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Reading Drawings


Basics of Drawings and Blueprints: Chapter 3


Reading Drawings


In this module, we will learn how to read drawings or blueprints. Skip to quiz!


Basics of Drawings


As we all know, various drawings are needed to describe a project accurately. Generally, there are two main types of drawings, architectural and engineering drawings. In addition to these two categories of drawings, other drawings are provided for more details.


For example, a concrete wall may be described as its size and finish on the architectural drawings. Still, an engineering drawing is also needed to spell out the exact structural components, such as the spacing and size of steel reinforcing in the wall.


An architectural floor plan might show exact information about rooms, doors, windows, and other particulars. Items such as the exact placement of office desks and files are provided in a separate furniture installation plan. We will discuss the basics of drawings that apply to all the drawings.


Notes are used on construction drawings to identify features or information that plans or symbols cannot convey. Notes are concise, easy to read, and clear in their meaning. Notes as placed close to the elements described to keep leaders as short and direct as possible.


Leaders are drawn from the beginning of the note and generally end in an arrow pointing to the object. The size of sheets that drawings are drawn can vary among professional firms, depending upon office standards and the type of project.


The most common sheet sizes used by offices are:

  • 18 x 24 inches (457 x 609 mm),

  • 24 x 36 inches (609 x 914 mm), and

  • 36 x 48 inches (914 x 1218 mm).

Small drawings, such as revisions or additions to a large drawing, are typically drawn on 8 1⁄2 x 11 inches (213 x 275 mm).


Standard paper sizes include A, B, C, D, and E with inches in architectural sizes. Metric sizes are measured in millimeters and include A4, A3, A2, A1, and A0. Refer to the table for architectural sizes.


The title block consists of details of respective drawings. t is provided at the bottom or right side of the sheet when viewed horizontally, but never at the top or left side of the sheet. The title block consists of drawing names, constructors, and dimensions.


Specifications are written documents that clearly describe the required materials, method of work, and workmanship. The specifications are placed directly in the drawings or a separate drawing sheet for large projects. However, for most projects, the specifications are included in a Spec book or Project manual.


It is issued with the contract agreements and construction drawings as the complete set of contract documents. Many architects and interior designers use the Contract Specifications Institute (CSI) developed specification system, known as the master format system.


There are many types of lines used in drawings, but each line type has its representation. In drafting, continuous lines of various weights represent objects and significant elements such as structural walls and columns. Dotted lines usually denote objects hidden from view.


The following are the most commonly used line types:

  • Cutting lines: Show major parts in a building or object.

  • Object lines: show primary outlines of building elements or objects.

  • Hidden lines: indicate areas or objects not visible on the surface or objects hidden behind others.

  • Centerlines: locate the symmetrical center of objects such as doors, beams, and walls.

The line type used in the drawing is described on the same page or at the starting pages of the respective drawing set.


The sheet numbering system can vary according to the type of project and office preference. A simple numeric system is used for small projects, and other drawings have a prefix, such as A for the architecture or M for mechanical. The sequence is followed in the drawing set with respective prefixes.


A list of the most common prefixes as follows;

  • Title Sheet T-01

  • Architectural Drawings A-01

  • Structural Drawings S-01

  • Plumbing Drawings P-01

  • HVAC Drawings M-01

  • Electrical Drawings E-01

However, other prefixes may be added as needed by the office.


The drawing stages involved in any project are:

  • Pre-design,

  • Schematic design,

  • Design development,

  • Construction drawings, and

  • As-Built drawings.


As-Built drawings show all the major and minor modifications made by the contractor to the original or first set of the drawings. The preparation and use of as-built drawings come into play at the final phase of the project. It is also known as record drawings or red-line drawings.


As-Built drawings provide a detailed blueprint of the building and final construction with all the modifications. As-Built drawings are specially used at the time of renovation and maintenance purposes.



Understanding the Drawings


Title blocks on a construction drawing sheet serve several vital functions. Title blocks are standardized for each office and are generally placed along the right side of the sheet. It is the full height of that edge, leaving the page's top and bottom borders or margins.


Title blocks generally include:

  • Design firm’s name/logo, address, telephone/fax number, and e-mail address,

  • Contractor details,

  • Date,

  • Revision details,

  • Approval agency seal,

  • Sheet title, and

  • Sheet number.


Title blocks also include a space for the authority or person's initials who approves the drawing with its seal. The title block generally includes a revisions section to indicate changes made to the original drawing. When several revisions are made to a drawing sheet, they are listed under the revisions section.


