PRP: Article - From Hand Drawings, CAD and now BIM

Architects, engineers, owners, contractors and building product manufacturers have been part of an amazing, and rapid transformation in how we communicate our building designs. We have gone from hand drawing, to CAD, to BIM is less than 25 years. This transformation has resulted in opinions as to which is best, fastest, results in the best designs and what should be taught in school. This article will provides an overview on each of these drawing approaches.

I. Hand Drawings

The first phase, hand drawing, has lasted for thousands of years. Over all those years, a consistency developed in the way contract documents are laid out, graphic standards used, and drawing sets organized. Interestingly, this consistency is an international language for drawings. In viewing drawings from many different countries, although the languages are different, the drawings are very consistent. And, one could easily conclude how a building was going to be built and how it would look. This consistence in contract documents has been a long process of trial and error, aiming for perfection, of the best way to communicate the designer's intentions to the builders.

Well done hand contract documents are beautiful; often they could be framed and displayed as art. The creation process was not so beautiful. Some designers spend some days erasing more than drawing. Every time a change is made to a plan it means days of changes to background drawings for reflected ceiling plans, electrical, mechanical, structural, plumbing and details drawings. The chances for errors and omissions were tremendous. There is little doubt that an experienced architect could find an error or omission in a set of hand drawn drawings in a couple of minutes.

Hand drawing also refers to renderings, sketches and thumbnail drawings. Once again, these can be works of art. At the thumbnail and sketch level, they capture the essence of the architect's concepts. The renderings tend to reflect the details of the design fairly early in the design phase. Architects use renderings to study design and having these rendering skills are tremendous. Unfortunately, many excellent architects are not great at renderings. There is a particular school that has applicants create a rendering of a campus building for admission. While this is an important skill, it is not necessary to be a great architect. Most of the spectacular renderings you have seen have been prepared by professional renderers (artists).

Hand Drawing Recap


Beautiful drawings
Time consuming
Prone to errors and omissions

II. CAD

CAD has only been around a few years, but has been an important advancement. It will be replaced, but has been an important transition to the more powerful future. CAD taught designers about computers, file management, and new organizational skills. CAD has been an amazing event. Instead of drawing on paper, you draw on a computer and see your work on the monitor. Fundamentally, CAD replaced hand drawing but did not substantially change the process or the way the information was displayed. A page of drawings was replaced with a drawing file, 100 sheets of paper are now (with some exceptions) 100 CAD files. Instead of spending days or weeks creating background drawings, they were ready instantly. Unfortunately, if you changed the base drawing, you still needed to swap out the old backgrounds for the new. Errors and omissions were not eliminated, but they were reduced. For example, dimensions were accurate. CAD based contract documents can be created much faster than hand created drawings.

You rarely hear of a CAD drawing referred to as beautiful or a work of art. In fact, in the first few years of CAD (1980-90), the drawings were terrible; no line weights, and only a couple of fonts.

CAD started as 2D only, but has now progressed to 3D. To date, it has not progressed to the level that it is practical to try to create a complete project in one 3D file. Certainly, for a quick glance at how the project will look, the 3D views are very good. And, as a background for creating hand renderings, it is a real time saver over the mechanical creation of the geometry.

CAD, linked to analysis, has been one of the most powerful reasons for using CAD. Analysis programs (structural, HVAC, electrical, energy) can extract data from the CAD file, run the analysis program, feed the information back to the CAD file and update the drawings (or even create new drawings automatically).

There has been criticism that CAD creates poor design. While I agree with many criticisms of CAD, I do not agree that CAD leads to poor design. For example, you can not tell a architect's experience when they show you a CAD drawing (or if they even created the drawing, compared to hand drawings where you could look at the drawing and make a very accurate evaluation of the architect's experience and abilities). Good designers look carefully at what they are designing, view the design from as many locations as necessary, and refine the design based upon the views (as well as the budget, program, site, etc.). Poor designers may be helped by CAD, as it is easier to see what they are proposing. An individual that is not a designer can use CAD to perhaps convince a customer that they have created a good design. The results of this individual's work will be the same, CAD or hand drawn.

CAD Recap


Faster than hand drawing
Less errors and omissions
Large, talented work pool