Methods of Setting Out in Building Construction

Setting out, also known as "staking out" or "laying out," is a crucial process in building construction that involves transferring the architect's plans to the ground, ensuring the construction is built in the correct location and to the specified dimensions. Below are the primary methods used for setting out in building construction:

1. Baseline Method

• Description: The baseline method involves establishing a baseline, typically a straight line, between two fixed points on the site. This line serves as a reference for all other measurements.
• Usage: It's commonly used in road construction and other linear projects. The baseline can be extended to mark out the entire structure by measuring perpendicular distances from the baseline.

2. Grid Method

• Description: The grid method involves dividing the site into a grid of squares or rectangles, marked by pegs or stakes. The grid lines correspond to the centerlines of walls, columns, or other structural elements.
• Usage: This method is particularly useful for complex buildings with multiple intersecting walls and varying levels. It helps ensure accuracy and easy referencing during construction.

3. Radiation Method

• Description: The radiation method involves using a central reference point (often the building’s center) and measuring outwards in different directions using angles and distances. These measurements are usually taken with a theodolite or total station.
• Usage: Ideal for curved or circular structures where gridlines are impractical, like domes or circular columns.

4. Offset Method

• Description: The offset method involves marking points on the ground by measuring perpendicular distances (offsets) from a known line, such as a baseline or boundary. These points are then connected to establish the layout.
• Usage: Commonly used when the site is irregular or when setting out features like roads and curved structures.

5. Intersection Method

• Description: In this method, two or more known points are used to determine the position of a new point by creating intersecting lines from these known points.
• Usage: It's often used in setting out points that are difficult to reach directly, such as corners of large structures or inaccessible areas.

6. Tachometry Method

• Description: Tachometry is a rapid survey method using a tachometer, a type of theodolite, to measure both horizontal and vertical distances. This method is efficient for setting out in hilly or uneven terrain.
• Usage: It's used where the ground is uneven, and accurate measurements of horizontal and vertical distances are required.

7. GPS and Total Station

• Description: Modern technology has introduced GPS and total station devices that allow for high-precision setting out. These devices can automatically calculate and set out points using digital maps and satellite data.
• Usage: Widely used in large-scale projects for accuracy and speed, especially in locations where traditional methods are difficult to implement.

8. Profile Boards

• Description: Profile boards are horizontal boards set at a specific height, onto which the positions of walls and other structural elements are marked. These boards act as guides for excavation and construction.
• Usage: Useful for marking the depth of excavation and maintaining a consistent level during the construction of foundations.

Summary

Setting out is a critical first step in construction, requiring accuracy and precision to ensure that the structure is built correctly. The method chosen depends on the nature of the project, the site conditions, and the complexity of the design. Each method ensures that the building is constructed according to the specified plans, preventing costly mistakes and rework.

Thu Aug 8, 2024