PlanGrid Construction Productivity Blog

The history of blueprints

Closely tied with the history of building is the development of standardization and reproduction of documents. How does a building go from a designer’s imagination to a three-dimensional reality? How does a complicated structure with so many parts, materials, and workers to coordinate get built to specification, and built to last? The answer is in the shared language of building — the architectural drawing.

Medieval Drawings

This drawing, known as the Plan of St. Gall, is one of the oldest known surviving architectural plans. It was drawn in the 9th century and is an imagination of an ideal monastery complex. It was drawn on five sheets of parchment sewn together in red, brown, and black ink with a scale of 1:192. Though the complex was never actually built in its time, it’s being rebuilt in Germany using period tools and techniques. It’s estimated the rebuilding will take 40 years. You can view a detailed diagram and models based on the plan here.

The Plan of St. Gall

Renaissance Drawings

Architect and engineer Filippo Brunelleschi was known to have used the camera obscura to copy architectural details from the classical ruins that inspired his work. The architects of the Renaissance period brought architectural drawing as we know it into existence, precisely and accurately reproducing the detail of a structure via the tools of scale and perspective.

Camera Obscura
U.S. Capitol Winning Design, 1796

Early Modern Drawings

Until the mid 19th century, architects relied on skilled draftsmen to faithfully copy their drawings for distribution. Myriad specialized instruments used for copying lines, curves, and arcs, from the french curve to the set square and the bow compass, were the tools of the draftsman’s trade.

Drafting tools
Draftsmen at work

How the Blueprint became Blue

In 1842 blueprints became blue when the cyanotype process was discovered by John Herschel. It was intended as a means of reproducing notes and drawings, but was quickly adopted by artists and scientists. It became a common way of preserving the silhouette of leaves, ferns, and other botanical samples. An architectural drawing was made on a semi-transparent paper, then weighted down on top of a sheet of paper or cloth that was coated with a photosensitive chemical mixture of potassium ferricyanide and ferric ammonium citrate. It was then exposed to light. The exposed parts of the drawing (the background) became blue, while the drawing lines blocked the coated paper from exposure and remained white.


Midcentury Drawings

While draftsmen were still employed to copy drawings into the modern period, a variety of chemical and mechanical processes were developed during the 19th and 20th centuries for reproducing architectural drawings. The diazo process replaced cyanotype as the dominant printing process for most of the 20th century. It produced a white print with blue lines, and was also known as a “blueline” drawing or “whiteprint”. Diazotypes used a similar chemical process to the cyanotype. A drawing was made on mylar or another translucent surface, placed on chemically coated paper, and exposed. The American Institute for Conservation lists 14 different types of processes for reproducing drawings they discovered while conserving the New York Botanical Garden Library’s collection of drawings:

  • Aniline prints
  • Cyanotypes
  • Diazotypes
  • Electrostatic prints
  • Ferrogallic prints
  • Gel-lithographs
  • Hectographs, (handmade)
  • Pellet prints
  • Photostats
  • Sepia prints
  • Silver halide prints
  • Stencil duplicating (mimeographs)
  • Spirit duplicating (hectographs, machine made)
  • Van Dyke prints
20th Century hand drawn plan

CAD Drawings

The end of the 20th century saw the development of computer aided drafting technology and large-format printing processes that made the reproduction of multiple accurate copies of the architect’s original design easier than ever. Along with the ability to print to paper with ease came a document management nightmare.

Paper plans organized by color


With PlanGrid’s cloud-based document control solution, digital drawing files are distributed instantaneously from office to the field. Project files are uploaded to the PlanGrid cloud once and synced to all the individual tablets of project collaborators. What used to take hours of project engineer’s time to manually unbind reams of blueprints, physically leaf-in revisions sheet by sheet is now accomplished by PlanGrid’s automatic version control. Chasing down foremen and superintendents to hand them a paper copy of the latest updates is rapidly becoming a thing of the past.

Blueprints on PlanGrid on a tablet in the field
Blueprints on PlanGrid in the job trailer