legacy which the building symbolizes or represents [9]. Among the building materials that mostly require replacement during the renovation of roofs in heritage buildings is timber. Some timbers are known to be vulnerable to dampness, insects, fungi, or termites attack [13]. Thus, the restoration will be required from time-to-time to address such problems and to sustain the lifespan of the heritage or historical buildings. According to Zolkafli et al. [21], restoration work in historical timber buildings requires the replacement of the damaged part of the building including the timber itself as a measure to prevent further deterioration, to maintain the original function, aesthetics, and strength of the building.
A.M. Kamaruddeen and B.H. Yahaya / Scientific African 6 (2019) e00139
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Table 1 Mean lengths of four sizes of timber from three different timber markets. S/No
Sizes of timber
Statistical parameter
Standard size length (m)
Deidei market (A) (m)
Nyanya market (B) (m)
1
50 × 50 mm 50 × 75 mm 50 × 100 mm 50 × 150 mm 50 × 50mm 50 × 75 mm 50 × 100 mm 50 × 150 mm
Mean
3.66 3.66 3.66 3.66 0.00 0.00 0.00 0.00
3.42 3.42 3.39 3.42 0.15 0.16 0.13 0.20
3.49 3.51 3.42 3.42 0.08 0.07 0.14 0.09
2
The standard deviation of the mean
Nasarawa market (C) (m) 3.43 3.48 3.45 3.43 0.13 0.08 0.07 0.06
Conservation Conservation is a concept which encompasses various dimensions such as preservation, refurbishment, rehabilitation, maintenance, restoration, reconstruction, repair, and adaptive reuse [6,7]. It means that the term conservation could be applied to different contexts depending on the actual pathway to preserving a historical or heritage building. Hence, preservation, refurbishment, rehabilitation, maintenance, restoration, reconstruction, repair, or adaptive reuse can be carried out with the sole aim of maintaining a historical or heritage building [17]. Methodology Sampling and sample Timber scantling was the unit of analysis in this study. Data were collected from the shops that permitted the researchers to measure their timbers. However, in choosing the timber scantling to be measured, a simple random sampling technique was used to select each timber scantling from the stack of timbers. The simple random sampling technique was used in this study to enable an equal chance of choosing any timber scantling in the stack and be able to generalize the research findings [19]. Data collection The data for the study were obtained from three timber markets, namely the Deidei building material market and the Nyanya timber market both located in Abuja. The third market is the timber shade in Nasarawa town, Nasarawa State. Abuja and Nasarawa State are both in the north-central region of Nigeria. Thirty-seven (37) timber scantlings of 50 × 50 mm, 50 × 75 mm, 50 × 100 mm, and 50 × 150 mm from each of the three selected markets were measured. The length of each chosen timber scantling was measured using tap rule. The procedure was repeated for all the sizes of the timbers examined in this study (50 × 50 mm, 50 × 75 mm, 50 × 100 mm, and 50 × 150 mm). The readings were recorded as soon as the timbers were measured. A total of two hundred and ninety-six (296) timber scantlings were measured in each timber market. The total number of timber scantling measured across all the three markets was eight hundred and eighty-eight (37 timber scantling × 4 different sizes × 2 timber shops × 3 timber markets). Differences in the species of timbers that were measured were not a significant concern of this study. The reason is that the focus of this study was to measure the length of the scantling irrespective of the timber’s species. Data analysis The different lengths recorded in the markets were analyzed in comparison to a standard length of 3.66 m, which is used in the calculation of the material schedule for timber-related works. The lengths of the timbers’ sizes were analyzed using Microsoft Excel to obtain the mean and standard deviation. The mean scores were then compared with the standard length of timber scantling (3.66 m). Results Table 1 presents the summary of the lengths of the four (4) different sizes of timbers randomly selected and measured. As shown in Table 1, the average timber scantling length across all sizes of timbers in the Deidei market was 3.41 m, in the Nyanya market, it was 3.46 m, and 3.45 m long in Nasarawa market. The range of standard deviation was between 0.06 and 0.2, indicating that there was no much variance among the timber scantling in each of the three timber markets. Fig. 1 presents the average length for each size of timber scantlings. Nyanya market showed the highest mean length in 50 × 50 mm (3.49 m), and 50 × 75 mm (3.51 m). Nasarawa market showed the most top mean length in 50 × 100 mm (3.45 m), and 50 × 150 mm (3.43 m).
