The extensive use of Sandcrete blocks (SBs) for residential buildings as compared to interlocking bricks (IBs) has significantly increased its cost and has therefore affected the cost of housing delivery in Ghana. The research aimed at comparing the cost of SBs and IBs for residential buildings in Ghana. The study adopted qualitative and physical measurement methods of data collection on a two bedroom self–contain floor plan building. The findings revealed that lesser construction time was required for IBs. It was also established from the study that a total cost of GH¢14,268.54 and GH¢ 18,869.64 were observed for IBs and SBs respectively. The difference in cost of SBs were found to be GH¢4,601.10, representing 24.38%. The consequence is reduction in laborer force, limited finishing time and minimum running cost, without compromising the aesthetic and strength value. The study therefore recommends the use of IBs for prospective building developers, entrepreneurs and individuals due to its cost saving, time and running cost.

Keywords: affordable housing, environmental friendliness, design flexibility, housing policy, housing problems, population, shelter

The Ghanaian populace is facing serious housing problems, particularly for the poor who represent the majority of the Ghanaian population. Hence, adequate shelter is one of the most important basic human needs. Adewole¹ posited that interlocking bricks are considered to have high energy efficiency, structural stability and a high acceptability index in terms of aesthetic as against the use of sandcrete blocks. Adedeji² & Arayela³ opined that building materials constitutes the main factors and the largest single input in housing construction; restrict the supply of housing account for between 50–60 percent of building cost. Interlocking bricks (IB) have always been in use to a lesser extent; however, according to Ogunsemi,⁴ extensive studies on the technology appeared after the first ecological–villages came into being. The Interlocking Brick (IB) is a technology that developed the idea of dry stacking bricks during construction method known as mortar–less bricks. Sandcrete blocks as indicated by Akeem et al.⁵ is known as a walling unit produced from sand, cement and some water, and it is widely used in Ghana as a walling unit. Cement as a binder remains the most expensive input in the production of sandcrete blocks. The National Housing Policy of Ghana, as indicated by Gidigasu⁶ through the Ministry of Works and Housing in 1986 emphasized the development and use of local building material to contribute to the solution of the housing crises, thereby, reducing the importation of foreign building materials to a minimum. Its widespread use can be attributed to its availability and satisfactory characteristics.⁷

The accumulated housing deficit in Ghana as point out by Mustapha et al.⁸ was due to neglected use of the use of traditional building materials by developers. The influx of foreign building materials and techniques has also been a major problem facing the construction industry in Ghana. However, Nicco–Annan⁹ exposed the high cost and time overruns as well as poor quality of construction materials perceived to be associated with construction product delivery process in Ghana. This can only be resolved when the percentage cost difference in putting up a building using sandcrete blocks and interlocking bricks are known. Sarfoh¹⁰ posited that the cost of housing has soared out of control to the point that only few wealthy Ghanaians can afford to buy a house in the urban core. The paper compared the cost of sandcrete blocks (SBs) and interlocking bricks (IBs) for residential buildings in Ghana.

The quantitative and case study approaches were adopted in this study to determine the comparative cost analysis between interlocking bricks (IBs) and sandcrete blocks (SBs) for residential buildings in Ghana. This was determined through the qualitative approach and physical measurements of a two–bedroom self–contain floor. The physical measurement of a two–bedroom self–contain house was conducted from the foundation through to the beam level. Prices of IBs and SBs were obtained from various building materials shops in the Cape Coast Metropolis in May 2016. The data collected as shown in Tables 1–10 were used to estimate the cost elements. While Tables 11–16 shows the unit costs of interlocking blocks (IBs) and sandcrete blocks (SBs). All these account for the difference between IBs and SBs, as well as their percentage cost difference. The information was also used to compare and contrast the cost benefit analysis in promoting affordable housing in Ghana. Descriptive statistics was used in the analysis of the data.

Interlocking and sandcrete blocks

Both interlocking blocks and sandcrete blocks as shown serve similar purpose.¹¹ The research report further indicated that both interlocking blocks and sandcrete blocks, as shown in Figures 1 and 2 have varied differences and similarities in terms of price, durability, choices, convenience, and their advantages over each other.¹¹ Assiamah et al.¹² in their study of interlocking and sandcrete blocks for building walling systems realized a 50% from the output of the masons when interlocking blocks were used as compared to sandcrete blocks. Material cost for the use of mortar by each mason for both interlocking blocks was lower than sandcrete blocks. Cost of labour also reduced drastically and this result concur with that of Danso et al.¹³ This is in relation to construction of walls. Assiamah et al.,¹² posited that the reduction in cost was due to minimum mortar used during the construction. Assiamah et al.,¹² concluded that the cycle time of bonding blocks in interlocking blocks reduced significantly and subsequently increased the speed of wall construction. Interlocking blocks are also affordable in terms of cost and weather conditions. The use of materials also was cut down significantly and labour cost reduced (Figure 1).

Figure 1 Sandcrete blocks.
Source Ghana Homes Block.¹¹

A research by Ghana Homes Block¹¹ show that the use of interlocking block has reduced drastically due to its limited use in the country. Even Ghana has a clay deposit in all the regions, but non patronization of the products of the industry has resulted to close of the brick industry in Ghana (Figure 2).

