Lesson Notes By Weeks and Term v5 - Grade 11

Lesson Video

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Performance objectives

• Describe different superstructure systems.
• Explain the purpose of various walling materials.
• Outline the steps for constructing brick and block walls.
• Identify common wall finishes.
• Explain the importance of quality control and safety.

Lesson summary

This week, we delve into the fascinating world of superstructures and finishes – the parts of a building that rise above ground level and give it its final appearance and functionality. Understanding these construction processes is crucial for any aspiring civil technologist. Imagine designing or overseeing the construction of a new RDP house, a school, or even a shopping mall. The knowledge gained this week will form a solid foundation for understanding how these structures are built, ensuring they are safe, durable, and aesthetically pleasing.

Lesson notes

2. 1. Superstructure Systems The superstructure is the part of a building that is above the ground level (as opposed to the foundation or substructure, which is below). It bears the loads of the building and transfers them to the foundations. Two main types of superstructure systems are prevalent in South Africa: Load-Bearing Wall Construction: This is a traditional method where the walls themselves support the weight of the roof and floors. The walls must be strong and thick enough to handle these loads. This method is commonly used in single-story and low-rise buildings, including many residential homes and RDP houses. Brick and block walls are typical components of this system.

Advantages: Relatively simple to construct, cost-effective for smaller buildings.

Disadvantages: Limited design flexibility (open spaces are restricted), not suitable for high-rise buildings.

Framed Construction: In this system, a frame of steel or reinforced concrete carries the loads, while the walls act as cladding, simply enclosing the space. This is common in larger buildings, commercial structures, and high-rise buildings.

Advantages: Greater design flexibility (allows for large open spaces), suitable for high-rise construction.

Disadvantages: More complex to construct, generally more expensive than load-bearing wall construction. We will focus on load-bearing wall construction this week. 2.

2. Walling Materials Bricks: Bricks are made from clay, shaped, and then fired in a kiln to harden them. They come in various sizes and strengths. Common brick types in South Africa include: Common Clay Bricks (NFP):* Used for general construction where plastering is required.

Face Bricks (FS):* Used where the brickwork is exposed and aesthetic appearance is important.

Engineering Bricks (FBS):* High strength and low water absorption, used in demanding situations such as retaining walls or foundations.

Advantages: Durable, fire-resistant, readily available in many parts of South Africa.

Disadvantages: Can be expensive, require skilled labor for proper construction, contribute to deforestation if firing relies heavily on wood fuel.

Concrete Blocks: Concrete blocks are made from a mixture of cement, sand, and aggregates. They are generally larger than bricks, which can speed up construction.

Advantages: Faster to build with than bricks due to their size, can be reinforced with steel for added strength, readily available, potentially cheaper than bricks (depending on location and material costs).

Disadvantages: Can be less aesthetically pleasing than face bricks, require proper curing to achieve full strength.

Alternative Building Materials: Due to increasing environmental concerns and the need for affordable housing, alternative building materials are gaining popularity in South Africa.

Examples include: Earth Bricks (Adobe):* Made from compressed earth and a stabilizer (e.g., cement, lime).

Advantages: Environmentally friendly (uses local resources), good thermal properties.

Disadvantages: Can be susceptible to erosion in wet climates, require proper protection from moisture.

Sandbag Construction:* Walls are constructed using bags filled with sand or earth.

Advantages: Low cost, uses readily available materials.

Disadvantages: Labor-intensive, requires proper stabilization and protection from UV degradation.

Shipping Containers:* Converted into homes and offices.

Advantages: Recycled, durable, relatively quick to build with.

Disadvantages: Can be expensive to modify, require insulation to regulate temperature. 2.

3. Constructing Brick and Block Walls The key steps in constructing brick or block walls include: Preparing the Foundation: The foundation must be level and strong enough to support the wall.

Mixing Mortar: Mortar is the "glue" that holds the bricks or blocks together. A common mortar mix is 1 part cement to 3 parts sand (1:3).

Important: Use clean, sharp sand and potable water. Mix thoroughly to a workable consistency. Too much water weakens the mortar.

Laying the First Course: This is the most crucial step. Use a spirit level to ensure the first course is perfectly level. Apply a bed of mortar and carefully position each brick or block. Use a string line to maintain a straight line.

Bonding Patterns: Different bonding patterns are used to increase the strength and stability of the wall.

Common patterns include: Stretcher Bond:* The most common pattern, where each brick is laid lengthwise (stretcher) with the vertical joints (perpends) offset in alternate courses.

English Bond:* Alternating courses of stretchers and headers (bricks laid with their ends facing out). This is a stronger bond but requires more bricks.

Flemish Bond:* Each course consists of alternating stretchers and headers.

Plumbing the Wall: As you build, regularly check that the wall is vertical (plumb) using a plumb bob or spirit level.

Raking Joints: The mortar joints can be raked out (removed to a certain depth) while still wet to provide a key for plastering.