Building owners, designers and contractors are increasingly realizing the benefits of modular prefabrication. This trend, transforming the way construction components are delivered, is helping speed projects to market and leading to higher quality buildings.
The switch from stick-built construction to the assembly of manufactured components also makes the fabricator’s role more important than ever. Yet every manufacturer faces limitations that can impact their capabilities in delivering the optimum system to the jobsite.
When designers factor in manufacturer limitations, they can better select partners that can deliver the best possible end product.
Three challenges in particular must be addressed:
1. Factory machinery’s capability limitations.
Compared to assembly in the field, manufacturing large system components in the factory presents a number of benefits in quality, safety, scheduling, and other areas. The benefits are limited only by the manufacturer’s capabilities, including the following:
- Machinery size. The size of the available assembly table, kiln or other equipment will dictate the size of the finished component. A manufacturer’s capabilities can best be assessed by breaking down a design based on the capabilities of their machinery.
- Local codes. Does the manufacturer’s machinery solution meet the local codes? For example, in the U.S. and UK, a welding machine is an acceptable solution for forming the rebar for a prefabricated concrete slab. In many Nordic countries, code prevents use of this type of machine.
- Machinery layout. Lines must be organized so that a bottleneck does not delay the entire product’s delivery. By adopting a Design for Manufacturing and Assembly approach—with the use of universal connectors—manufacturers can outsource a single component or system that can easily be assembled in the factory or onsite.
Limited space presents challenges for prefabrication delivery processes.
2. Limited space for storage and staging areas.
Manufacturers must address upfront two challenges in the logistics of getting product onsite:
Highway size limitations. Federal governments set minimum height and width requirements that will limit the size of pre-assembled systems. In addition, oversized products typically must be transported in daylight hours with an escort.
The space available for storing product. Factories cannot be stopped at the first sign of a site delay. If a problem arises on the site, a manufacturer may suddenly be faced with the need to store, for example, 1,000 housing modules. And what happens for manufacturers producing for multiple sites, where suddenly two sites experience delays? Having a buffer zone, such as a lot or warehouse space situated outside the factory or just off the jobsite, can be essential.
Bidding processes don’t account for delivery and other realities of modular products.
3. Poor outcomes due to competitive bidding practices.
Today the reigning belief is that the best price comes from competitive bidding. Yet the bidding process actually is more likely to lead to the worst possible price. The bid component truly leads to about 15 percent of the 30 to 35 percent overrun most projects face as a result of redundancy.
There are two reasons for this:
Delivery is not addressed upfront. By creating a generic design that multiple parties are able to bid, there is no possibility of optimizing against the delivery process. By creating a time and material contract that uses the delivery process as the starting point, projects will come out with a better price.
Unknown factors lead GCs to bid high. Every project faces unknown variables, be it weather or an unforeseen site challenge. These factors cause contractors to pad their bid. But by working directly with the trades who will address these unknowns, it’s possible to get early insight into potential challenges.
Room for Improvement
The off-site or near-site manufacture of building systems leads to a more repetitive, reliable process. These processes can be simulated and studied for further optimization. By working with manufacturers as partners in the design process, projects can gain an edge in schedule, budget and quality.