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A.M. Kamaruddeen and B.H. Yahaya / Scientific African 6 (2019) e00139
Fig. 1. Mean lengths of four different sizes of timber across three timber markets. Table 2 Analysis of variance among the timber sizes across the three markets. Market (mean)
50 × 50 mm 50 × 75 mm 50 × 100 mm 50 × 150 mm
Deidei market
Nyanaya market
Nasarawa market
3.42 3.42 3.39 3.42
3.49 3.51 3.42 3.42
3.43 3.48 3.45 3.43
F
Sig.
4.185 5.872 2.426 .056
.018 .004 .093 .945
Table 2 presents the significant differences in the timbers’ sizes in the three markets. One-way ANOVA analysis indicated that there were significant differences between 50 × 50 mm (F = 4.185, p < 0.05) and 50 × 75 mm (F = 5.872, p < 0.01). The 50 × 50 mm timber scantlings from the Nyanaya market showed the highest mean length (3.49 m) compared to the Deidei market (3.42 m) and the Nasarawa market (3.43 m). Similarly, the 50 × 75 mm from the Nyanaya market showed the highest mean length (3.51 m) compared to the other markets. The result also indicated no significant difference for timber sizes of 50 × 100 mm, and 50 × 150 mm across the three timber markets. Discussion This research is an extension of Houchen’s work [11] which highlighted the need for consultation with the timber trade before the time of design and specification to avoid any situation that may result in added cost. The result of this study implies that every estimator of timber-related works should find out the exact length of timber sold in the market before using that length in calculating the number of timbers required for a project. The 3.66 m standard length of timber scantling used as a reference and compared with the average length of timber across the markets examined in this study applies to all parts of Nigeria [5]. In other words, 3.66 m is the standard length of timber scantling across the timber markets in Nigeria irrespective of the timber species. The results indicated the length of timers sold across the markets examined in this study is less than 3.66 m. However, there is a significant difference in 50 × 50 mm and 50 × 75 mm across the three markets while there were no significant differences in 50 × 100 mm and 50 × 150 mm timber scantlings across the three markets. The reason for the mixed findings could be due to differences in the extent of production and usage of 50 × 50 mm and 50 × 75 mm compared to 50 × 100 mm and 50 × 150 mm. 50 × 50 mm and 50 × 75 mm timbers are often used more for timber-related work in addition to the roof truss. Another reason for the mixed findings could be due to the few numbers of timber shops from which data were collected. Conclusion This study investigated the average length of four sizes of timbers sold across three timber markets in the north-central region of Nigeria. It explored the average difference between the standard length (3.66) and the length sold across the surveyed timber markets. Results suggest that the lengths of the four sizes (50 × 50 mm, 50 × 75 mm, 50 × 10 mm, and 50 × 150 mm) are similar within the same market but vary across the three markets. Also, it was found that the length of the four sizes of timbers was not up to the required 3.66 m long within and across the three surveyed markets. For improving the efficiency of estimators and the accuracy of timber restoration projects, the average length of timber sold across the selected timber markets in the north-central region of Nigeria was established in this paper. Though the analyses
A.M. Kamaruddeen and B.H. Yahaya / Scientific African 6 (2019) e00139
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used in this paper were less rigorous, the objective of the research was achieved. This paper is not only an essential step towards the identification of accurate estimation of timber-related projects but goes further to create awareness among the estimators and renovation contractors on the need to be knowledgeable about the actual sizes of building materials sold in the markets or supplied to site for the execution of any project. In other words, this work will assist in creating more awareness, especially in the process involved in the estimation of timber-related projects. The reason is that the difference in the required length and the actual length available in the market is useful for the preparation of the materials schedule. Hence, an essential contribution of this paper is on the accuracy of cost estimation and preparation of material schedule