First, let’s define:
Overbuild is a technique used to add extra stories on top of an existing building, maximizing development area-per-square-foot. Overbuilds often use as much of an existing building as possible adding extra support as needed. Since limited demolition is required, overbuild projects generally have quicker turnaround than new construction.
Infill is the development of vacant lots surrounded by existing buildings, converting once-dormant land into a vibrant residential or commercial structure.Because of their location, infills have easy access to existing public infrastructure– a cost savings for developers.
Three reasons why wood is ideal for vertical expansions:
- It’s lightweight. Wood’s light weight makes it a natural choice for overbuild designs, whether mass timber or light-frame construction. In addition to helping maintain a building’s original architecture or design, wood’s light construction footprint may allow tenants to remain in an existing building during construction, as opposed to evacuating while internal columns are strengthened to support heavier materials. With 20 percent of the density of concrete, timber also proves advantageous when building on sites with a poor foundation material. As with7overbuilds, wood’s lightweight nature is one of several differentiators that make it optimal for infills. Wood tends to use less construction equipment than other building materials, therefore facilitating infill projects in tight, complex urban spaces.
- It’s cost-friendly. Opting for an overbuild can offer cost benefits, with additional savings by using mass timber construction. When wood and mass-timber products are prefabricated and delivered ready for installation, construction time, equipment needs and on-site labor costs may be reduced. In addition, wood is one of the most cost-friendly building materials, saving builders 20 percent in some cases. In many cities, infill real estate is costly, so wood’s comparative10cost advantage also helps ensure a project’s overall financial health. In many cases, building five-six stories using wood is the only way an infill project is financially viable.
- It’s eco-friendly. In addition to performance and cost benefits, wood’s lower carbon footprint offers an environmental gain to America’s housing crisis. According to the U.S. Green Building Council, buildings account for 39 percent of America’s yearly carbon dioxide emissions. Wood is the only building material made from a renewable resource, and its ability to capture and store carbon differentiates it from competing materials like concrete and steel. Analysts estimate that the construction of timber buildings for new urban dwellers could store up to 680 million tons of carbon a year, with these carbon benefits lasting throughout the building’s lifespan. A recent mass timber expansion of an15existing building in London removed over 1,000 tons of carbon from the atmosphere. The project, which added 50,000-square-feet of new office space, took just eight weeks to complete.