Archive for August, 2019

Building Design For Printability

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By Mark Lundegren

DSC_0661-Edit~2

Architects, builders, planners, and developers are doubtless aware that 3D printed buildings and larger communities are on the horizon, with early prototypes now in the popular and professional press. In this approach, large three-axis printers, or alternatives such as ones pivoting from a central point, are used to place materials in a specific order via design and printing software.

While this potential is well-recognized, at least three important aspects of this likely change in construction methods may be overlooked. First is that it will both require and strongly incentivize new Design for Printibality (DFP) standards and practices. On one hand, this will be necessary to enable reliable use of the technology, and also encouraged by the fact that machine-printed buildings with high DFP quotients – from backyard sheds to urban skyscrapers – may become substantially less expensive to construct and maintain than traditionally-built ones.

To Sense Potential Changes, Consider Which Form Is Easier to 3D Print

Second, as my intentionally provocative photo suggests, perhaps few of us have considered how radically DFP may alter building design and engineering, and the typical building shapes and fine-scale design features that we typically employ and take as given today. But to quickly understand this prospect, consider that much of human architecture, historically and in our time, has a low DFP quotient and is likely to be strongly disfavored or disincentivized by 3D technology.

Third, perhaps just as few of us are aware that DFP standards exist already, owing to the rise of desktop and industrial 3D printing, that these standards appear broadly applicable to building design at all scales, and also that they likely offer a significant window onto future building design and construction.

I would like to briefly summarize key DFP principles from desktop and industrial printing, and then discuss their implications for building design and construction in a 3D-printed era. But let me first offer a quick acid test of building and structural design printability up-front. Simply put, if you can’t print a design model on a desktop 3D printer, it is unlikely to be printable at full-scale – though there may be exceptions to this rule, some of which we will discuss.

3D PRINTING OVERVIEW

As outlined, the primary technology of 3D printing in our time involves either X-Y-Z or pivoting printers, along with their enabling software. Together, they allow us to render computer generated images in plastic or some other extruded or sprayed, quickly-solidifying, and usually self-binding material. Typically, objects are printed in small layers or planes, one upon the other, in a process known as fused deposition. And already, 3D printers can produce a variety of items – from gears and art to toys and teeth.

Example of Industrial 3D Printer In Action

Importantly, other 3D printing technologies are possible and indeed seem inevitable in building construction. A good example of this, in use today, is the 3D etching of silicon chips and other materials. But even here, subsequent depositional layering and fusing is employed to place new materials within or above etched areas. Similarly, 3D milling technology is now in increasing use, where the printing nozzle of a 3D printer is replaced with a spinning drill or high-energy laser, and used to sculpt objects from larger blocks of material.

Since it appears that future 3D printed building technology will primarily, or at least initially, involve fused deposition techniques, perhaps with robotic insertion of modular elements – from rebar and lintels to floors and conduit – my comments regarding DFP will primarily focus on depositional methods. In any case, they come with the understanding that new printing techniques naturally will come with their own DFP demands and opportunities, some specific to the technique and others more general or broadly applicable to mechanical printing in all its forms.

Looking at the literature on artisanal and industrial depositional printing (example 1, example 2, example 3), a number of core DFP principles quickly emerge. Notably, all are fairly intuitive, nearly all center on resisting or working with gravity during and after the printing process, and most appear to have direct corollaries in the architecture of natural geological deposition. These DFP principles include:

> Selecting materials for adequate strength, endurance & other qualities

> Establishing an adequate base or foundation for the object

> Limiting the depositional incline or cantilever of materials

> Avoiding large unsupported prominences and flat spans

> Use of temporary printed buttresses to support materials while solidifying

> Inclusion of curves, ribs, and articulation to increase final object strength

You probably can see that this list of DFP considerations is largely, if not wholly, transferable to the printing of buildings and other larger-scale structures, and perhaps to printing approaches beyond depositional techniques. However, one important exception to this idea of transferability is that, unlike desktop and many industrial objects, buildings and other large structures may be less tiltable or relocatable after printing, thus potentially increasing their natural DFP demands or constraints.

