Prefabrication experiments - 485 - On- and Offsite management

Dealing with difficult climate conditions, labour shortages, or even health and safety issues on building sites seems to point toward greater offsite uptake as an obvious solution for improving construction's productivity and efficacy. The enduring fragmentation of the sector made up of many small contractors and trades managing their projects on a one-by-one survival-of-the-fittest model has led to a construction industry that is not only conservative but is refractory to any type of change or innovation. Buildings in general still go up inefficiently the same way they have been for the past hundred years and industrialization, while promising an integrated model for producing other commodities, has led to a disjointed process isolating designers from fabricators and builders.

 

Construction has become about managing disparate subtrades and coordinating an onsite entanglement of systems or tasks, that,  at best is ordered by a proficient general contractor or at worst a convoluted mess of discordant contractual relationships. While the building industry’s fragmented culture is difficult to shift on a dime toward harmonized practices, one of the current drivers for reform is the impetus to efficiently respond to the environmental crisis, by reducing waste and gaining any competitive advantages linked to streamlining potential efficiencies.

 

This potential swing toward reducing waste is where construction management and offsite fabrication can be tuned to operate in a just-in-time symbiotic relationship to deliver value added subcomponents. The pre-assembly model is different from basic modular volumetric or panelized systems as it is based on what makes sense to prefabricate and can yield greatest results in terms of time management. The overlap of onsite and offsite tasks is an untapped opportunity to apply manufacturing principles to construction. The constructor-manufacturer integration model also presents challenges, as traditionally companies have specialized in one or the other. However, the benefits of managing tasks ideally suited to their off- or on-site conditions can create a different type of prefabrication company based on managing project processes rather than completely separating construction and manufacturing, which only leads to further entanglement of stakeholders.

Just-in-time delivery of a preassembled chunk

Prefabrication experiments - 484 - Competitiveness and Timesavings

 

Advanced manufacturing, big data optimizations along with precise resource management are all combining to generate all manner of efficient fabrication and labour-saving production processes. This is the case in nearly all sectors. Why haven’t these translated to a competitive edge for prefabrication deployed toward building construction? This simple question relates to offsite construction and manufacturing requiring different cost structures, an enduring obstacle to a sustainable uptake. Most agree, prefab reduces timelines; if time is money, prefab should be much cheaper when compared to onsite conventional construction. Time savings have not necessarily translated to economies on one-off projects. Higher upfront planning costs, greater factory overhead, entanglements caused by on- and off-site coordination and steep learning curves for inexperienced stakeholders can increase overall expenditures.

 

When compared to other manufacturing sectors where industrialization has optimized quality, while reducing time and costs per unit, architecture remains bogged down in singular prototypes. Each building includes far too many contextual specificities to justify the mass production flows required to consistently lower costs. Replicating details, components, processes over multiple projects can present opportunities for bulk purchasing and regulating supply chains, however, varying loads, soil conditions, environmental constraints, management requirements in dense urban areas, ever-changing stakeholders, and code obligations all differ from one site to another occluding stable demand for normalized designs that would induce important savings.

 

Notwithstanding the one-off contextual intricacies, reduced timelines should still translate to savings in overall project costs. A condensed schedule of even a modest 10-15% on a standard timeline can minimize interest payments on loans, site management costs like heating for winter conditions, equipment rentals and even deliver earlier earning potentials, an important advantage in housing or production facilities. A structured global cost analysis and comparisons should be applied to offsite construction by including some type of time equivalent factorization. The archaic nature of onsite construction is still mired in analysing construction costs in terms of management, labor and materials. Reforming costing methodologies is one of the important cultural shifts required to increase offsite construction’s potential market penetration.

Extracted from https://www.ellismodular.com/why-modular/ 

Prefabrication experiments - 483 - Constant, stable purchase order pipelines

 

One of the most important differences between the on-site subtrade or contractor and the off-site manufacturer is the need for consistent purchase orders with similar characteristics; A constant portfolio (often referred to as a pipeline) is required to cover important investments in everything from marketing to tooling, all essential for high quality and quantity fabrication. 

 

On-site contractors benefit from logistics that are defined and managed according to a single project. Specifically in a conventional design-bid-build process contractors estimate and then purchase all specified elements to build a building and their risk is limited to these purchases. Risk is also mitigated by the fact that any cost overruns that are incurred because of omissions or unforeseen conditions will, in the end, be assumed by the client. 

 

Along with all the same functional, technical and economic criteria of an onsite project, off-site fabricators need to amortize costs over repeated productions. This creates conditions that constantly challenge the economics of high-value-added prefabrication. The bipolar objective of responding to a client’s one-off prototype criteria while managing large overhead costs of manufacturing is completely foreign to onsite builders and thus defines the lack of competitiveness of offsite versus onsite at least when it comes to delivery of one-off projects. 

 

Offsite manufacturing can only be economically feasible if project pipelines permit advanced planning and resource management to justify just-in-time flows that balance sales with bulk purchases. When comparing the bidders' supply chain between two competing companies, one onsite and one offsite, the overhead required to sustain the prefabricator’s advantages, compared with the jobsite contractor who assumes lower overhead linked to project specific tools and materials, is difficult to overcome. Further, materials for the onsite contractor are paid for as claims progress on site. 

 

Unstable demand that does not sufficiently replicate certain elements will never be a viable avenue for off-site construction, if the objective is to reduce costs. The crux of the problem is that ingrained architectural singularity occludes the potential for large-scale project pipelines - this simple but hard to crack polarity has spelled the end for many promising prefab experiments.

Similar characteristics in manufacturing of modular volumetric