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How to Read Blueprints: Complete Guide

blueprints Jul 15, 2020

Construction blueprints are technical drawings created by architects, engineers, and designers to put all the construction specifics of a house in one package to which the builder can refer as they construct the house. Although a package of blueprints can be daunting, as many as 50 pages long, the concept of the blueprint is simple: It is a series of two-dimensional representations of a three-dimensional building.

Professional builder and craftsman Jordan Smith explains in his class on reading blueprints

“A blueprint is the fundamental plan for the construction of any structure. The print is what shows the builders, the electricians, the framers -  all of the trades people exactly what needs done on any construction project.”

The main sections of a blueprint are: 

  • Title Sheets and Site Plans
  • Floor Plans
  • Elevations and Sections
  • Details and Schedules
  • Structural Drawings
  • Mechanical, Electrical, and Plumbing (MEP) Drawings

Each of these sections uses symbols, scale, and abbreviation to simplify reading the many elements that each plan contains. When you are able to read a blueprint all the way through, you will get a comprehensive understanding of its dimensions, building materials, installation methods, and the mechanical inner workings of the house, such as electrical and plumbing

Blueprints also contain details such as quality specifications, building codes, the information necessary for obtaining building permits, and even the schedule for accomplishing all aspects of the building. 

The ability to read and understand blueprints in an essential skill for those working in the building trades. Learn everything you need to know about reading blueprints in MT Copeland’s online class, taught by professional builder and craftsman Jordan Smith.

What kinds of drawings does a set of blueprints include?

There are many types of drawings that are used during the building process: architectural, structural, and mechanical. Some are used at specific stages, and others may evolve over time. These are the types of plans that should be included in a set of blueprints:

Architectural drawings

Architectural drawings will reflect the overall appearance—internal and external—of the home, how it is oriented on a building site, and the layout of its living areas

 

Site plan 

The site plan functions as a readable map of a building site, giving you the details you need to know about how the structure will be oriented on the lot. An architect or general contractor will create a diagram that shows the plot of land and its property lines, along with its landscape features, structural elements, setbacks, driveways, utility poles and power lines, fencing, and on-site structures.

 

Floor plans 

Imagine a view of a home sliced horizontally about five feet from the ground and looking down from above. This is the way a floor plan is drawn, and it is designed to give you a detailed idea of the layout of each floor of the house. It includes features such as walls, doors, windows, and even furniture.

Reflected ceiling plan (RCP) 

The RCP is a print that shows you the dimensions, materials, and other key information about the ceiling of each of the rooms represented on your blueprint. It takes its name from the idea that you are looking down at the ceiling as though there were a mirror on the floor reflecting the ceiling’s plan back to you. (Note that this type of drawing isn’t always included in the blueprints package.)

Detail drawings 

Special details of a house are included in drawings whose features are magnified so that a builder can see how to construct these elements. Structural connections, window openings, and wall junctions can all be included in supplemental detail drawings.

Elevations and sections 

Elevations show the vertical layout of the building, and there is usually one elevation drawing for each face of the building. An exterior elevation shows you what a house like if you’re standing front, next to, or behind it. An interior elevation shows the same thing, only from inside the house. Section drawings show what the building would look if you were to make a vertical cut through a particular part of a building to show a cross section of the structure, and how the spaces inside fit together vertically.

 

Structural drawings

Once the architectural drawings are complete, the architect sends those prints to an engineer, who uses them to create the structural prints. The structural drawings show how the house will be framed, and how the building will be given its structure. They are shown from the ground up; in other words; you’ll see a structural drawing for each floor of the house. As Jordan Smith puts it: 

“The architectural prints show how the building is supposed to look, how it’s supposed to interact with the humans that are living in it… However, it doesn’t give you any information on how to build it in such a way that it doesn’t fall down. The structural prints get into all of that detail.” 

The structural prints are sent back to the architect for review, and the team signs off on them before they’re included in the package and sent to the builder.

MEP (Mechanical, Electrical, Plumbing)  

Think of MEP as the central nervous system of a building, since every mechanical function that occurs in a building, from ensuring its air quality to planning its electronic and communications systems, to laying out complex piping routes, is performed by an MEP engineer. The MEP systems are usually delivered in a bundle as separate drawings. As a builder, it’s important to know where those systems will be routed, so you can leave space for them to be laid in. 