for timber-related projects, such as roof restructuring and renovation of historical buildings using timber. A major limitation acknowledged in this study was the relatively small sample size. Not all the timber shop owners permitted a physical measurement of the timbers they sell. Future research should replicate this research across other regions of Nigeria. Such endeavor will enable a comparison of the length of timber scantlings sold across Nigerian timber markets. This study offers specific practical implications to the construction estimating professionals such as the Quantity Surveyors. While the literature confirms that the standard length of timber scantlings is 3.66 m long in Nigeria, estimators should also confirm the average length of timber scantling sold in the timber markets. The findings in this study will guide them on the exact length for calculating the number of timber materials required for any timber-related projects. Government agencies responsible for enforcing building standards should, in addition to the quality of materials, regulate the needed sizes of building materials sold in the various markets. Declaration of Competing Interest The authors certify that there is no conflict of interest associated with this manuscript. Acknowledgments The authors thank all the Higher National Diploma students of Federal Polytechnic Nasarawa that participated in the data collection. References [1] A.G. Ahmad, H.F. Abdul-Rahman, Restoration and refurbishment of old city hall, Georgetown, Penang, Malaysia, in: W. Yaowu (Ed.), Proceedings of the International Conference on Construction and Real Estate Management, 2005. [2] A. Akintoye, Analysis of factors influencing project cost estimating practice, Const. Manag. Econ. 18 (2) (20 0 0) 77–89. [3] A. Akintoye, M. Skitmore, Profitability of UK construction contractors, Const. Manag. Econ. 9 (4) (1991) 311–325. [4] N. Atakul, M.J. Thaheem, A. De Marco, Risk management for sustainable restoration of immovable cultural heritage, part 1: PRM framework, J. Cult. Herit. Manag. Sustain. Dev. 4 (2) (2014) 149–165. [5] J.O. Ayeni, Principles of Tendering and Estimating, second ed., Builder’s Magazine Limited, Lagos, 1997. [6] P.A. Bullen, Adaptive reuse, and sustainability of commercial buildings, Facilities 25 (1/2) (2007) 20–31. [7] N. Dann, S. Wood, Tensions and omissions in maintenance management advice for historic buildings, Struct. Surv. 22 (3) (2004) 138–147. [8] R. Fabbri, L. Gabrielli, A.G. Ruggeri, Interactions between restoration and financial analysis: the case of Cuneo War Wounded House, J. Cult. Herit. Manag. Sustain. Dev. 8 (2) (2018) 145–161. [9] B.M. Feilden, Conservation of Historic Buildings, (3rd Ed), Architecture Press, 2003. [10] S.N. Harun, Historical Building Conservation in Malaysia: Experience and Challenges, University Teknologi, MARA Perak, 2011. [11] C. Houchen, A specifier’s guide to timber, Structural Survey 10 (3) (1992) 248–253. [12] W. Killman, S. Tom, L.T. Hong, Restoring and Reconstructing the Malay Timber House, Forest Research Institute Malaysia, Kuala Lumpur, 1994. [13] J. Kleboe, Timber and the Built Environment Conference, Historic Scotland, Edinburgh, 2004. [14] B.T. Lim, F.Y. Ling, C.W. Ibbs, B. Raphael, G. Ofori, Empirical analysis of the determinants of organizational flexibility in the construction business, J. Constr. Eng. Manag. 137 (3) (2010) 225–237. [15] N.K.F. Mustafa, S. Johar, A.G. Ahmad, S.H. Zulkarnain, M.Y.A. Rahman, A.I. Che-Ani, Conservation and repair works for traditional timber mosque in Malaysia: a review on techniques, World Academy of Science, Eng. Technol. 5 (5) (2011) 663–668. [16] P. Oram, The Repair and Maintenance of Historic Buildings: A Brief Guide for owners, Architects, and Agents, The Northern Ireland Historic Building Council, Belfast, 1994. [17] L.K. Quah, Comparative variability in tender bids for refurbishment and new build work, Construct. Manag. Econ. 10 (3) (1992) 263–269. [18] J. Reyers, J. Mansfield, The assessment of risk in conservation refurbishment projects, Struct. Surv. 19 (5) (2001) 238–244. [19] U. Sekaran, R. Bougie, Research Methods for Business: A Skill-Building Approach, John Wiley & Sons, 2013. [20] W.L. Woon, L.Y. Mui, Elemental cost for building conservation worked in Malaysia, Struct. Surv. 28 (5) (2010) 408–419. [21] U.K. Zolkafli, Z. Yahya, N. Zakaria, F.W. Akashah, A.S. Ali, Restoration of historical timber building: a Malaysian case study, Struct. Surv. 33 (4/5) (2015) 309–321.