The index sheet includes the sheet name and sheet number of drawings used to describe the project. The index also serves as a list of drawings so that if a drawing is missing, it can be identified from it. Sometimes revision is provided for limited drawings sheets, highlighted in the index sheet for better identification.


Schedules include manufacture name, type, model, size, and details of equipment. Schedules provide the details of the equipment or object denoted on the respective plan set. All drawings include schedules for equipment such as door, wall, furniture, ceiling, panels, fans, heaters, and chillers.


Abbreviations are shortened words or short phrases often used in construction drawings. Abbreviations can vary among the trades, and for example, QT means quarry tile or quart. The architect, engineer, interior designer, drafter, and contractor provide what each abbreviation stands for.


The drafter includes a legend of abbreviations to ensure what it is meant for in the drawing. Abbreviations differ from one drawing to another, and their details are provided on the first or general sheet of any drawing.


The construction drawings consist of graphical symbols with notes described in the legends. Legends are also available on floor plans, furniture plans, electrical, plumbing, and mechanical plans. For example, a wall legend designates a specific wall construction assembly on a floor plan.


There are many commonly recognized legends and graphic symbols that are widely used in drawings. Legends are concise, graphically represented, and also contain abbreviations of equipment. Legends are provided on the first page of the respective drawing set.


Graphic symbols are used in drawings as a pictorial shorthand to reduce drawing time and repeated descriptions of the same object. For example, symbols are used on an electrical floor plan drawing to indicate placement and type of electrical outlets and wall light switches.


Symbols may vary from office to office, but all architectural and interior design firms use standard symbols. Each symbol used in a plan is clearly defined in the schedules, legends, details, sections, or sometimes in the plan notes.


The basics for all the drawings are the same in both architectural and engineering drawings. The drawings consist of different sheet reference names and numbers to differentiate from another. The drawings consist of the title block, legends, abbreviations, symbols, and general notes used widely to refer to any drawing.


 

Question #1: In the drawings, object notes are described using:

  1. Arrow

  2. Table

  3. Notes

  4. Leaders

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Answer: Leaders

In the drawings, object notes are described using leaders.


Question #2: The most common sheet sizes used for drawings by the offices are: (Select all that apply)

  1. 18 x 24 inches

  2. 12 x 8 inches

  3. 36 x 48 inches

  4. 4 x 6 inches

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Answer: 18 x 24 inches

36 x 48 inches

The most common sheet sizes used for drawings by the offices are:

  • 18 x 24 inches (457 x 609 mm),

  • 24 x 36 inches (609 x 914 mm), and

  • 36 x 48 inches (914 x 1218 mm).


Question #3: In the drawings, _____ of various weights represent objects and significant elements such as structural walls and columns.

  1. Scale

  2. Lines

  3. Menu bar

  4. Leaders

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Answer: Lines

In the drawings, lines of various weights represent objects and significant elements such as structural walls and columns.


Question #4: A list of the most common prefixes used in the drawings sheet numbers are: (Select all that apply)

  1. DW-01

  2. A-01

  3. MEP-123

  4. T-01

Scroll down for the answer...


















Answer: A-01

T-01

A list of the most common prefixes used in drawing sheet numbers are;

  • Title Sheet T-01

  • Architectural Drawings A-01

  • Structural Drawings S-01

  • Plumbing Drawings P-01

  • HVAC Drawings M-01

  • Electrical Drawings E-01


Question #5: Which drawings are specially used at the time of renovation and maintenance purposes?

  1. Current drawings

  2. Floor plan

  3. As-Built drawings

  4. Construction drawings

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Answer: As-Built drawings

As-Built drawings are specially used at the time of renovation and maintenance purposes.


Question #6: Which sheet of the drawings also serves as a list of drawings?

  1. Index

  2. Legends

  3. Symbols

  4. Last

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Answer: Index

Index sheet also serves as a list of drawings so that if a drawing is missing, it can be identified from it.


Question #7: In the drawings, ______ includes manufacture name, type, model, size, and details of equipment.

  1. Abbreviations

  2. Schedules

  3. Section drawing

  4. Leaders

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Answer: Schedules

In the drawings, schedules include manufacture name, type, model, size, and details of equipment.


Question #8: The construction drawings consist of graphical symbols with notes that are described in:

  1. Symbols

  2. Table

  3. Schedules

  4. Legends

Scroll down for the answer...


















Answer: Legends

The construction drawings consist of graphical symbols with notes described in the legends.

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