When it comes to estimating quantities for building works such as earthwork, foundation concrete, and brickwork, several practical methods are employed. These methods provide a systematic way to calculate the materials required for construction. In this discussion, we will delve into three primary methods: the Long Wall – Short Wall Method, Centreline Method, and the Partly Centre Line and Partly Cross Wall Method.
In the Long Wall – Short Wall Method, each room’s length is considered, with the wall along the length identified as the long wall and the perpendicular wall as the short wall. The calculation involves determining the center line lengths of individual walls. Subsequently, the length of the long wall (out to out) is calculated by adding half the breadth at each end to its center line length. Conversely, the short wall’s length is obtained by deducting half the breadth from its center line length at each end. The length of the long wall typically decreases from earthwork to brickwork in the superstructure, while the short wall lengths increase. Multiplying these lengths by breadth and depth provides the required quantities.
The Centre Line Method is well-suited for walls with similar cross-sections. Here, the total center line length is multiplied by the breadth and depth of the respective item to obtain the total quantity at once. Challenges arise when cross walls, partitions, or verandah walls intersect with the main wall, as the center line length is reduced by half of the breadth for each junction. Despite this, estimates generated using this method are considered highly accurate and efficient.
The Partly Centre Line and Partly Cross Wall Method find application when external walls around the building have a consistent thickness, while internal walls exhibit varying thicknesses. In such scenarios, the center line method is applied to external walls, and the Long Wall – Short Wall Method is employed for internal walls. This method accommodates different wall thicknesses and foundation levels, making it a preferred choice for various engineering departments.
By understanding these practical methods, construction professionals can streamline the estimation process, ensuring accuracy and efficiency in planning and executing building projects.