Lesson Notes By Weeks and Term v5 - Grade 10

Lesson Video

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Performance objectives

• Describe the components of a pitched roof.
• Explain the differences between various door and window types.
• Identify common frame materials and their properties.
• Outline the basic steps for installing a window frame.
• Sketch a simple roof-to-wall waterproofing detail (flashing).

Lesson summary

This week, we delve into the fundamental building blocks that provide shelter, security, and natural light to our homes and buildings: roofs, doors, and windows. Understanding the basic construction details of these elements is crucial for anyone aspiring to be involved in the construction industry, whether as a builder, architect, engineer, or even a homeowner wanting to understand the integrity of their dwelling. In South Africa, with its diverse climate and housing styles, knowing how these components are constructed to withstand the elements and provide comfortable living spaces is vital.

Lesson notes

2.1 Roofs: Roofs are essential for protecting buildings from the elements, including rain, wind, and sun. The type of roof construction depends on factors like climate, aesthetics, and cost. We'll focus on pitched roofs as they are common in South Africa.

Pitched Roof Components: Rafters: These are structural members that span from the ridge (the highest point of the roof) to the wall plate (the support along the top of the wall). They are typically made of timber or steel. The spacing between rafters is crucial for structural integrity; typically, spacing should follow the engineer's specification for the rafter size and the roof sheeting to be used. Rafter size depends on the rafter span, the type of roofing and the rafter spacing.

Purlins: These horizontal members run perpendicular to the rafters and provide intermediate support, preventing the rafters from sagging. Purlins are supported by trusses or load-bearing walls.

Roof Covering: This is the outermost layer that provides weather protection.

Common materials include: Concrete Tiles: Durable, fire-resistant, and aesthetically versatile.

However, they are heavy and require a strong supporting structure.

Metal Sheets (Corrugated Iron/Zinc): Lightweight, relatively inexpensive, and easy to install.

However, they can be noisy during rain and require corrosion protection.

Asbestos Cement Sheets (Avoid): While historically used, asbestos is a health hazard and its use is now restricted or banned in many areas. Do not use asbestos cement sheets.

Thatch: A traditional material, providing excellent insulation and a natural look. Requires regular maintenance and is susceptible to fire.

Underlay (Waterproof Membrane): This layer is placed beneath the roof covering to provide an extra layer of waterproofing and prevent moisture from penetrating the roof structure. It also helps to improve insulation.

Battens: These are thin strips of timber that are fixed horizontally to the rafters, providing a fixing point for the roof covering (e.g., tiles).

Fascia Board: A horizontal board fixed to the rafter ends to provide a neat finish and a fixing point for gutters.

Soffit: The underside of the eaves, which can be ventilated to prevent moisture build-up in the roof space.

Flashing: Metal strips used to seal joints between the roof and walls or other roof features (e.g., chimneys) to prevent water ingress.

Roof Pitch: The angle of the roof slope. Steeper pitches shed water more effectively but require more materials. Shallower pitches are more aesthetically pleasing to some and allow for larger roof spaces but can be more prone to leaks if not properly constructed. 2.2 Doors: Doors provide access and security. They come in various types and materials.

Types of Doors: Hinged Doors: The most common type, swinging on hinges attached to a door frame. Can be single or double doors.

Sliding Doors: Slide horizontally along a track, saving space. Popular for patios and balconies. Can be noisy.

Folding Doors (Concertina Doors): Fold into panels when opened, creating a wide opening.

Pivot Doors: Rotate on a pivot point rather than hinges, creating a dramatic entrance.

Door Components: Door Frame: The surrounding structure that supports the door.

Door Leaf (Door Slab): The main part of the door that swings or slides.

Hinges: Allow the door to swing open and closed.

Locks and Handles: Provide security and operation.

Threshold: The bottom part of the door frame.

Door Frame Materials: Timber: Traditional, aesthetically pleasing, and can be easily worked.

However, susceptible to rot and insect damage if not properly treated.

Steel: Strong and durable, providing good security. Can be prone to rust if not properly coated.

Aluminium: Lightweight, corrosion-resistant, and requires little maintenance. uPVC (Unplasticized Polyvinyl Chloride): Low maintenance, good insulation, and weather-resistant. 2.3 Windows: Windows provide natural light, ventilation, and views.

Types of Windows: Casement Windows: Hinged on one side and swing outwards or inwards.

Sliding Windows: Slide horizontally along a track.

Fixed Windows: Do not open and are used for providing light and views.

Awning Windows: Hinged at the top and swing outwards.

Hopper Windows: Hinged at the bottom and swing inwards.

Window Components: Window Frame: The surrounding structure that supports the window.

Sash: The movable part of the window that holds the glass.

Glass (Glazing): Single, double, or triple-paned for insulation.

Hardware: Locks, handles, and hinges.

Window Frame Materials: Similar to door frame materials (timber, steel, aluminium, uPVC) with similar advantages and disadvantages. 2.4 Installation of a Window Frame: Prepare the Opening: Ensure the opening is the correct size and square.

Position the Frame: Place the frame in the opening, ensuring it is level and plumb (vertical).

Secure the Frame: Use shims (thin wedges) to adjust the frame until it is perfectly aligned.