Lesson Notes By Weeks and Term v5 - Grade 10

Lesson Video

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Performance objectives

• Describe components and functions of common roof types.
• Sketch and label door and window frames.
• Explain the purpose of door and window hardware.
• Identify different types of glass and their properties.
• Describe the basic installation of door and window frames.

Lesson summary

In Civil Technology, understanding roofs, doors, and windows is absolutely fundamental. These elements are not just about aesthetics; they are crucial for the structural integrity, security, weather protection, and energy efficiency of any building. Think about the informal settlements, formal houses, schools, and community centers around South Africa – each relies on these components for shelter and functionality. This knowledge is directly applicable if you aspire to become a builder, architect, technician, or any role involved in the construction industry, which is a significant contributor to the South African economy.

Lesson notes

2.1 Roofs: Basic Construction Details Roofs protect buildings from the elements (rain, sun, wind) and provide structural stability. Common roof types in South Africa include gable, hip, flat, and lean-to roofs. The choice of roof depends on aesthetic preferences, budget, climate, and structural requirements.

Gable Roof: This is a simple, pitched roof with two sloping sides that meet at a ridge.

Components:* Rafters (sloping structural members), ridge board (horizontal beam at the apex), purlins (horizontal beams supporting the rafters), roof covering (tiles, sheets), fascia board (covers the ends of the rafters), barge board (covers the gable end).

Construction Details:* Rafters are typically spaced evenly and connected to the ridge board at the top and wall plate at the bottom. Purlins provide intermediate support, particularly for long rafters. The roof covering is attached to battens or brandering which are fixed to the rafters or purlins.

Hip Roof: This roof has sloping sides that meet at hips (external angles) and a ridge. It offers better wind resistance than a gable roof.

Components:* Hip rafters (diagonal rafters forming the hip), common rafters (similar to gable roof rafters), jack rafters (shortened rafters that meet the hip rafter), ridge board, purlins, roof covering.

Construction Details:* Hip rafters are crucial for supporting the roof structure. Jack rafters connect the wall plate to the hip rafter.

Flat Roof: This roof has a very slight slope for drainage. It's common in modern designs but requires effective waterproofing.

Components:* Roof deck (concrete slab or timber frame), waterproofing membrane (bitumen, PVC), insulation, drainage system (gutters, downpipes).

Construction Details:* Proper waterproofing is essential to prevent leaks. A slight slope (1-2 degrees) ensures water runoff.

Lean-to Roof: This roof has a single sloping side, often attached to an existing wall.

Components:* Rafters, wall plate, roof covering.

Construction Details:* The rafters are supported by the wall plate at the bottom and the existing wall at the top.

Example: Imagine building a small storeroom in your backyard with a lean-to roof. You need to determine the length of the rafters based on the desired slope and height difference between the wall plate and the top of the existing wall. This involves basic trigonometry (SOH CAH TOA) to calculate the rafter length. 2.2 Doors: Basic Construction Details Doors provide access and security to a building. They consist of a door leaf (the moving part) and a door frame (the fixed part). Door frames can be made of wood or steel.

Wooden Door Frame: Components:* Head (top horizontal member), jambs (vertical side members), sill (bottom horizontal member in some cases), hinges, strike plate (receives the latch), door stop (prevents the door from swinging too far).

Construction Details:* The head and jambs are joined together using mortise and tenon joints or screws. The frame is then fixed to the wall opening using nails or screws and shims (thin pieces of wood used to level the frame).

Steel Door Frame: Components:* Similar to wooden frames (head, jambs, sill). Often made of hollow steel sections.

Construction Details:* Steel frames are typically welded together. They are stronger and more durable than wooden frames but can be more expensive.

Example: Consider replacing an old wooden door frame in a house. You need to measure the existing opening accurately to ensure the new frame fits properly. Also, you need to ensure the frame is plumb (perfectly vertical) and level before fixing it to the wall. A spirit level is crucial for this process. 2.3 Windows: Basic Construction Details Windows provide light, ventilation, and a view to the outside. Like doors, they consist of a window frame and a window sash (the moving part containing the glass). Window frames are often made of steel, aluminum, wood or PV

C. Steel Window Frame: Components:* Head, jambs, sill, mullions (vertical dividers), transoms (horizontal dividers), hinges, handles, latches.

Construction Details:* Steel window frames are often manufactured as complete units. They are strong and durable. The glass is fixed into the frame using putty or glazing beads.

Types of Glass: Float Glass:** Standard, clear glass.

Safety Glass (Tempered Glass):* Stronger than float glass and shatters into small, blunt pieces instead of sharp shards. Important for safety, especially in doors and low-level windows.

Laminated Glass:** Two or more layers of glass bonded together with a plastic interlayer. It remains intact even when broken.

Tinted Glass:** Glass that has been treated to reduce the amount of light and heat that passes through it. Useful for energy efficiency.

Example: A school requires new windows. The choice between safety glass and float glass is crucial for the safety of the students. Safety glass is preferable in areas where the windows are likely to be impacted, such as playgrounds.