Lesson Notes By Weeks and Term v5 - Grade 11

Lesson Video

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Performance objectives

• Explain superstructure components (walls, lintels, roof)
• Describe different types of wall finishes
• Calculate material quantities for finishes
• Identify common flooring materials and methods
• Understand quality control and safety measures

Lesson summary

This week, we delve into the fascinating world of superstructures and finishes in construction. The superstructure is the part of the building above the foundation or ground level. It’s what you see and interact with daily – the walls, floors, roof, and all the internal elements that make a building habitable and functional. Finishes are the materials applied to the superstructure’s surfaces to provide aesthetic appeal, protection, and functionality (like flooring, tiling, plastering, and painting). Understanding these processes is crucial because they directly impact the quality, safety, and longevity of buildings we live, work, and play in across South Africa.

Lesson notes

2. 1. Superstructure Components and Construction Processes: The superstructure is essentially the skeleton and skin of the building above the ground. Let's break down the main components for a typical single-story residential dwelling: Walls: Walls can be load-bearing (supporting the roof and upper floors, if any) or non-load-bearing (simply dividing spaces). In South Africa, common wall materials include: Brick: Clay bricks are durable and provide good thermal insulation. They are laid in mortar using various bond patterns (e.g., stretcher bond, English bond). Construction involves laying the first course of bricks on the damp-proof course (DPC), ensuring alignment and level, and then building upwards course by course, checking for plumb (verticality) and level.

Concrete Blocks (Blocks): Concrete blocks are larger than bricks, making wall construction faster. They are also generally cheaper. Hollow concrete blocks can be used for improved insulation.

Example: Consider building a brick wall. The mortar mix is crucial (typically cement, lime, and sand). Too much cement makes it brittle, too little makes it weak. The bricks must be soaked in water before laying to prevent them from absorbing moisture from the mortar, which can lead to cracking.

Lintels: Lintels are horizontal structural members placed over openings (doors and windows) to support the weight of the wall above.

They can be: Reinforced Concrete Lintels: These are cast in-situ (on-site) or pre-cast. They are strong and durable. Reinforcement (steel bars) is essential to handle tensile stresses.

Steel Lintels: These are commonly used for smaller openings. They are readily available and easy to install. They require protection against corrosion (rust).

Example: When installing a reinforced concrete lintel, ensure it extends at least 150mm beyond the opening on each side (bearing length). The reinforcement must be properly tied and positioned within the formwork before pouring concrete. Use the correct concrete mix and allow it to cure properly.

Roof Structure: The roof protects the building from the elements.

Common roof types in South Africa include: Gable Roof: A simple roof with two sloping sides meeting at a ridge.

Hip Roof: A roof with slopes on all four sides.

Flat Roof: A roof with a slight slope for drainage (common in modern designs).

Roofing Materials: Tiles (concrete or clay), corrugated iron (IBR sheets), and thatch (in specific areas).

Construction: The roof structure typically consists of trusses (pre-fabricated triangular frames), rafters (inclined beams), purlins (horizontal beams supporting the rafters), and battens (horizontal strips to which the roofing material is attached).

Example: Installing roof trusses requires careful planning and execution. Ensure they are properly spaced according to the manufacturer's specifications. Use appropriate fasteners (nails or screws) to secure the trusses to the wall plate. Bracing is essential to prevent lateral movement and collapse. 2.

2. Wall Finishes: Wall finishes provide aesthetic appeal, protect the wall from the elements, and improve insulation.

Plastering: Applying a layer of mortar (cement, lime, and sand) to a brick or block wall to create a smooth and even surface.

The process involves: Preparation: Cleaning the wall surface and applying a bonding agent (e.g., plaster primer).

Application: Applying the plaster in layers (usually two coats – a scratch coat and a finishing coat).

Finishing: Smoothing the surface with a trowel to achieve the desired texture.

Example: When plastering, ensure the wall surface is clean and free from dust and debris. Use a gauge rod to ensure the plaster is applied to the correct thickness. Damp cure the plaster for several days to prevent cracking.

Cladding: Applying a non-structural layer of material to the wall for aesthetic or protective purposes.

Examples include: Face Brick: Using decorative bricks for the outer layer of the wall.

Stone Cladding: Applying thin slices of natural stone to the wall.

Wood Cladding: Applying wooden planks or panels to the wall (requires proper treatment to prevent rot and insect infestation).

Example: When installing wood cladding, ensure the wood is properly treated with a preservative and is securely fastened to the wall using appropriate fixings. Provide proper ventilation behind the cladding to prevent moisture buildup.

Tiling: Applying ceramic or porcelain tiles to walls, typically in bathrooms and kitchens.

The process involves: Preparation: Ensuring the wall surface is level and applying a waterproofing membrane.

Adhesive: Applying tile adhesive to the wall and the back of the tiles.

Laying: Positioning the tiles and using spacers to ensure uniform gaps.

Grouting: Filling the gaps between the tiles with grout.

Example: When tiling, use a notched trowel to apply the adhesive evenly. Ensure the tiles are properly aligned and leveled. Clean excess grout from the tile surface before it hardens. 2.3.