Correct Answer - Option 4 : i, ii and iii
Methods of estimation are as follows:
1. The centreline method:
- It is suitable for walls of similar cross-sections. Here the total centerline length is multiplied by the breadth and depth of the respective item to get the total quantity at a time.
- When cross walls or partitions walls join with the main wall, the centerline length gets reduced by half of the breadth for each junction i.e. (2 × half of the thickness of the wall = thickness of the wall).
- Such junctions or joints are studied carefully while calculating total centerline length.
The estimates prepared by this method are the most accurate and quick and they can be used in any shape of the structure.
2. Long Wall and Short Wall method:
- In this method, the wall along the length of the room is considered to be a long wall while the wall perpendicular to the long wall is said to be a short wall.
- To get the length of the longwall or short wall, calculate first the centerline lengths of individual walls. Then the length of the longwall, (out to out) may be calculated after adding half breadth at each end to its centerline length.
- Thus the length of the short wall is measured into in and may be found by deducting half breadth from its centerline length at each end. The length of the longwall usually decreases from earthwork to brickwork in superstructure while the short wall increases.
- These lengths are multiplied by breadth and depth to get quantities