Lesson Notes By Weeks and Term v4 - SHS 2

Lesson Video

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Performance objectives

• Define substructure and superstructure.
• Explain what setting out is and why it's necessary.
• Identify different methods of setting out.
• Understand how to create a right angle using the 3-4-5 method.

Lesson summary

Have you ever passed a new building site and seen workers with strings, wooden pegs, and measuring tapes, carefully marking out lines on the ground before any digging starts? That important process is called Setting Out. It is the very first practical step in constructing any building, from a simple single room in your village to a large shopping mall in Accra. In Ghana, where many of us dream of building our own homes, understanding setting out is crucial. A small mistake at this stage can lead to crooked walls, a poorly fitting roof, wasted money, and even serious arguments with neighbours over land boundaries.

Lesson notes

2.1 What is Setting Out?

Setting Out is the process of transferring the design of a building from the architectural drawings (the plan) onto the ground itself. It involves marking out the exact position, size, and shape of the building's foundation and walls on the site.

Think of it this way: An architect draws the house on paper. The builder's job is to "draw" that same house, full-size, on the plot of land using tools like strings, pegs, and lime powder. These lines will guide the workers on exactly where to dig the trenches for the foundation. 2.2 Why is Setting Out so Important?

Carrying out this process accurately is non-negotiable for several critical reasons: Ensures Accuracy: It guarantees that the building constructed on the ground has the exact same dimensions (length, width) as specified in the architect's plan. Without it, rooms could be smaller or larger than intended. Correct Positioning and Avoiding Disputes: It places the building in the correct location on the plot of land. This is vital for respecting property boundaries. In Ghana, many land litigation cases ("court cases") between neighbours happen because a building was constructed too close to or on the neighbour's land. Proper setting out respects the required setbacks (the minimum distance required by the District Assembly between your building and the boundary line). Achieves "Squareness": It ensures that all corners of the building are perfect right angles (90°). If the corners are not square, it will create major problems later with laying floor tiles, plastering walls, and especially, fitting the roof trusses. A building that is not square is structurally weaker and looks unprofessional. Guides Excavation: The lines from setting out act as a clear guide for the labourers or excavator operators, showing them exactly where to dig the foundation trenches and to what width. This prevents wasted effort and ensures the foundation is placed correctly. 2.3 Tools and Equipment for Setting Out

Evaluation guide

• Explain what setting out is.
• Communication: Organise whole Class and ask learners to explain the meaning of
• setting out and discuss the reasons why setting out of a building has to be done.
• understanding