How to read construction drawings correctly

If you intend to build a new family home or any other bulky structure, you definitely cannot do without construction drawings. Most general contractors get to know them at certain stages of construction work, and even demolition experts look at the blueprints to determine how to blow up the building.

Get to know the basics

Thanks to such construction drawings as blueprints, it is clear how the future house should be designed, what materials are needed for construction and where doors, windows, sinks and even household appliances will be located.

Architects, engineers and builders need to be able to read such drawings. Blueprints come in handy when making specific changes or renovating a building. They confirm that the current project has all the necessary permits for its construction and complies with all modern building regulations. Architectural design and construction workers will need the skills of correct and careful reading of construction drawings at almost every stage of their work.

In most cases, professionals draw blueprints to a 1/4 inch scale, meaning that each quarter inch on them will equal 1 foot of the actual length of the finished building structure. Be sure to familiarize yourself with basic terms and symbols before reading blueprints. Construction drawings can have different sizes, depending on the scope and the project's complexity. The regular blueprints for new home construction are 18x24 inches or 24x36 inches. 

Main photo by fanjianhuao on Freepik
Photo by Freepik


The main features of blueprints

In title blocks, you can usually see company logos, contact details, client names, architects' names, project names, site addresses, site locations, names and dates of drawings, number of sheets, current permits and scale of drawings. The title block can be rectangular or in the form of a narrow strip that covers the entire sheet. In any case, it contains primary data about the current project.

The next element is the revision block, where all changes made to the blueprints are noted. Such blocks are provided for many parts of the plan. During the first drawing of blueprints, the revision block is left empty, awaiting editing of constituent parts.

Also, just like a map, a blueprint has a grid system along the horizontal and vertical edges. You may see numbers on one axis and letters on the other axis, and this makes it easier to refer to a specific location on the drawing. Another essential thing is notes and legends, usually placed at the bottom of the plans and the keys to deciphering the symbol abbreviations on all parts of the drawings.

The last key element is the drawing or plan. This area is located in the center of the blueprints sheets and illustrates a specific look, feature or system of a particular project.

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Four general perspectives in construction drawings

Thanks to the construction drawings, we can see the view of the project from different angles. It can be not only a floor plan but also images that show the project from the following perspective: 

• Plan view provides architects and builders with a bird's-eye view of a new project. In this case, each of the floors of the building is depicted separately.

• Instead, elevation drawings help to imagine what the final appearance of the building will be from the front, sides, or back. Such graphics can show both the interior and the exterior. They are sometimes published in the media to give the public an idea of ​​future shopping centers or educational institutions.

• Cross-section drawings are drawings of the finished building as if it were cut vertically. They clearly show ​​floor heights, rafter lengths, staircase designs, etc. Such drawings are necessary for a building's framing plan. They also help to understand whether beams, joists and columns fit well together.

• The fourth type of drawing isometric drawing, a three-dimensional image in which lines are drawn at an angle of 30 degrees. It shows various internal features, including the design of the premises.

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What do the blueprint lines mean?

If you intend quickly learn and understand construction drawings, you need to familiarize yourself with their line types. Lines can represent a wall, appliance, size, range of motion, and more. They often have different thicknesses. That is, they are straight, curved, dotted or solid. We will consider them in more detail below. 

– object lines show the outer surface of each object that would be visible in the finished house. These are the thickest lines on the blueprints. Hidden lines show those surfaces that would not be visible to the human eye in a ready house because they are on the back of a specific object. You can find many such lines in isometric drawings.

– dimension lines have arrows that indicate, for example, the distance between walls or wires in an outlet. Center lines indicate the central axes of symmetric objects, and phantom lines show variants of the positions of moving objects. As for extension lines, these are auxiliary lines, sometimes indicating the outer limits of dimension lines.

– leader lines and arrows that emphasize specific nuances of the drawings that require additional explanations. And break lines allow drawing authors to reduce the size of depicted objects. 

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Here are a few tips for reading drawings easily

If you are new to reading construction drawings, you should familiarize yourself with the title and legend. You'll come back to it many times throughout the project, but by introducing yourself to the key symbols beforehand, you'll have a basic understanding of the drawings.

It is also vital to understand what plans you are looking at and what you will need for each project. Each project will be unique, so learning how to read and understand the plans is essential. You will need to decide which elements of a particular project are the first in the process of its implementation. Any trivial mistakes can disrupt the project deadline or increase its cost.

Learn about everyone you'll be working with, from architects to electricians, and make sure they're all on the same page.

Drawings will always be a vital element of any construction project. They help specialists understand how a specific project will look after its implementation and reveal in detail how to get the expected result step by step. Thanks to blueprints, you can build a new family home or other building that will perfectly pass the test of time.

It is very important for owner to save the drawings after construction.

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