Contents lists available at ScienceDirect
Scientific African journal homepage: www.elsevier.com/locate/sciaf
Assessment of the length of scantlings across timber markets in the north-central region of Nigeria Ahmed Mohammed Kamaruddeen a,∗, Bashir Hussain Yahaya b a b
Quantity Surveying Programme, University College of Technology Sarawak, No.1 Jalan Universiti, 96000 Sibu, Sarawak, Malaysia Department of Quantity Surveying, Federal Polytechnic Nasarawa, Nasarawa State, Nigeria
a r t i c l e
i n f o
Article history: Received 1 January 2019 Revised 15 June 2019 Accepted 26 August 2019
Editor: Dr. B. Gyampoh Keywords: Timber scantling Timber length Standard length Timber market
a b s t r a c t The renovation of heritage and historical timber buildings will require the removal of decayed or deteriorated timbers and the replacement with new-strong timbers. The accuracy in estimating such timber renovation work largely depends on the knowledge of the estimator about the exact length of the timber scantling that will be supplied to the site. This paper aims to determine whether the timber scantlings sold across the timber markets in the north-central states of Nigeria are up to the standard length of 3.66 m. This research used a descriptive research design and quantitative research approach, to randomly select two shops from 3 timber markets located in the north-central region of Nigeria for data collection. 50 mm × 50 mm, 50 mm × 75 mm, 50 mm × 100 mm, and 50 mm × 150 mm timber scantlings were randomly selected and physically measured using a tape rule. Thirty-seven (37) samples of 50 mm × 50 mm, 50 mm × 75 mm, 50 mm × 100 mm, and 50 mm × 150 mm timbers were picked from each of the three markets. A descriptive analysis was used to determine the mean length of each size across the three surveyed timber markets. This study found that the average length of the timber sold across the markets was less than 3.66 m. The implication is that it becomes imperative for estimators to make inquiries concerning the average length of timbers scantling sold in the market before calculating the required quantities of any timber-related projects. © 2019 The Author(s). Published by Elsevier B.V. on behalf of African Institute of Mathematical Sciences / Next Einstein Initiative. This is an open access article under the CC BY license. (http://creativecommons.org/licenses/by/4.0/)
Introduction This paper investigates the length of timber scantlings sold across the timber markets in the north-central region of Nigeria. The aim is to determine whether the timber sold in the markets are up to 3.66 m long (required length). This study focuses on timber because it is one of the significant works in the restoration of heritage buildings and, in particular, the historical timber buildings [21]. Naturally, historical buildings will, at one point in time, face any of the common aging factors such as leakage, dampness, and loss of strength. If further deterioration is to be avoided in such buildings, conservation through a renovation process will be required to improve the building’s lifespan [1]. Renovation of a heritage building usually requires a repair to maintain the initial usage or to serve additional purposes [4]. Such repair, be it a renovation ∗
Corresponding author. E-mail address: [email protected] (A.M. Kamaruddeen).
