Lesson Notes By Weeks and Term v5 - Grade 11
Working drawings, detailing and interpretation of building plans – Week 8 focus
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Working drawings, detailing and interpretation of building plans – Week 8 focus
Download the Lessonotes Mobile South Africa app for faster lesson access on Android and iPhone.
Subject: Civil Technology
Class: Grade 11
Term: Term 4
Week: 8
Theme: General lesson support
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Working drawings are the language of construction. They're the detailed blueprints that builders use to turn an architect's vision into a real, tangible structure. Understanding these drawings is crucial not only for future civil technologists and engineers, but also for anyone involved in the building industry, including project managers, quantity surveyors, and even homeowners planning renovations. In South Africa, where infrastructure development and housing initiatives are ongoing priorities, the ability to accurately interpret building plans is a valuable skill, leading to better project execution, cost control, and safer construction practices.
2. 1.
Types of Lines and Their Meanings: Working drawings use different types of lines to convey specific information. Understanding these line types is fundamental.
Outline/Visible Line (Thick Continuous): Represents the visible edges of the building or component. It's a thick, solid line.
Hidden Line (Dashed): Represents edges that are hidden from view in that particular drawing. Centre Line (Long Dash, Short Dash): Indicates the centre of symmetrical features like columns, circles (e.g., indicating a drainage point), or the centreline of a wall. Dimension Line (Thin Continuous with Arrows): Shows the dimension of a feature. Terminates with arrowheads at the extension lines. The dimension value is placed above or within the line.
Extension Line (Thin Continuous): Extends from the object to the dimension line. Cutting Plane Line (Thick Chain with Arrows): Indicates where a section has been cut through the building. The arrows point in the direction of viewing the section.
Break Line (Zigzag or Jagged): Used to shorten a long object or feature that doesn't need to be fully shown.
Example: Imagine a plan view of a brick wall with a window opening. The outline of the wall and the window opening would be shown with thick continuous lines. If there's a lintel beam above the window that's not directly visible in the plan, its edges would be represented by hidden lines. A dimension line would show the width of the wall or the size of the window opening. 2.
2. Scales and Their Importance: Scales represent the ratio between the size of the drawing and the actual size of the building. Common scales for building plans include 1:50, 1:100, and 1:200. 1:50: 1 unit on the drawing represents 50 units in real life. (e.g., 1 cm on the drawing = 50 cm or 0.5 m in reality). This scale is used for detailed drawings. 1:100: 1 unit on the drawing represents 100 units in real life. (e.g., 1 cm on the drawing = 100 cm or 1 m in reality). This is a common scale for general floor plans. 1:200: 1 unit on the drawing represents 200 units in real life. (e.g., 1 cm on the drawing = 200 cm or 2 m in reality). Suitable for site plans and smaller building plans.
Calculating Real-Life Dimensions: To find the real-life dimension, measure the dimension on the drawing and multiply it by the scale factor.
Example: A wall measures 5 cm on a drawing with a scale of 1:
1
0
0. What is the real-life length of the wall? Real-life length = Drawing length x Scale factor Real-life length = 5 cm x 100 Real-life length = 500 cm = 5 meters 2.
3. Symbols and Abbreviations: Building plans use standardized symbols and abbreviations to represent different materials and components.
Common examples include: Door: A curved line swing showing the direction the door opens.
Window: Two or three parallel lines representing the glazing. WC: Water Closet (Toilet)
Basin: Washbasin/Sink Hob: A cooking stove top.
Refrig: Refrigerator Brk: Brickwork Conc: Concrete Steel: Steel South African Context: Pay attention to symbols specific to South African building practices, such as those for electrical installations conforming to SANS standards or specific roofing material types common in the region. 2.
4. Different Views: Plan, Elevation, Section: Plan View: A horizontal cut through the building, showing the layout of rooms, walls, doors, windows, and fixtures. It's like looking at the building from above. It shows dimensions of lengths and widths.
Elevation View: A view of the building from the outside, showing the facade and its features (e.g., windows, doors, roof lines, external finishes). It shows the heights of the building elements.
Section View: A vertical cut through the building, showing the internal construction details (e.g., wall structure, floor levels, roof construction, foundation details). Cutting plane line indicates the location of section cuts. 2.
5. Detailing of Building Elements: Walls: Drawings show the wall thickness, material (brick, concrete block, etc.), and any insulation or finishes. Details might include the number of bricks courses, plaster thickness.
Foundations: Drawings illustrate the type of foundation (strip footing, raft foundation), its depth, width, and reinforcement details. In South Africa, the type of soil dictates the type of foundation required and this information is often presented within the working drawings.
Doors and Windows: Drawings specify the door/window size, type (e.g., sliding, casement), and material. Door schedules are often included to provide a more comprehensive overview of all doors and windows.
Roofs: Drawings depict the roof shape (pitched, flat), material (tiles, corrugated iron), and structural support (trusses, rafters). Guided Practice (With Solutions)
Question 1: A line on a drawing measures 25mm and represents a wall.
The scale of the drawing is 1:
5
0. What is the actual length of the wall in meters?