If you’re in the construction industry, chances are you have some experience with off-site construction. In fact, a recent study by the National Institute of Building Sciences (NIBIS) found that more than 87 percent of respondents used off-site construction to some extent in 2018. And, more than 81 percent plan to use the method the same amount or more throughout 2019.
What is driving this trend—and is it here to stay? How can this approach transform the way you tackle future projects? In this article, we will share the answers to these questions based on our expert knowledge of off-site manufacturing and construction.
What is off-site construction?
Off-site construction refers to the design, fabrication, and assembly of elements at a location other than the actual site where they will be installed. The method involves prefabrication of various building elements, such as walls, panels, and other structures which are transported to the construction site for installation once completed.
According to the NIBS study, the most common off-site techniques used are precast/prefabricated concrete, HVAC and plumbing assemblies, curtain wall assemblies, and metal building systems.
Historically, off-site construction has been used for large projects—the Empire State Building and the Eiffel Tower are two mammoth examples—but technology, as well as innovations in construction materials and processes, have led to the use of this construction method on all types of projects.
As building material costs continue to rise and skilled labor dwindles, the use of prefabricated construction becomes even more alluring to many contractors. Some contractors are even establishing factories (both temporary and permanent) dedicated to pumping out prefabricated structures that can be quickly transported and installed at the construction site.
What are the benefits of off-site construction?
When construction takes place in a controlled environment, production goes faster. Workers don’t waste time looking for tools or waiting for space. Everything they need is accessible in an organized setting.
You also don’t have to contend with the weather, which can slow down on-site construction. Better yet, various structural elements can be constructed simultaneously, which is must faster than the sequential approach that often accompanies on-site building.
Prebuilt structures are easier to install, requiring fewer people and less machinery. This equates to safer working conditions for those who are on site.
More than 70 percent of the NIBS study respondents named scheduling advantages as a main benefit of off-site work. When multiple elements are prefabricated off-site, the overall project timeline is shortened. Once on the site, prefabricated elements go up quickly, delivering incredible time savings.
In on-site construction, there are a lot of contingencies. You don’t know how much the weather will slow you down, and how that might impact the amount of labor hours you need to complete the project.
These contingencies all but disappear with off-site construction. You know exactly how much material, time, and labor is required to complete the work because it is done in a controlled environment.
This makes budgeting and estimating project costs more predictable. Less material waste and faster production time (which reduces total labor hours required) reduce the overall cost for construction projects.
Consistent and improved product quality
The off-site factory setting, whether temporary or permanent, produces better quality structures due to the controlled environment. Consistent finishes on elements that are perfectly sized install more easily and yield a higher quality end product.
Reduced environmental impact
Less on-site construction reduces the traffic congestion that typically comes with it. Additionally, prefabricated elements are cut to size perfectly at the factory, reducing errors and the associated wasted materials.
Both of these side effects of off-site construction reduce the negative environmental impact projects can have.
Is off-site the future of construction?
Despite the spread of off-site construction, there are some barriers to even greater adoption:
- Culture—Contractors and builders are embracing the off-site approach slowly but surely. We are seeing a greater acceptance given the gains in productivity, quality, and cost savings, so it is just a matter of time before a full cultural and mindset shift occurs.
- Design limitations—Off-site construction can be a bit limiting when it comes to design options, making it hard to meet the unique specifications of some projects.
These barriers are slowly coming down as the need to increase productivity with fewer skilled laborers continues to challenge the industry. New technologies and innovations are also making off-site more appealing and easier for contractors and construction companies to adopt.
UHPC and off-site construction
Ultra-High Performance Concrete (UHPC) is an innovative concrete technology that is not only stronger and more durable than traditional concrete, but it is also thinner and weighs less. In fact, concrete wall panels made with UHPC are 25-33 percent thinner, making them even easier to transport and install on-site. UHPC is also more flexible than regular concrete, so even structural elements with complex designs can be fabricated off-site.
UHPC is also very adhesive, making it an ideal candidate for use in prefabricated bridge elements and systems (PBES). In this type of off-site construction, specific elements of the bridge are made off-site, such as deck and beam elements, abutments, and superstructure systems.
The use of PBES delivers all of the benefits previously mentioned for off-site construction, but they require strong field-cast connections. Previously, connections were expensive, difficult to construct, and lacked durability. UHPC changed all of this with its superior bonding quality. UHPC connections are easy to manage, require less material and maintenance, and can be completed in less time compared to traditional concrete.
The bonding quality is so strong that PBES pieces can be joined together with minimal disruption to the precast panels. The Federal Highway Administration (FHWA) even named UHPC connections for PBES as one of the Every Day Counts (EDC) initiatives, demonstrating the government’s support for this new material and its benefits in off-site construction bridge projects.
Nineteen states and Washington, DC are currently demonstrating and assessing the use of UHPC connections in bridge building. Four additional states—Georgia, New Jersey, Pennsylvania, and Rhode Island—have made UHPC connections a standard practice on bridge projects with PBES.
Building Information Modeling (BIM) software
Off-site planning needs to be integrated from the start and requires collaboration and communication between all those involved in the project. BIM software allows construction companies to take a proactive role in the planning process, making off-site construction more manageable and successful.
Improvements in the software enable project and team members to manage quality, reduce risk, and keeps team members connected to critical project data in real time.
This may be a glimpse into the crystal ball of construction, but 3D printed concrete walls are here. The US Marines even 3D printed a concrete bridge over the course of just three days, so this technology will certainly add to the speed and ease of off-site construction.
Adoption by major companies
Big names such as Google and Marriott are embracing off-site construction, which will encourage more construction companies to follow suit.
Marriott has found that using off-site construction dramatically decreases the amount of time it takes to construct a new hotel. For example, their Folsom Fairfield Inns & Suite opened just seven months after Marriott received the building permit. Other large hotels are adopting off-site construction for new projects.
The future of construction is off-site. As advances in technology and materials continue, more construction projects will rely on the off-site method. Better quality, reduced project time, and cost savings are just some of the reasons behind this shift. Contractors and construction companies that make the move off-site sooner rather than later place themselves in a more favorable position when it comes to winning contracts, making it a wise approach to invest in today.