https://doi.org/10.1016/j.sciaf.2019.e00139 2468-2276/© 2019 The Author(s). Published by Elsevier B.V. on behalf of African Institute of Mathematical Sciences / Next Einstein Initiative. This is an open access article under the CC BY license. (http://creativecommons.org/licenses/by/4.0/)
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A.M. Kamaruddeen and B.H. Yahaya / Scientific African 6 (2019) e00139
or upgrading work, will generally require the removal and replacement of old building materials with new building materials, such as timber, ceiling, wall or floor finishes [8]. Hence additional cost is incurred. Depending on the scope of work, a contractor may be required to do the repair or renovation work under competitive or non-competitive bidding. After the successful tender, it becomes the responsibility of the contractor’s estimator to calculate the actual number of each needed material for the implementation of the project [8]. The process of calculating the exact amount is generally known as the material schedule. The calculation requires the knowledge of the standard dimensions for all the construction materials such as the standard length of a timber scantling. There will be a shortfall if the length of timber sold in the market is less than 3.66 m long (example, 3.45 m) and the estimator uses the standard length of 3.66 m for calculating the number of timber scantling required for a project (a process known as material schedule). The small difference between the standard length and the actual length in the market will cause a shortfall in the accuracy of the estimate (underestimate). This shortfall will generally result in requesting additional materials; by implication, additional cost has to be incurred either by the owner of the project in the case of an in-house or labor-only contract. But if it is a traditional contract, the profit of the contractor might reduce due to the purchase of additional timber caused by the shortfall. From the quantity surveyor’s point of view, the differences may appear to be small per each timber scantling, but the cumulative effect will eventually lead to the purchase of additional materials. As the cost or estimate is crucial in any renovation work, a better understanding of the sizes of building materials such as the length of timber sold in the market is also necessary [15]. Thus, contractors and consulting quantity surveyors should be informed about the average length of timber scantling to be used in preparing their material schedule for all timber-related works [16]. Hence, this research seeks to determine the average length of timber scantling sold across selected building materials markets in the north-central region of Nigeria. Literature review Timber Timber is a major building, furniture and decorating material. Its usage has a long history due to its unique characteristics and can be obtained locally in many countries. Timbers are used in both rural and urban dwellings such as shops, houses, and offices as doors and windows, roofs, floors, internal walls, porches and verandas, ceilings, and staircases [12]. Historical buildings and royal palaces, which are constructed entirely by using timber, can still be found in countries like Malaysia and Singapore [21]. Though the modern roofing construction materials are mainly aluminum and steel, which has led to the reduction in the usage of timber as roofing materials, timber is still useful in the restoration of historical and heritage buildings. Cost estimation of timber According to Zolkafli et al. [21], there is an inaccurate estimation of predetermined specification, duration, and cost of building or cost of constructing conservation projects. This shortfall has been associated with the uniqueness of every conservation project and the lack of precedent cases in conducting conservation-related research. According to Woon and Mui [20], there is difficulty in the preparation of estimates for the restoration of heritage buildings due to lack of accurate assessment in the information and the knowledge of the intricacies of renovation works among quantity surveyors. It is, therefore, not surprising to have very few specialists that are familiar with the maintenance of projects [18]. Since the cost estimation is crucial to the contractor tendering for any renovation works [15], a better understanding of the sizes of building materials such as the length of timber sold in the market is necessary. Thus contractors and consulting quantity surveyors should be informed about the average length of materials to be used in preparing their material schedule for timber works [16]. This knowledge can reduce the inaccuracy of cost estimation that could significantly affect the contractors’ businesses, mainly when the projects constitute a large number of timber works [2]. Overestimating and underestimating have their consequences: clients do not accept overestimate and contractors incur losses due to inaccuracy in the cost estimate [3]. An accurate cost estimate that is closer to the client’s estimate thus increases the chance of being awarded the project [14]. Restoration In the same line of thought as Harun [10], this paper defines the restoration of a building as the process of removing all depleted materials or components and replacing them with new-functional materials to recover its original forms, details, and settings. In the context of heritage, renovation works aim at preserving the history, culture, or legacy which the building symbolizes or represents [9]. Among the building materials that mostly require replacement during the renovation of roofs in heritage buildings is timber. Some timbers are known to be vulnerable to dampness, insects, fungi, or termites attack [13]. Thus, the restoration will be required from time-to-time to address such problems and to sustain the lifespan of the heritage or historical buildings. According to Zolkafli et al. [21], restoration work in historical timber buildings requires the replacement of the damaged part of the building including the timber itself as a measure to prevent further deterioration, to maintain the original function, aesthetics, and strength of the building.
