Lesson Notes By Weeks and Term v4 - SHS 2

Lesson Video

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Performance objectives

• Define substructure and superstructure.
• Identify and describe different types of walls.
• Discuss the functions of walls in a building.
• Apply critical thinking to wall types in different contexts.

Lesson summary

Welcome, future technicians and engineers! Today, we are moving from the foundation (the substructure) to the parts of a building we see and live in every day: the superstructure. The most important vertical elements of the superstructure are the walls. Think about your own home, our school, or the community clinic. Walls do more than just hold up the roof; they give us privacy, protect us from the sun and rain, and create the spaces where we live our lives. Understanding how walls are built, what they are made of, and the jobs they do is fundamental to building safe, comfortable, and durable structures in Ghana.

Lesson notes

This section provides the core knowledge for our lesson on wall construction. A. What is a Wall?

A wall is a continuous, vertical structure, usually solid, that defines and encloses an area. It is a primary component of the superstructure, which is the part of the building constructed above the foundation or ground level. B. The Main Functions of Walls

Walls serve two main categories of functions: Primary (or structural) functions and Secondary (or service/protective) functions. Primary (Structural) Functions: These are the functions related to the strength and stability of the building. Enclosing Space: The most basic function. Walls create the rooms and define the boundary of a building, separating the inside from the outside. Supporting Loads: Walls can be designed to carry the weight of the roof, floors above, and even other walls. This is transferred down to the foundation. This is the job of a load-bearing wall. Providing Stability: Walls resist lateral (sideways) forces like strong winds, which are common during the rainy season in Ghana, ensuring the building does not collapse. Secondary (Service/Protective) Functions: These functions relate to the comfort, safety, and usability of the building for its occupants. Weather Protection: Walls are the main barrier against rain, direct sunlight (heat), and dust. A well-built wall keeps the interior dry and cool. Privacy: Walls provide visual and sound separation between different rooms (e.g., bedrooms, living room) and between different homes. Security: Walls form a physical barrier to prevent unauthorised entry by intruders. Thermal Insulation: Walls help to regulate the temperature inside a building. In Ghana, a good wall (like one made from traditional earth or thick sandcrete blocks) can keep the interior cool during a hot afternoon. Sound Insulation: Walls reduce the transmission of noise from outside (e.g., traffic, neighbours) and between rooms. Fire Resistance: Walls, especially those made from concrete or bricks, can help contain a fire and prevent it from spreading quickly to other parts of the building. Aesthetics: Walls provide the surface for finishes like plastering, painting, and tiling, contributing to the beauty of a building. C. Types of Walls

We can classify walls in two main ways: by their function (the job they do) and by the material they are made from. Classification by Function: Load-Bearing Walls: Definition: These are structural walls that support loads from the roof and/or upper floors and transfer these loads to the foundation. Characteristics: They are usually thicker and stronger than other walls. In a typical Ghanaian single-storey house made of sandcrete blocks, the external walls are almost always load-bearing. Analogy: Think of a person carrying a heavy basket of yams on their head. Their spine and legs are "load-bearing." Non-Load-Bearing Walls: Definition: These walls only support their own weight and do not carry any load from the roof or floors above. Their main job is to divide space. Example: In a modern building with a concrete frame (columns and beams), the frame carries all the load. The walls simply fill the gaps. The thin walls used to separate a bedroom from a bathroom are non-load-bearing. Sub-type: Partition Walls: These are internal, non-load-bearing walls used to create separate rooms or spaces. Retaining Walls: Definition: A wall built to hold back or "retain" soil or earth. Use in Ghana: You often see these on hilly plots, like in the Aburi or Kwahu areas, to create a flat area for building and to prevent soil erosion. They are also used along roadsides. They must be very strong to resist the immense pressure from the soil behind them. Curtain Walls: Definition: An outer, non-load-bearing wall fixed to the main building frame. It acts like a "curtain" hanging on the building. Use in Ghana: Common in modern high-rise buildings in Accra, Kumasi, and Takoradi. They are often made of glass and aluminium and are chosen for their light weight and modern appearance. Classification by Material: Sandcrete / Concrete Block Walls: Description: The most common type of wall construction in Ghana today. Made from blocks composed of sand, cement, and water. Common Sizes: 150mm (6 inches) for internal non-load-bearing walls and 200mm (8 inches) or 225mm (9 inches) for external and load-bearing walls. Advantages: Strong, durable, relatively fast to build. Disadvantages: Poor thermal insulation (can make rooms hot if not shaded), and the cost of cement can be high. Brick (Burnt Clay) Walls: Description: Made from clay that has been moulded and fired in a kiln. Advantages: Very durable, good fire resistance, and have a beautiful reddish appearance that often doesn't require painting. They also have better thermal properties than sandcrete blocks. Disadvantages: Can be more expensive and labour-intensive than blockwork. Rammed Earth Walls (Atakpame): Description: A traditional and sustainable method common in many parts of Ghana, especially the northern regions. A mixture of laterite soil (clay and sand), water, and sometimes a stabiliser like a small amount of cement is compacted in layers between temporary formwork. Advantages: Excellent thermal insulation (keeps interiors very cool), low cost (uses local materials), and environmentally friendly. Disadvantages: Can be susceptible to water damage if not properly protected by a good roof overhang and foundation, and construction can be slow. Timber / Wood Walls: Description: Walls constructed with a wooden frame and covered with planks or panels. Use in Ghana: Not very common for entire houses today due to issues with termites and durability in the humid climate, but used for internal partitions, guesthouses, or as a decorative feature (cladding).

Evaluation guide

• Discuss wall construction.
• Collaboration:
• In structured groups (GESI) ask learners to explain walls as used in the superstructure.
• In structured groups (GESI) ask learners to outline types of walls.