Mechanical 

The mechanical plans show the heating, ventilation, and air conditioning (or HVAC) systems of a building. These are all elements you will find in mechanical drawings.

  • HVAC systems
  • Exhaust systems
  • Direct digital control (DDC) systems
  • Chilled water systems
  • Heating water systems
  • Infection control HVAC

Electrical 

The electrical plans show how the electrical system will provide the power supply for lights and appliances. Electrical engineers design the best routes for wiring and design systems that can be safely and continuously operated. Some of the components of electrical plans include:  

  • Onsite power generation requirements and distribution
  • Information technology (IT) and audiovisual (AV) plans
  • Lighting and fire protection systems
  • Standby power systems

Plumbing

Plumbing designs reflect the complex piping and sewage routes for the building, as well as heated water and rainwater collection and storage. More and more, plumbing designers are called to develop efficient systems that can help decrease a building’s water consumption and reduce water bills. For instance, they plan low-flow fixtures in bathrooms, insulate piping and use alternative water sources. Some of the plumbing systems in MEP drawings include:

  • Natural gas piping
  • Domestic warm and cold water
  • Acid waste piping
  • Storm drainage systems
  • Vacuum/compressed air

How to read blueprints

First, understand that the entire package of drawings includes separate aspects of the construction that together reflect all the construction elements of the house. In order to get a complete picture of a house, start reading construction plans at the beginning, starting with the site plan. The plans give progressively more structural detail as you advance through the package.

Abbreviations and symbols 

The number of details that must be included in a complete set of blueprints is so large that architects reduce the information on the drawings to a set of standardized symbols and abbreviations in order to make the drawing easier to read and less cluttered. 

For reference, every set of architectural drawings includes a symbol legend. If you aren’t familiar with a symbol, you will be able to find it in the legend. Floor plan notes give additional context for the building. For instance, the notes can clarify exactly to what point on a wall dimensions should be measured.

Every symbol on the legend is drawn to the same scale as the rest of the floor plan. Most plans include symbols that are a combination of appearance (for instance, a bath looks like a bath); conventions (double lines are commonly used to denote walls); and labels (for instance, a thermostat is labeled “T”).  

Scale 

In order to fit all the information about a layer of a building onto a page, construction drawings and architectural drawings are drawn so that a small increment of measurement represents a larger increment. This means that the plans are drawn “to scale.”

Scales vary in complexity, from the simple (1 inch = 1 foot) to the complex (3/16 inch = 1 foot). The symbols are also drawn to scale so you will get an accurate idea of how elements of a room are configured in the space.

The scale is always shown on the same page as the drawing, either under the title or below an individual drawing. Keep in mind that scales can vary throughout a set of architectural prints, so check each page and use an architectural scale, or scaled ruler, to make sure you’re reading the print accurately. If you don’t own one already, it’s an essential tool of the trade for architects, engineers, and builders that you will want to buy now. You can also download a simple printable version from Archtoolbox.  

3 perspectives: plan, elevation, and sections 

A floorplan is the building plan that is most familiar to most people: a bird’s-eye view of a building with all the elements laid out on a horizontal plane. But in order to understand the structure in three dimensions, you’ll need to be able to read the plan, elevation, and sections together. For instance, while an elevation drawing will show what a house looks like if you’re standing next to its exterior or interior walls, the section view provides vital insight into how the construction will stand up. 

While elevations and sections are both vertical representations of a design concept, the section view reveals details of the construction of walls and the thickness and height of beams and other support. Working all together, these three types of drawings will give you the full picture of the structure of the house.

 

Schedules 

These documents show a listing of materials and products necessary for the structure, and the order of installation. Typical schedules include doors and windows and room finish schedules.

 

What is the relationship between blueprints and construction planning?

It’s important to understand who’s involved with the blueprints as the construction planning happens. In general, an architect will send the architectural drawings to an engineer, who plans the structural prints to work with the architectural plans. The structural prints are sent back to the architect to review. All parties should sign off before they are sent to the builder to execute.

 

MT Copeland offers video-based online classes that give you a foundation in construction fundamentals with real-world applications. Classes include professionally produced videos taught by practicing craftspeople, and supplementary downloads like quizzes, blueprints, and other materials to help you master the skills. 

 

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