Lesson Notes By Weeks and Term v5 - Grade 10

Lesson Video

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Performance objectives

• Identify common symbols and abbreviations on plans.
• Differentiate between plan views, elevations, and sections.
• Determine dimensions and specifications from plans.
• Explain the purpose of different line types.
• Calculate basic quantities like wall length or room area.

Lesson summary

This week, we delve deeper into the fascinating world of civil drawings and building plans. Understanding these plans is fundamental to any construction project, from building a RDP house to constructing a large shopping mall. Without accurate and detailed plans, projects can face delays, cost overruns, and even structural failures. In the South African context, where infrastructure development is crucial for economic growth and social upliftment, the ability to interpret and utilize building plans is a highly valuable skill. Imagine being able to understand the plans for the Gautrain expansion or a new school being built in your community – that's the power you gain by mastering this topic.

Lesson notes

2.1 Understanding Sections and Elevations Section: A section drawing is like slicing through the building vertically to reveal its internal structure. It shows the relationship between different floors, the height of the walls, the construction of the roof, the foundation details, and internal features like staircases. Think of it as looking inside the building if you cut it with a giant knife. Section drawings are essential for understanding the vertical dimensions and internal composition of a building. Important details displayed are wall types, floor levels, ceiling heights, roof pitch, and foundation depths.

Example: Imagine a section through a house showing the foundation, the brick wall construction, the window sill detail, the ceiling joists, and the roof rafters. This section allows you to see the layers of materials and how they connect.

Elevation: An elevation drawing is a view of the building from the outside, showing its external appearance. It shows the height and width of the building, the location of windows and doors, the roofline, and any exterior features like balconies or verandas. Elevations are usually drawn for each side of the building (front, back, left, and right). Elevations allow you to visualize the architectural style and proportions of the building.

Example: An elevation of a house might show the front door, windows, the roof overhang, and the exterior cladding (e.g., brick, plaster). The elevation doesn't show the inside of the house but gives you a sense of its facade. 2.2 Common Symbols and Abbreviations Doors and Windows: Building plans use standardized symbols to represent doors and windows. A door is typically represented by an arc showing the swing direction. Windows are usually represented by a series of parallel lines within the wall outline. There are variations in these symbols, but they generally follow these conventions.

Materials: Specific hatch patterns or abbreviations indicate different materials. For example, brickwork might be represented by a pattern of diagonal lines, while concrete might be represented by a pattern of dots and dashes. Abbreviations like "BRK" for brick, "CONC" for concrete, and "GALV" for galvanized steel are commonly used. A legend is vital for explaining what each symbol/hatch means on the plan.

Electrical and Plumbing: Electrical outlets, lights, and plumbing fixtures are also represented by symbols. 2.3 Line Types and Their Significance Visible Lines (Solid Thick Lines): These lines represent the visible edges of the building elements. They are the most prominent lines on the drawing.

Hidden Lines (Dashed Lines): These lines represent edges that are hidden from view. For example, the edge of a footing below ground level or a structural beam behind a wall. Center Lines (Long Dash, Short Dash): These lines indicate the center of a symmetrical object or feature, like a column or a doorway.

Dimension Lines (Thin Lines with Arrows): These lines show the extent of a dimension. The dimension is usually written above the line. Cutting Plane Lines (Thick Lines with Arrows): These lines indicate where a section has been cut through the building. The arrows point in the direction of view. 2.4 Dimensions and Scales Building plans are drawn to scale, which means that a specific distance on the drawing represents a larger distance in reality.

Common scales include 1:50 (1cm on the drawing equals 50cm in reality), 1:100, and 1:

2

0

0. It is crucial to check the scale on the drawing before taking any measurements. Dimensions are typically given in millimeters (mm) or meters (m). Understanding how to convert between these units is important. (1 meter = 1000 millimeters).