Some useful methods for estimating building works
The following method are useful for working out various building quantities like earth work, foundation concrete, brickwork in plinth and super structure etc.
a) Long wall – short wall method
b) Centre line method.
c) Partly centre line and short wall method.
a) Long wall-short wall method: Under this method, the wall along the length of room is treated as long wall whereas the wall that is situated vertically to long wall is called short wall. To find out the length of long wall or short wall, initially compute the length of centre line for separate walls. Then compute the length of long wall, (out to out) once half breadth at each end is added to its centre line length. Therefore, the length of short wall is calculated into in and is built by subtracting half breadth from its centre line length at each end. The length of long wall normally declines from earth work to brick work in super structure whereas the short wall enlarges. In order to obtain quantities, multiply these lengths with breadth and depth.
b) Centre line method: This method is most effective for walls having equivalent cross sections. In order to obtain the total quantity at once, multiply total centre line length with breadth and depth of relevant item. If cross walls or partitions or verandah walls are connected with main wall, the centre line the length of the centre line is decreased by half of breadth for each junction. While computing total centre line length, there should be clear ideas on such junction or joints. This type of estimating method is considered as most perfect and fast.
c) Partly centre line and partly cross wall method: This method is effective if the exterior (i.e., around the building) wall contains one thickness and the internal walls contain dissimilar thicknesses. Under this situation, centre line method is implemented to external walls and long wall-short wall method is applied to internal walls. This method is ideal for the walls having diverse thicknesses and diverse level of foundations. For this purpose, all Engineering departments are applying this method.
Article Source: theconstructor.org