Figure 2 Interlocking blocks.
Source Ghana Homes Block.¹¹

The cost estimates for both brick–work and block–work brickwork which comprised of materials, labor and finishing are presented in this section. The area of the building and one brick were found to be 148.71m² and 0.023m respectively. The total number of blocks and bricks were found to be 148m² and 6466. Twenty–five percent (2.5%) waste was added to obtain 162 blocks and 6628 bricks. One bag of cement was required to lay 44bricks within a 1m² area and 9m² area utilized 18bags of cement, 396 of blocks and 6628 of bricks with 0.85 waste. A mix ratio of 1:6 was used with a bag of cement; weighing 50kg and 18 bags of cement utilized 5400kg of aggregate. Water, cement ratio of 0.025 and 50kg, utilized 12.5kg of aggregate. An area of 80m³ with 20% (16 m³) utilized 96m³. The rendering process utilized a mix ratio of 1:4 and 72gallons of water and 63bags of cement (Tables 1-7). Table 4 presents cost of materials for blocks, which comprises of blocks, cement, fine aggregate (sand) and water.

This section presents the discussions on the unit cost and the cost per the area of a single storey two bedroom self–contained using IBs and SBs to determine their cost difference. It begins with the unit cost of IBs and followed by SBs to determine cost of materials and labor. Tables 8–10 present the unit cost of interlocking blocks, comprising of material cost, labor cost and finishes.

Unit cost of sandcrete blocks (SBS)

Tables 11-13 present unit cost of sandcrete blocks, comprising of material cost, labor cost and finishes.

Percentage cost difference between IBS and SBS block for residential buildings

Table 14 presents the percentage cost difference between IBs and SBs.

This section presents the discussions on the cost of element which account for the difference. shows that comparative cost of interlocking bricks and sandcrete blocks were obtained by estimating for the cost of a two bedroom single–storey self–contained building plan excluding the roof and substructure. The prices of interlocking bricks and sandcrete blocks were obtained from the market. Sandcrete blocks (450x225x150) were sold at GH¢ 2.90, whiles interlocking bricks (250x125x100) mm were sold at GH¢ 1.70. The cost includes loading/off–loading and transportation. It was observed from the findings that the use of IBs required only 18 bags of cement for the total of 6,628bricks, while 1,398 SBs required 132 bags of cement for both block–laying works, plastering and rendering for the completion of single–storey two– bedroom self–contained bungalow. The use of IBs required only 5m³ of sand costing GH¢250.00/6m³, while the use of SBs required a total of 22.20m³ for block–laying work, plastering and rendering costing GH¢925.00. Additionally, a gang of one mason plus one laborer may possibly lay between 800–1000 IBs per day, thereby using only 8 days in laying a total of 6,628 IBs with a labor cost of GH¢ 720.00. On the other hand, a gang of 1mason plus 2 labor could rather be used in 18 days in laying 1,398 SBs costing a total of GH¢2,340.00 for labor. In the case of finishing, IBs do not require any painting unless the user for no apparent reason decides to do so. Nonetheless, a chemical known as PVC bond is applied as a polish to the surface which cost GH¢ 3.21 per m², hence a total of GH¢1,357.54 is required for the finishing. On the other hand, GH¢ 5.40 per m² is required for SBs which translates into a total cost of GH¢ 9,353.83 for painting.

Discussion on percentage cost difference between interlocking bricks and sandcrete blocks

The total material cost for IBs was GH¢12,291.00 while SBs was GH¢7,175.81 making a cost and percentage difference of GH¢5,015.19 and 41.14% respectively (Table 14). Labor cost for both IBs and SBs was GH¢720.00 and GH¢2,340.00 which makes the cost difference of GH¢1,620.00 and the percentage cost difference of 69.23%. In the case of finishes, the total cost of IBs was GH¢1,357.54 while SBs was GH¢9,353.83 which also makes the cost and percentage cost difference of GH¢7,996.29 and 85.49%, respectively. On a whole, the total cost of IBs was GH¢14,268.54 while that of SBs was added up to get GH¢ 18,869.64. The finishing cost for IBs was higher than the material cost and least among the three was labor cost. However, the cost difference as well as the percentage cost difference was established to be GH¢4,601.1 and of 24.38%. This shows that constructing with IBs is cheaper than that of SBs. Despite the fact that material cost for IBs is more than SBs, there is also an indication that the labor and finishing cost are more when you consider the use of SBs. Assiamah et al.,¹² has also attested to the fact that interlocking blocks are more economical than sandcrete blocks. They further indicated that have the potential of supporting the affordable housing concept in Ghana.

The results revealed that the cost incurred in the use of interlocking bricks for construction of the proposed two bedroom single–storey self–contained building plan under study was cheaper than using sandcrete blocks for construction of the same building in terms of material and labor cost. Considering the cost elements which account for the difference, the study further revealed that the use of sandcrete blocks requires mortar for the laying of blocks as well as associated non–contributory activities like sorting, taking, breaking, laying and leveling of blocks as well as taking, mixing, laying and spreading of mortar and finally, waiting for materials. All of these affect the cost as well as the net output. Hence, these activities together with the use of mortar are eliminated in the use of interlocking bricks. There is flexibility in the design, environmental friendliness reduction in the time for setting operation and elimination of associated wastage. There is also cost saving in the case of IBs at GH¢14,268.54 and SBs at GH¢ 18,869.64. The percentage in the cost difference was established to be GH¢4,601.1 and of 24.38%, respectively, without compromising the aesthetic and strength quality. Interlocking bricks have been found to be better alternatives to sandcrete blocks and should, therefore, be used to promote affordable housing delivery in Ghana for building developers. This will facilitate cost efficiency and make housing provision available and more affordable.

The authors wish to acknowledge the effort of the laboratory technicians at Building Technology Department, Cape Coast Technical University, Cape Coast. Ghana.

The author declares there is no conflict of interest.

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