For generations, construction has been fairly straightforward. You dig a hole, put up some walls, slap a roof on it, and you have a structure.

The advent of off-site construction in the late 20thcentury turned that model on its head, taking much of the planning, designing, and fabricating of new buildings away from the actual site, allowing things to come together in pieces and projects to be completed much faster than usual. They’re also easier to customize and can quickly be built to the customer’s specs. Off-site building includes componentized, panelized, and modularized elements that are brought together to create structural and interior partition systems. 

That’s the good news.

The bad news is that off-site construction includes a range of materials, scales and systems, etc that impact the quality and resiliency of the final product. It isn’t like with a traditional, site-built structure, where the materials used are fairly uniform. In an off-site building, the sky is the limit and so are that applications. Sometimes, components that would work well in one part of the country or climate would be entirely inappropriate in another. Or sometimes local areas have structural design requirements that others don’t have.

Here are a few questions to ask when considering an off-site built structure.

Does it use cross-laminated timber?

Cross-laminated timber (CLT) is a type of prefabricated, solid engineered wood. It’s lightweight and very strong, with superior acoustic, fire, seismic, and thermal performance. For these reasons, it is becoming a popular alternative to conventional materials like concrete, masonry, or steel, in construction. 

Each CLT panel consists of several layers of lumber boards stacked in alternating directions, bonded with structural adhesives, and pressed together to form a solid panel. Finished CLT panels are exceptionally stiff, strong, and stable, handling load transfer on all sides.

It’s a good structural product for use in floors, walls and other long-run applications.

Does it have structural insulated panels? 

Structural insulated panels (SIPs) are a high-performance building system for residential and light commercial construction. According to the Structural Insulated Panel Association, an industry group, these panels “consist of an insulating foam core sandwiched between two structural facings, typically oriented strand board (OSB).  SIPs are manufactured under factory controlled conditions and can be fabricated to fit nearly any building design. The result is a building system that is extremely strong, energy efficient and cost effective.”

SIPs are becoming popular as an alternative construction material that helps builders save time, money and labor. “Building with SIPs generally costs about the same as building with wood frame construction when you factor in the labor savings resulting from shorter construction time and less jobsite waste. Other savings are realized because smaller heating and cooling systems are required with SIP construction.”

What about the roof?

Panelized construction isn’t just limited to walls and interiors. Roofs as well can be constructed off-site and installed as part of the structural design of a new building.

These roof systems, which are made of either wood or metal, combine long-span glued laminated timber framing with a panelized plywood or decking. Sections of the roof can be assembled on the ground in lengths and then lifted into place. These systems mean shorter construction time, minimized the amount of work required up on the roof itself, and helps prevent falls and injuries on the site. As a structural component, panelized roofing like this is stronger than a traditional roof, sometime eliminating the need for extra bracing and framing.