Lesson Notes By Weeks and Term v5 - Grade 11

Lesson Video

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Performance objectives

• Interpret symbols on foundational plans and elevations.
• Draw a foundational plan for a simple building.
• Draw an elevation for a simple building.
• Relate these drawings to the actual construction process.
• Apply SANS 10400-A standards to your drawings.

Lesson summary

This week, we delve deeper into civil drawing, specifically focusing on foundational plans and elevations. Understanding these drawings is absolutely crucial for anyone involved in building and construction, from architects and engineers to construction workers and even homeowners planning renovations. Foundational plans depict the layout of the building's base, including footings, walls, and other structural elements below ground level, while elevations show the vertical arrangement and external appearance of the building.

Lesson notes

2.1 Foundational Plan: The Blueprint Below Ground The foundational plan, also known as a footing plan or basement plan (if applicable), is a horizontal section through the building below the ground level. It reveals critical structural details necessary for ensuring the building's stability.

Key Elements: Footings: These are the widened bases of walls and columns that distribute the building's load onto the soil. Different types of footings exist, including strip footings (for walls), pad footings (for columns), and raft foundations (for weak soils). The size and type of footing are determined by soil conditions and building loads. SANS 10400-A specifies minimum requirements for footing design in South Africa.

Walls: The foundational plan shows the position and thickness of all load-bearing walls, as well as any internal walls that extend below ground level. Wall thicknesses are crucial for structural integrity.

Damp-Proof Course (DPC): This is a horizontal barrier of waterproof material (e.g., bitumen felt or plastic) placed in the wall just above ground level to prevent rising damp. It is essential in South Africa's diverse climate, especially in areas with high rainfall or groundwater.

Reinforcement: Steel reinforcement bars (rebar) within the footings and walls are often indicated. The amount and arrangement of rebar depend on the load requirements.

Ground Level (GL): This is a crucial reference point, indicated by a dashed line. Everything below the GL is represented in the foundational plan.

Drainage: Perimeter drains are often included in foundational plans to channel water away from the foundations, preventing water damage.

Symbols and Conventions: Footings are typically represented by thicker lines than walls. DPC is shown as a thin, dark line. Reinforcement bars are indicated using specific symbols and spacing annotations. The GL is marked with a dashed line and labelled. Material hatching (e.g., concrete, brick) may be used to differentiate elements. 2.2 Elevation: The Building's Face The elevation drawing is an orthographic projection showing one side of the building. It provides a view of the building's external features and vertical dimensions.

Key Elements: Ground Level (GL): This is the same reference point as in the foundational plan.

Floor Level (FL): Indicates the height of the finished floor above ground level.

Wall Heights: The overall height of the building, as well as the height of individual walls, is shown.

Roof Details: The shape, pitch, and overhang of the roof are clearly depicted.

Openings: The size, position, and type of windows and doors are shown.

Architectural Features: Any decorative elements, such as balconies, verandas, or cladding, are included.

Levels of the building: Clear distinction between ground floor and any upper floors.

Symbols and Conventions: Different line weights are used to distinguish between foreground and background elements. Hidden lines (representing features behind other elements) are shown as dashed lines. Hatching or shading may be used to indicate different materials or textures. Dimensions are clearly labelled to indicate sizes and heights. 2.3 Relationship Between Foundational Plan and Elevation: The foundational plan and elevation drawings are intimately linked. The foundational plan shows the base upon which the elevation is built. The GL is the common reference point that connects the two drawings. The wall thicknesses in the foundational plan correspond to the wall thicknesses shown in the elevation. Dimensions must be consistent between the two. Understanding this relationship is vital for accurate and coordinated construction. 2.4 Worked Examples (Foundational Plan)

Example 1: Drawing a Strip Footing Let's say we need to draw a strip footing for a wall that is 230mm thick. SANS 10400-A provides guidelines for minimum footing widths and depths based on soil conditions. Let's assume we are using a minimum footing width of 600mm and a depth of 300mm (these values are for illustrative purposes only; actual values must be calculated by a qualified engineer). The DPC is placed 150mm above ground level. Draw the ground level (GL) as a dashed line. Draw the footing as a rectangle below the GL, 600mm wide and 300mm deep. Draw the wall above the footing, centered on the footing, and 230mm thick. Draw the DPC as a thin, dark line 150mm above the GL, embedded within the wall. Add dimensions to indicate the width and depth of the footing, the wall thickness, and the height of the DPC above the G

L. Add hatching to indicate concrete.

Example 2: Drawing a Pad Footing Imagine a column supporting a large roof needs a pad footing. Let's assume the pad footing is 1m x 1m square, and 400mm deep. Draw the ground level (GL) as a dashed line. Draw the pad footing as a square below the GL, 1000mm x 1000mm and 400mm deep. Draw the column above the footing, centered on the footing. The column dimensions will depend on the structural design.