Construction blueprint reading seems to be a lost skill. It is certainly an acquired skill.
I decided to write this in my Sedimentation and Erosion Control section because in my experience reading, understanding, and correctly building from blueprints is much more of a problem in civil construction than in the building trades in general and carpentry in particular.
I think that may be because people have lived and worked in buildings all their lives. They know what a wall or a floor is and where it belongs in a structure. If they go into a bathroom, any bathroom, they can identify the sink, the toilet, and the bathtub because they have used bathrooms all of their lives. People aren’t raised in sediment basins. If you show them a riser assembly without prior training or explanation they could only guess what part might be the trash rack, the anti-floatation or the skimmer.
So, some familiarity with the blueprint subject is necessary. Knowing or learning the definitions and functions of components or having reference to those definitions while reading plans is also important.
Much of plan reading is simply reading. In addition to the drawings and details, there are notes, legends, directions, and notification that may give an explanation to the drawings of may contain stand-alone information.
Construction Blueprint Reading-Pieces and Parts
The drawing legends will help understand what is drawn. The legend will give a side by side illustration and description of what each line and symbols represent.
Part of the site plan will be removing existing vegetation and re-establishing vegetation once construction is complete. In relation to these efforts notes on clearing and grubbing, erosion control notes, temporary seeding schedules, permanent seeding schedules and seedbed preparation will, likely, be contained in the blueprint.
Owner information, contractor information, designer information, property information, project information are all there for your reading pleasure, no diagram interpretation needed.
The erosion control plan, depending on its complexity, may be included on the site plan or it may have its own page or pages. The erosion plan or sediment and erosion control plan will show locations of silt fence, filter sock, check dams, sediment basins and related structures.
Both of these pages will have notes and reference to detailed drawings of a larger scale of important elements of the plan. These details may have their own notes giving further explanation. The written notes certainly help decipher the diagrams.
Construction Blueprint Reading-The Drawings
Drawings seem to be the scary and difficult part. I think many inexperienced plan readers just see a blur when they open a set of plans. They experience information overload. All anyone can do is absorb the information one page, one drawing at a time.
There will be an orientation arrow which may show repeatedly throughout the plan set. The arrow will indicate North.
Usually, a vicinity map shows the site in relation to the nearest road or roads.
A small scale, undetailed drawing is usually included showing the size and shape of the project.
A topographic map of the site will show dashed lines running up, down, and across the page. The more lines you see and the closer they are together the more grade is present on the site. Spaced every five to ten lines a line will be numbered with the elevation above sea level. Following these numbers will tell if the grade is getting higher or lower. This drawing may also contain the grading plan which will show how the designer wants the elevations changed by a grading operation. This information will be shown by a different type of line and be referred to as the grading plan.
The site plan will show roads, fences, structure location and may give property and owner location of adjacent parcels.
Construction Blueprint Reading – A Simple Way
I absorb the blueprint information by examining the sheets one at a time. Use a 24×36 inch (or larger) set of blueprints and a red pencil. Then go over each page drawing by drawing, detail by detail, and note by note. I start at the top center of each page and work my way clockwise around the page. I tick off each item that I feel I completely understand then circle items that I understand but the importance of which needs more review. Just as important, I add question marks to what I don’t understand or to what I feel is wrong.
This can be a time-consuming process but takes less time than dealing with construction mistakes due to lack of understanding or even reading the plans.
I’ll give one example.
Construction Blueprint Reading – What Can Go Wrong?
I was told that the five sediment basins on a particular site had been built and were ready for inspection. When I observed the first basin, I observed that no component of the basin was correct. The most glaring deviation from the plan was the depth of the floor. The basins were to be around four feet total depth. The first that I inspected was about twelve feet deep. The worst that I inspected was about 20 feet deep. I pointed out the errors. The foreman told me that he wasn’t, “too good with plans reading”. He understated that, to say the least. Those basins never worked properly. What the regulators thought about the construction at the final inspection I cannot say.
How do you learn? Dive right in and practice what I have preached here. Buy a book and do what it says step by step. If already doing construction ask to be included in plan reviews. Also, ask foremen or superintendents to share what they know about plan reading. In addition, more formal instruction can be had at some community colleges that offer construction management or carpentry courses.
So, the more you do it, the better you will be at it.
Here is a site that delves deeper into the mysteries of construction blueprint reading and could be of some help.
What have I missed? Feel free to comment.