A.M. Kamaruddeen and B.H. Yahaya / Scientific African 6 (2019) e00139
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Table 1 Mean lengths of four sizes of timber from three different timber markets. S/No
Sizes of timber
Statistical parameter
Standard size length (m)
Deidei market (A) (m)
Nyanya market (B) (m)
1
50 × 50 mm 50 × 75 mm 50 × 100 mm 50 × 150 mm 50 × 50mm 50 × 75 mm 50 × 100 mm 50 × 150 mm
Mean
3.66 3.66 3.66 3.66 0.00 0.00 0.00 0.00
3.42 3.42 3.39 3.42 0.15 0.16 0.13 0.20
3.49 3.51 3.42 3.42 0.08 0.07 0.14 0.09
2
The standard deviation of the mean
Nasarawa market (C) (m) 3.43 3.48 3.45 3.43 0.13 0.08 0.07 0.06
Conservation Conservation is a concept which encompasses various dimensions such as preservation, refurbishment, rehabilitation, maintenance, restoration, reconstruction, repair, and adaptive reuse [6,7]. It means that the term conservation could be applied to different contexts depending on the actual pathway to preserving a historical or heritage building. Hence, preservation, refurbishment, rehabilitation, maintenance, restoration, reconstruction, repair, or adaptive reuse can be carried out with the sole aim of maintaining a historical or heritage building [17]. Methodology Sampling and sample Timber scantling was the unit of analysis in this study. Data were collected from the shops that permitted the researchers to measure their timbers. However, in choosing the timber scantling to be measured, a simple random sampling technique was used to select each timber scantling from the stack of timbers. The simple random sampling technique was used in this study to enable an equal chance of choosing any timber scantling in the stack and be able to generalize the research findings [19]. Data collection The data for the study were obtained from three timber markets, namely the Deidei building material market and the Nyanya timber market both located in Abuja. The third market is the timber shade in Nasarawa town, Nasarawa State. Abuja and Nasarawa State are both in the north-central region of Nigeria. Thirty-seven (37) timber scantlings of 50 × 50 mm, 50 × 75 mm, 50 × 100 mm, and 50 × 150 mm from each of the three selected markets were measured. The length of each chosen timber scantling was measured using tap rule. The procedure was repeated for all the sizes of the timbers examined in this study (50 × 50 mm, 50 × 75 mm, 50 × 100 mm, and 50 × 150 mm). The readings were recorded as soon as the timbers were measured. A total of two hundred and ninety-six (296) timber scantlings were measured in each timber market. The total number of timber scantling measured across all the three markets was eight hundred and eighty-eight (37 timber scantling × 4 different sizes × 2 timber shops × 3 timber markets). Differences in the species of timbers that were measured were not a significant concern of this study. The reason is that the focus of this study was to measure the length of the scantling irrespective of the timber’s species. Data analysis The different lengths recorded in the markets were analyzed in comparison to a standard length of 3.66 m, which is used in the calculation of the material schedule for timber-related works. The lengths of the timbers’ sizes were analyzed using Microsoft Excel to obtain the mean and standard deviation. The mean scores were then compared with the standard length of timber scantling (3.66 m). Results Table 1 presents the summary of the lengths of the four (4) different sizes of timbers randomly selected and measured. As shown in Table 1, the average timber scantling length across all sizes of timbers in the Deidei market was 3.41 m, in the Nyanya market, it was 3.46 m, and 3.45 m long in Nasarawa market. The range of standard deviation was between 0.06 and 0.2, indicating that there was no much variance among the timber scantling in each of the three timber markets. Fig. 1 presents the average length for each size of timber scantlings. Nyanya market showed the highest mean length in 50 × 50 mm (3.49 m), and 50 × 75 mm (3.51 m). Nasarawa market showed the most top mean length in 50 × 100 mm (3.45 m), and 50 × 150 mm (3.43 m).
