Lesson Notes By Weeks and Term v5 - Grade 11

Lesson Video

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Performance objectives

• Identify symbols and abbreviations according to SANS 10400.
• Interpret dimensions and scales to calculate real-world measurements.
• Describe the components and specifications of wall sections.
• Locate and describe specifications for doors and windows.
• Understand the layout of plumbing and electrical plans.

Lesson summary

Working drawings, detailing, and the interpretation of building plans are fundamental skills for anyone involved in the construction industry. This knowledge isn't just theoretical; it's practically applicable to numerous situations South African learners will encounter in their lives. For example, understanding building plans allows informed participation in community development projects, enables informed decision-making regarding home renovations or construction, and provides a pathway to various careers in the building industry (architectural draughtsperson, site foreman, construction manager, etc.).

Lesson notes

2.1 Understanding Working Drawings: Working drawings are a set of detailed drawings used by contractors and builders to construct a building. They are more comprehensive than architectural drawings used for visualization. They provide all the necessary information required to build the structure accurately and safely.

This includes: Site Plan: Shows the location of the building on the land, including boundaries, setbacks, contours, existing services (water, sewer, electricity), and any other relevant site features.

Floor Plans: Top-down view of each floor level, showing room layouts, dimensions, wall thicknesses, door and window locations, and fixtures.

Elevations: Orthographic projections showing the external appearance of the building from different sides (front, rear, left, right).

Sections: Vertical cut-through views of the building, showing the internal construction details of walls, floors, roofs, and foundations. Wall sections are particularly important for this week’s focus.

Details: Enlarged drawings of specific building elements, such as wall junctions, window frames, or staircases, showing precise dimensions and materials.

Schedules: Tables listing information about doors, windows, finishes, and other building components.

Services Plans: Drawings showing the layout of plumbing, electrical, and mechanical systems. 2.2 Standard Symbols and Abbreviations (SANS 10400): Understanding symbols and abbreviations is crucial for accurate plan interpretation. SANS 10400 outlines the standardized symbols used in South African building plans.

Common examples include: Door Swing: A curved line indicating the direction and radius of the door's swing.

Window: Represented by parallel lines within a wall, with variations indicating window type (e.g., sliding, casement). WC: Water Closet (toilet).

WHB: Wash Hand Basin.

DPC: Damp-Proof Course (a layer preventing rising damp). GL: Ground Level. FL: Floor Level. CL: Ceiling Level. Specific material symbols (e.g., concrete, brick, steel). These are often hatched differently to distinguish them. 2.3 Dimensions and Scales: All working drawings must be drawn to scale.

Common scales include 1:50, 1:100, 1:200, and 1:

5. The scale indicates the ratio between the drawing and the actual size of the building.

Example: A scale of 1:100 means that 1 unit (e.g., 1 cm) on the drawing represents 100 units (e.g., 100 cm or 1 meter) in reality.

To calculate the real-world dimension: Real-world dimension = Drawing dimension x Scale factor 2.4 Wall Sections – Focus on Components: Wall sections are extremely informative and detailed. They show how the wall is constructed from the foundation up to the roof.

Key components to identify include: Foundation: The base of the wall, transferring the building's load to the ground. Types include strip foundations, raft foundations, and pile foundations, depending on soil conditions. In South Africa, strip foundations are very common for single-story dwellings.

Footing: The widened base of the foundation, providing increased bearing area.

Foundation Wall: The section of the wall below ground level, usually made of concrete or brick.

Damp-Proof Course (DPC): A waterproof layer (usually made of bitumen or plastic) placed at least 150mm above ground level to prevent rising damp. This is vital in South African climates with high rainfall or humidity.

Wall Materials: Brick, concrete block, or timber frame walls. The type of material is indicated by hatching and symbols.

Wall Finishes: Plaster, paint, cladding, or other materials applied to the interior and exterior walls for aesthetic and protective purposes.

Lintels: Beams that support the wall above openings (doors and windows).

Cavity Walls: (If applicable) Walls consisting of two layers of masonry with a cavity in between, providing insulation and preventing moisture penetration.

Example 1: Calculating Real-World Dimensions from a Floor Plan: A floor plan is drawn to a scale of 1:

5

0. The length of a room on the plan measures 8cm. What is the actual length of the room? Scale factor = 50 Drawing dimension = 8cm Real-world dimension = 8cm x 50 = 400cm = 4 meters Example 2: Interpreting a Wall Section: A wall section shows a strip foundation with a footing of 600mm wide and 300mm deep. The foundation wall is made of concrete blocks and is 200mm thick. A DPC is shown 200mm above ground level. The wall above the DPC is made of clay bricks, 230mm thick, and finished with plaster on both sides.

Interpretation: The foundation is a standard strip foundation suitable for relatively stable soil. The DPC prevents rising damp, which is crucial for durability. The clay brick wall provides thermal mass, which can help regulate the internal temperature of the building, important in areas with hot summers and cold winters. The plaster provides a smooth surface for painting and further protection.

Example 3: Identifying Materials using Symbols A section of a drawing shows diagonal hatching.