Professional Development – Blueprint Reading: An Art Unto Itself
My high school physics teacher used to say, the language of science is mathematics. Since I never spoke that language too well, I wasn’t much of a scientist. I’ve been an effective designer, though, and have learned the language of construction: “blueprint drawings”. Back in the day when I began learning to read plans, they were really “blueprints”, on blue paper, hence the term blueprint.
We communicate in job trailers by pointing to the significant sections of drawings. We make sketches, often quite rough, to show what we’re trying to say. In short, if you want to advance in construction, learn to read drawings well and to make rough sketches. It’s a simple language to learn, but it does take some studying.
So, how do you learn to read blueprints? It’s a little like eating an elephant. You might ask, “How do I eat an elephant?” The answer, of course, is “One bite at a time.”
Novice blueprint readers look at the entire page of words, lines and weird symbols and get overwhelmed. It’s easy at that point for your brain to shut down and you just say, “I can’t read blueprints.” If you tried to read an entire page of words at the same time, you couldn’t do that either. You simply have to calm down, start at one corner and begin figuring out what you can learn from the blueprint. The main difference between a blueprint and a page of text is that you know to start at the top left corner on a page of text, then to left to right till the bottom of the page. Blueprints don’t have a place you need to start. So where should you start?
Think: Plan – Elevation – Section
The most basic concept about reading blueprints, is “Plan, Elevation and Section”. Your first thought when looking at a drawing should be, “Is this a Plan, an Elevation or a Section?”
First, some quick definitions:
- Plan View: A view looking downward on the building, usually the floor plan from above.
- Elevation: A view looking sideways at the building, from the north, the west, the south or the east.
- Section: A cut-through view of the building, usually a view that shows how something will be built.
The rest of the information below will help you understand some other specific aspects of understanding blueprints. The most important thing to remember, though, is just to do one thing at a time. Don’t try to understand everything at once, no one can do that, so you won’t be able to either. Take some time, relax, look at each symbol and word and try to understand what it’s there for. Most everything on a blueprint is there for a purpose, so just slowly go through the symbols and words, getting their purpose into your head.
When printing hard copies, I often go through a new set of blueprints on a project with a yellow highlighter. I read and highlight every word, number or symbol. When I’ve highlighted an entire sheet, I’ve got a fairly clear idea of what the designer and draftsman were trying to convey. Today, Adobe can do the exact same thing digitally (As can other programs).
What is an Architectural Scale?
We use an Architect’s Scale when dimensions or measurements are to be expressed in feet and inches. Plans or blueprints always have a scale. Gradations on an Architect’s Scale are regular inch scale with gradations to the 16th of an inch.
What is an Engineering Scale?
We use an Engineer’s Scale whenever dimensions are in feet and decimal parts of a foot, or when the scale ratio is a multiple of 10. So an Engineer’s Scale has an inch broken into 10, 20, 30, 40, 50 and 60 gradations.
What Specs Should be Read?
The most boring part of learning to read blueprints may be reading Specs and General Conditions. So lots of folks just don’t do it. They make that decision lightly, but the ramifications can be huge. Most times the “Specs” are merely boilerplate added to the set of drawings to look official. But, many times Design Professionals hide little time-bombs in the Specs, or Special Conditions, that become important as the project progresses.
Perhaps it’s a milestone in the schedule that must be achieved by a certain date. Or a requirement to never work before 8am in the morning or on weekends. Sometimes the project clean-up requirements can be quite different from what might make sense to you, but those are the rules for that project.
So at the start of a project, the Construction Supervisor should obtain his or her own copy of all the project documents and read them. After doing this on a couple of projects, you will learn what you can skim through and what needs more careful attention. Don’t just blow off this duty, though.
The Project Specifications, General Conditions, Special Conditions and Construction Contracts constitute the rules for the project. It’s easier to win the game when you know the rules.
There are many different types of plans which can be separate, specific drawings or drawings incorporated into one large set. We will talk about the 3 types mentioned above.
Most construction drawings consist of orthographic views. A plan view is a view of an object or area as it would appear if projected onto a horizontal plane passed through or held above the object area. The most common construction plans are plot plans (also called site plans), foundation plans, floor plans, and framing plans. A plot plan shows the contours, boundaries, roads, utilities, trees, structures, and other significant physical features about structures on their sites. A foundation plan is a plan view of a structure projected on an imaginary horizontal plane passing through at the level of the tops of the foundations. Framing plans show the dimension numbers and arrangement of structural members in wood-frame construction. A wall framing plan provides information for the studs, corner posts, bracing, sills, plates, and other structural members in the walls. A roof framing plan gives similar information with regard to the trusses and other structural members in the roof. A utility plan is a floor plan that shows the layout of heating, electrical, plumbing, or other utility systems. Utility plans are used primarily by the sub-contractors responsible for the utilities, and are equally important to the builder. Most utility installations require that openings be left in walls, floors, and roofs for the admission or installation of utility features.
Elevation views show the front, rear, and sides of a structure projected on vertical planes parallel to the planes of the sides. Elevations give you a number of important vertical dimensions, such as the perpendicular distance from the finish floor to the top of the roof plate and from the finish floor to the tops of door and window finished openings. They also show the locations and characters of doors and windows. However, the dimensions of window sashes and dimensions and character of lintels are usually set forth in a window schedule. Typically, the elevation is what the homeowner is purchasing. When there is a discrepancy, it is usually best to match the elevation.
Section views are a view of a cross-section. The term is confined to views of cross sections cut by vertical planes. A floor plan or foundation plan, is a section as well as a plan view, but it is seldom called a section. The most important sections are the wall sections. Starting at the bottom, you learn that the footing will be concrete with dimensions and material details. The exterior wall section will show dimensions and materials to be used. This section will also show the details of the second floor, if any, showing if joists or trusses are to be used, again with dimensions and materials. The roof section will show any ceiling breaks, attic spaces, A/C spaces, etc. A roof framing plan (not really a section, but should be included here), will show the architects idea of what the truss layout should be. Beware: Sometimes the wall sections are from a generic page and do not relate to the specific project!
Detail drawings are on a larger scale than general drawings. They show features not appearing at all, or appearing on too small a scale, in general drawings. The wall sections are details as well as sections, since they are drawn on a considerably larger scale than the plans and elevations. Framing details at doors, windows, and cornices, which are the most common types of details, are nearly always shown in sections. Details are included whenever the information given in the plans, elevations, and wall sections is not sufficiently “detailed” to guide the craftsmen on the job.
The construction drawings contain as much information about a structure as can be presented graphically. A lot of information can be presented this way, but there is more information that the construction craftsman must have that is not adaptable to the graphic form of presentation. Information of this kind includes quality criteria for materials, specified standards of workmanship, prescribed construction methods, and so on. When there is a discrepancy between the drawings and the specifications, always use the specifications as authority. This kind of information is presented in a list of written specifications, familiarly known as the specs.
I’ve explained, as experience has taught me, the art of blueprint reading. The journey to understanding is not easy and only through continued use and education will you be successful. There are many sites online for good tutorials. Try it on for size. Click here for one that may help you. Remember, the industry is changing and we need to change with it!
Richard Gould – Design Administration
Gould Design, Inc.