By contrast, another likely set of exceptions to this transferability centers around the greater overall cost and complexity of printing relatively large and more heterodox or multi-lithic structures. This elevated cost and complexity may allow the economical use of mechanical aids to support or augment materials during the printing process – such as the use of permanent and removable formwork (ranging from traditional decking to airforms). Again, the greater expense of buildings also may permit integration of various modular elements or components, via robots or human labor, before, during, or after the printing process, and all in a way that may not be economically or practicably feasible in small-scale printing.

BUILDING DESIGN IMPLICATIONS

While the above general DFP principles may broadly carry forward to 3D printed building design, it is worth touching on some of the specific design considerations the technology suggests for wholly or significantly printed buildings. As a preliminary summary of key building printability issues, and to spur your thinking in this area, let me highlight several crucial ideas and themes:

> Integral design – as with 3D printed objects of all kinds, there will be great advantage in selecting materials and design forms in tandem and with the goal of their combination forming a fully or nearly complete building solution out of the nozzle, so to speak

> Layered design – since buildings are naturally more complex or involve more needed outcomes than many smaller objects – from thermal and internal air control to mechanical systems and weatherproofing – this suggests that, absent significant new advancements in materials science, the potential for fully integral, monolithic, or single-print designs will be naturally limited to some degree, and in turn that layered printing is more likely to be the norm

> Structural reinforcement – while robotic or human placement of reinforcing elements before, during, or after building printing is plainly possible, the practice of including reinforcement measures within the printing process – for example, within or alongside printed materials, via their overall shape, or through multi-layer printing – is likely to provide significant cost and durability advantages

> Foundations – as touched on before, 3D printing in all its forms requires a stable base upon which to build, but it is unclear if traditional foundation construction methods will continue forward into an era of printed buildings, with the clear potential for both site excavation (or milling) and foundation placement to become fully automated

> Walls – instructively, today’s early prototype 3D printed structures (example 1, example 2, example 3) often print the building walls only,  employing simple curves and articulation to strengthen long wall segments, suggesting that the printing of vertical or modestly tilted walls will be the least challenging aspect of 3D printed buildings

> Floors – in contrast to walls, the 3D printing of floors, especially elevated ones, will require significant design and engineering attention to be practicable, and is likely to involve special measures to allow horizontal printing and ensure a durable result – including the use of non-printed formwork, the use of temporary and permanent printed buttresses, and/or insertion of modular decking or ground-printed floor members

> Roofs – representing a middle condition of complexity between walls and elevated floors, the roofs of printed buildings either may constructed more traditionally (as demonstrated here and in some of the early prototypes links above) or they may employ curved shapes for both structural and waterproofing reasons – otherwise, 3D roofs will need to be printed much like elevated floors, especially if they are designed to be flat or in the form of non-curved spanning inclines

> Weatherproofing – building on these ideas, most 3D printed buildings of course will need to be weatherproof to some degree, and specifically to shed rain and other precipitation, again suggesting curved or heavily buttressed 3D printed roofs as just outlined, or the avoidance of 3D printed roofs and building capping via other methods

> Doors, windows, & mechanicals – as highlighted before, these important aspects of modern building do not appear to lend themselves to 3D printing techniques in the near term, with some exceptions (such as sprayed membranes for solar energy collection), though eventual robotic fabrication and placement of these elements is clearly possible

> Overhangs & ornamentation – in keeping with our discussion, building overhangs and other jutting features will be less desirable, have a lower DFP quotient, and will require more design attention to be practicable, but other forms of building appendage and ornament of course are plainly possible, though more intricate ornamentation is likely to require smaller printer nozzles and thus perhaps a separate or secondary printing process

Today, 3D printing of buildings is in its infancy and proof of concept stage. But forward-looking designers and planners especially should begin to prepare for this technology, since it is almost certainly coming, and sure to be disruptive when it does. In particular, 3D printing may dramatically change the way buildings look and are constructed, alter regulation and inspection needs, reduce initial and long-term costs, and increase overall efficiency and sustainability.

As a simple, awareness-building next step in this process, you might begin to assess the printability of the designs you are working on or see proposed around you. In the meantime, I welcome your comments and questions on this important set of ideas.

Mark Lundegren is the founder of ArchaNatura. 

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