The construction industry is underperforming. According to McKinsey & Company, “ … construction has seen a meager productivity growth of 1% annually for the past two decades.” During those same decades, the manufacturing industry has drastically reduced project time and cost. This is partly through a process called Design for Manufacturing and Assembly (DfMA). The DfMA methodology is used in the early stages of design to evaluate and improve production and assembly. Like manufacturing, construction consists of many working parts. The use of DfMA in the construction field is an emerging trend. Employed in the UK as well as Singapore, DfMA can help reduce some of those working parts, thereby increasing the productivity and value of commercial projects.
Initially developed from the research of Dr. Geoffrey Boothroyd, DfMA draws from two related concepts. “Design for Manufacturing,” or DFM, focuses on the parts of a product. The product design is evaluated, including steps, materials, or components that can be substituted or eliminated to minimize the complexity of assembly. “Design for Assembly,” or DFA, focuses on the assembly of the parts. This includes the ease of assembly, including the time and process used, again eliminating any superfluous steps. DfMA is a combination of both concepts, leading to an overall design that allows a component to be thoughtfully constructed in a method that reduces waste and increases productivity.
DfMA in Construction
Drawing from “Lean” principles implemented in manufacturing and other industries, DfMA evaluates and optimizes a process within construction. DfMA differs in that it is a collaborative approach between experts from all stages of the construction timeline. Imagine designers, engineers, suppliers, and contractors working together, both on a product and the process for delivery. Essentially, both design and production considerations will inform the final product.
All of this talk may sound like modular, or offsite construction. According to Tan et al., (2020),1 “Even though offsite construction is quite similar to manufacturing and hence presents an unprecedented opportunity for DfMA, they are not the same. Some major components can be manufactured, e.g., in an offsite precast yard, but a considerable portion of the construction and assembly work are still conducted onsite.”
Tan proposes these guidelines for DfMA in construction, all of which are integrated into the design process when using DfMA in construction. These include:
- Technology-rationalized design;
- Context-based design;
- Logistics-optimized design;
- Component-integrated design;
- Material-lightened design.
These guidelines integrate the use of offsite or modular construction, but with a thoughtful and tailored approach to the design and overall need of the project.
Context-based design considers both the physical and sometimes cultural environment in the design and assembly process. Looking at the physical environment takes into account the weather as well as the overall site composition and location. A project based in a humid climate prone to flooding would have vastly different needs than one based in a dry, frigid environment. Additionally, the culture must also be considered. Perhaps a modern steel and glass structure would be out of place in a community with historic brick homes and shops. Technology-rationalized design strikes a balance between prefabrication and on-site assembly. Again, DfMA is not modular or completely prefabricated structures. Instead, it considers the overall project, how much time is needed for assembly, and who is working on-site. Consider a project that requires a building façade that meets needs for both aesthetics and the ability to withstand a humid climate. With technology-rationalized design, using more complicated on-site masonry may be the better choice than using a prefabricated component. While a prefabricated facade may make installation faster, it may sacrifice longevity. Logistics-optimized design considers the transport of prefabricated or partially-assembled components both inside of the factory as well as to the construction site. Additionally, it looks at how those components are placed on-site to make the assembly of each part as efficient as possible.
It is worth noting that lightweight buildings first emerged to alleviate the problems of manufacturing overcapacity and lack of social housing after World War II. Material-lightened design aims for material and structural efficiency when creating the volume of space. It has the goal of limiting the impact of the overall construction on the environment as much as possible. Attention is focused on light timber, light steel, and components that are easy to handle in size and weight. Reduction in overall building weight helps to improve efficiency in activities related to manufacturing and assembly. Component-integrated design relies on “Design for Manufacturing” practices, such as evaluating the drafting and combination of these lighter, more efficient pieces, as well as simplifying the steps for assembly. For example, reevaluating the type and number of connection joints while considering the newly lightened materials may vastly improve and streamline the building process. These streamlined components can make production, transportation, and onsite manual work more convenient.
Could DfMA Benefit Your Project?
DfMA is a thorough reworking of a product or process, requiring significant time and resources at the beginning of a project. It also requires a commitment to the process by all stakeholders. Engineers, architects, contractors, and suppliers must be willing to collaborate and accept feedback on their designs and processes.
Benefits can include:
- Consistent output – once a project, process, or component undergoes the DfMA process, it is now optimized for consistent and efficient assembly.
- Safety – with more activities removed from the construction site, there is potential for fewer accidents.
- Decreased time and labor – the use of premade components in a delineated manner can decrease the amount of labor and overall time needed for a construction project.
1 Tan, Tan et al., Construction-Oriented Design for Manufacture and Assembly Guidelines, 146 Journal of Construction Engineering and Management (2020), available here or here.