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Fig. 1. Mean lengths of four different sizes of timber across three timber markets. Table 2 Analysis of variance among the timber sizes across the three markets. Market (mean)
50 × 50 mm 50 × 75 mm 50 × 100 mm 50 × 150 mm
Deidei market
Nyanaya market
Nasarawa market
3.42 3.42 3.39 3.42
3.49 3.51 3.42 3.42
3.43 3.48 3.45 3.43
F
Sig.
4.185 5.872 2.426 .056
.018 .004 .093 .945
Table 2 presents the significant differences in the timbers’ sizes in the three markets. One-way ANOVA analysis indicated that there were significant differences between 50 × 50 mm (F = 4.185, p < 0.05) and 50 × 75 mm (F = 5.872, p < 0.01). The 50 × 50 mm timber scantlings from the Nyanaya market showed the highest mean length (3.49 m) compared to the Deidei market (3.42 m) and the Nasarawa market (3.43 m). Similarly, the 50 × 75 mm from the Nyanaya market showed the highest mean length (3.51 m) compared to the other markets. The result also indicated no significant difference for timber sizes of 50 × 100 mm, and 50 × 150 mm across the three timber markets. Discussion This research is an extension of Houchen’s work [11] which highlighted the need for consultation with the timber trade before the time of design and specification to avoid any situation that may result in added cost. The result of this study implies that every estimator of timber-related works should find out the exact length of timber sold in the market before using that length in calculating the number of timbers required for a project. The 3.66 m standard length of timber scantling used as a reference and compared with the average length of timber across the markets examined in this study applies to all parts of Nigeria [5]. In other words, 3.66 m is the standard length of timber scantling across the timber markets in Nigeria irrespective of the timber species. The results indicated the length of timers sold across the markets examined in this study is less than 3.66 m. However, there is a significant difference in 50 × 50 mm and 50 × 75 mm across the three markets while there were no significant differences in 50 × 100 mm and 50 × 150 mm timber scantlings across the three markets. The reason for the mixed findings could be due to differences in the extent of production and usage of 50 × 50 mm and 50 × 75 mm compared to 50 × 100 mm and 50 × 150 mm. 50 × 50 mm and 50 × 75 mm timbers are often used more for timber-related work in addition to the roof truss. Another reason for the mixed findings could be due to the few numbers of timber shops from which data were collected. Conclusion This study investigated the average length of four sizes of timbers sold across three timber markets in the north-central region of Nigeria. It explored the average difference between the standard length (3.66) and the length sold across the surveyed timber markets. Results suggest that the lengths of the four sizes (50 × 50 mm, 50 × 75 mm, 50 × 10 mm, and 50 × 150 mm) are similar within the same market but vary across the three markets. Also, it was found that the length of the four sizes of timbers was not up to the required 3.66 m long within and across the three surveyed markets. For improving the efficiency of estimators and the accuracy of timber restoration projects, the average length of timber sold across the selected timber markets in the north-central region of Nigeria was established in this paper. Though the analyses
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used in this paper were less rigorous, the objective of the research was achieved. This paper is not only an essential step towards the identification of accurate estimation of timber-related projects but goes further to create awareness among the estimators and renovation contractors on the need to be knowledgeable about the actual sizes of building materials sold in the markets or supplied to site for the execution of any project. In other words, this work will assist in creating more awareness, especially in the process involved in the estimation of timber-related projects. The reason is that the difference in the required length and the actual length available in the market is useful for the preparation of the materials schedule. Hence, an essential contribution of this paper is on the accuracy of cost estimation and preparation of material schedule for timber-related projects, such as roof restructuring and renovation