I was recently struck by how the masonry trade is an extreme blend of old and new technology. I’ve just returned from a Mission trip to Malawi, a small country in South East Africa. One activity for our group was to install a new sheet metal roof on a home in a poor village. Roofs in this village were primarily constructed by lashing sticks together into a crude frame and then covering the frame with bundles of grass to provide minimal shelter from sun and rain. The homes were primarily constructed with mud brick. These bricks are dug from the native soil on site and then baked in a wood fired oven, also on site, to remove some of the moisture. The end product is a brick that is only slightly stronger than a dirt clod. They are laid in running bond using mud as mortar. They dig a small hole on the site and periodically wet the hole to dig “mortar” for laying the brick. No cement or other additive is used.
On one hand it seems like a very crude construction method compared to my experience with masonry in the US. Dimensional tolerance? Unit compressive strength? Type S or Type N? f”n? On the other hand it illustrated the simple beauty of masonry and the ancient roots of the trade. These structures were surprisingly sound. They have high thermal mass, are termite proof, require no transportation of materials, are 100% recyclable, are locally mined and manufactured. In fact they surpass even our best efforts at being “green” and sustainable. One man can mine, manufacture, deliver and install all the necessary components to build these structures. Pretty remarkable if you think about it.
It was an experience for me that highlighted the mix of old and new technology in the masonry trade. Since it’s inception thousands of years ago, masonry has in many ways not changed. It is still practiced today in exactly the same form that it began so long ago. Even in it’s most basic form it is still a very effective means of providing shelter and security for people all over the world. On the other end of the spectrum is my day to day experience with masonry in the US. My time is spent using high end computer hardware, the latest in software developments, intricate algorithms and analytical methods to develop 3D models of masonry buildings to advance the art of BIM for masonry. While it’s exciting to bring the newest technology to the masonry industry, it was refreshing to see first hand how enduring, efficient, and essential masonry building methods are to people around the world.
CAD BLOX was recently contracted to model a particularly challenging masonry layout for the Museum of Prairiefire in Overland Park, Kansas. Verner Johnson Inc. designed the building using a complex blend of stone veneer products that did not lend itself to standard BIM masonry modeling techniques. The intent was to create a gradient of color and texture moving vertically up the wall. To accomplish this effect over the 46′ high cavity wall, 32 separate horizontal zones were established each containing a unique mix of material, color and texture with variable blends. Five colors of Cordova Stone (formerly Prairie Stone) and four colors of natural limestone in two different textures were used to compose the blend with each band varying proportions of product. In addition to the variation of product and color, unit height varied and unit lengths were randomly mixed. As you can see from the model of one of two structures, the veneer envelope was also uniquely shaped. All these variables converged to present a very challenging modeling proposition.
Due to the number of variables and the desire for a random effect in the distribution of stone lengths, it was not realistic to create an exact stone model with individual unit placement. While it was possible to build such a model, the drawings and order produced by such a model would be far to constraining to use for construction. Instead, CAD BLOX opted to create a custom modeling approach that allowed for flexibility in the unit placement while preserving the accuracy of unit counts to produce an accurate order. This also allowed the mason, D&D Masonry, the freedom to blend the product in an efficient way with proper proportions for each band coming directly from the model. This hybrid modeling solution preserved the integrity of the order, was specific enough to yield useful data for each band, yet freed the mason to practice their craft in a cost effective manner.
The other interesting aspect of this project was the timing of CAD BLOX’s involvement. CAD BLOX was contracted prior to bid which allowed for an accurate bidding process as well as early interaction with the architect to manage the complexity of the design from the standpoint of cost. The ability to have an accurate picture of cost as well as a basic strategy for construction provided very useful feedback for budgeting and the impact of design changes to the stone. The information generated from the model provided a basis for controlling costs by adapting the masonry materials and layout while still preserving the design intent. The Museum of Prairiefire illustrates how the use of BIM masonry modeling techniques can help preserve a complex masonry design through the bidding and construction process to make creative designs affordable and buildable realities.