of historical buildings using timber. A major limitation acknowledged in this study was the relatively small sample size. Not all the timber shop owners permitted a physical measurement of the timbers they sell. Future research should replicate this research across other regions of Nigeria. Such endeavor will enable a comparison of the length of timber scantlings sold across Nigerian timber markets. This study offers specific practical implications to the construction estimating professionals such as the Quantity Surveyors. While the literature confirms that the standard length of timber scantlings is 3.66 m long in Nigeria, estimators should also confirm the average length of timber scantling sold in the timber markets. The findings in this study will guide them on the exact length for calculating the number of timber materials required for any timber-related projects. Government agencies responsible for enforcing building standards should, in addition to the quality of materials, regulate the needed sizes of building materials sold in the various markets. Declaration of Competing Interest The authors certify that there is no conflict of interest associated with this manuscript. Acknowledgments The authors thank all the Higher National Diploma students of Federal Polytechnic Nasarawa that participated in the data collection. References [1] A.G. Ahmad, H.F. Abdul-Rahman, Restoration and refurbishment of old city hall, Georgetown, Penang, Malaysia, in: W. Yaowu (Ed.), Proceedings of the International Conference on Construction and Real Estate Management, 2005. [2] A. Akintoye, Analysis of factors influencing project cost estimating practice, Const. Manag. Econ. 18 (2) (20 0 0) 77–89. [3] A. Akintoye, M. Skitmore, Profitability of UK construction contractors, Const. Manag. Econ. 9 (4) (1991) 311–325. [4] N. Atakul, M.J. Thaheem, A. De Marco, Risk management for sustainable restoration of immovable cultural heritage, part 1: PRM framework, J. Cult. Herit. Manag. Sustain. Dev. 4 (2) (2014) 149–165. [5] J.O. Ayeni, Principles of Tendering and Estimating, second ed., Builder’s Magazine Limited, Lagos, 1997. [6] P.A. Bullen, Adaptive reuse, and sustainability of commercial buildings, Facilities 25 (1/2) (2007) 20–31. [7] N. Dann, S. Wood, Tensions and omissions in maintenance management advice for historic buildings, Struct. Surv. 22 (3) (2004) 138–147. [8] R. Fabbri, L. Gabrielli, A.G. Ruggeri, Interactions between restoration and financial analysis: the case of Cuneo War Wounded House, J. Cult. Herit. Manag. Sustain. Dev. 8 (2) (2018) 145–161. [9] B.M. Feilden, Conservation of Historic Buildings, (3rd Ed), Architecture Press, 2003. [10] S.N. Harun, Historical Building Conservation in Malaysia: Experience and Challenges, University Teknologi, MARA Perak, 2011. [11] C. Houchen, A specifier’s guide to timber, Structural Survey 10 (3) (1992) 248–253. [12] W. Killman, S. Tom, L.T. Hong, Restoring and Reconstructing the Malay Timber House, Forest Research Institute Malaysia, Kuala Lumpur, 1994. [13] J. Kleboe, Timber and the Built Environment Conference, Historic Scotland, Edinburgh, 2004. [14] B.T. Lim, F.Y. Ling, C.W. Ibbs, B. Raphael, G. Ofori, Empirical analysis of the determinants of organizational flexibility in the construction business, J. Constr. Eng. Manag. 137 (3) (2010) 225–237. [15] N.K.F. Mustafa, S. Johar, A.G. Ahmad, S.H. Zulkarnain, M.Y.A. Rahman, A.I. Che-Ani, Conservation and repair works for traditional timber mosque in Malaysia: a review on techniques, World Academy of Science, Eng. Technol. 5 (5) (2011) 663–668. [16] P. Oram, The Repair and Maintenance of Historic Buildings: A Brief Guide for owners, Architects, and Agents, The Northern Ireland Historic Building Council, Belfast, 1994. [17] L.K. Quah, Comparative variability in tender bids for refurbishment and new build work, Construct. Manag. Econ. 10 (3) (1992) 263–269. [18] J. Reyers, J. Mansfield, The assessment of risk in conservation refurbishment projects, Struct. Surv. 19 (5) (2001) 238–244. [19] U. Sekaran, R. Bougie, Research Methods for Business: A Skill-Building Approach, John Wiley & Sons, 2013. [20] W.L. Woon, L.Y. Mui, Elemental cost for building conservation worked in Malaysia, Struct. Surv. 28 (5) (2010) 408–419. [21] U.K. Zolkafli, Z. Yahya, N. Zakaria, F.W. Akashah, A.S. Ali, Restoration of historical timber building: a Malaysian case study, Struct. Surv. 33 (4/5) (2015) 309–321.