Known for its intrinsic aesthetic charm and adaptability, wood presents limitless opportunities within the field of construction and design. In addition to fostering a sense of warmth and sophistication, it serves as a sturdy structural component for projects. Mass timber construction, characterized by its utilization of sustainably sourced solid wood panels, represents a sustainable, energy-efficient alternative to conventional steel and concrete structures. This innovative approach to building offers a host of competitive advantages and long-term benefits, including lower carbon footprints, accelerated project schedules, and reduced labor force on site.
Mass timber assembly is easier and faster than traditional construction methods. Commonly prefabricated off-site using precision technology, this reduces time spent on-site, minimizes traffic and disruption to surrounding communities, and cuts project schedules nearly in half. Mass timber is lighter than traditional construction materials, making it less expensive to ship compared to steel. This benefit enables architects and designers to explore creative and innovative designs that may not have been feasible with heavier materials.
Home-Grown Building
Located next to the bustling Ponce City Market in Atlanta, Georgia, 619 Ponce (619 Ponce at Ponce City Market – JE Dunn Construction) is a four-story mass-timber building. The project offers 93,000-SF of office building and 27,000-SF of retail space. JE Dunn Construction is proud to work alongside Jamestown and Handel Architects to construct the first “home-grown” building in the state of Georgia.
The building’s structure is harvested from Georgia-grown timber, while most wood for mass timber projects are imported from other countries. Beams and floor slabs are constructed with southern yellow pine sawtimber harvested from Georgia forests, including supplies from timberland that Jamestown owns and manages in Georgia. “Our site has about 50 trailer loads of mass timber materials delivered and manufactured from less than 200 miles away,” explains JE Dunn Senior Project Manager, Chris Hughes. This method reduces transportation emissions and maximizes the sustainability benefits of mass timber. Slated to open this year, 619 Ponce is targeting LEED v4 and Fitwel certification, and net zero carbon ready operations. The project aims to leverage best practices for material specification, minimizing chemicals of concern, reducing embodied carbon, and supporting the local economy by sourcing materials locally where possible. From predictability and strength to product performance and sustainability (2023 Environmental, Social & Governance Report – JE Dunn Construction), mass timber offers owners many benefits. Not only is the amount of wood quickly replenished, but it also leaves a much lower carbon footprint while building than traditional materials such as steel.
The Construction Process
Mass timber construction projects involve several critical phases and activities. The unique preconstruction process is crucial to the success of the overall project. The most important element of this process is procuring the timber. JE Dunn is well versed in this vetting process which includes assessing multiple types of wood, domestic vs. international shipping, and upfront coordination with manufacturers to ensure timely delivery to the project site.
Once the wood arrives to the jobsite it is craned directly from the truck and swiftly positioned as the race to erect the building begins. The team’s top priority is to protect the wood; therefore, the materials are treated like a finished project throughout the entire construction process. Water management is critical during this process. Our team on the 619 Ponce project created a detailed water proofing plan to ensure the wood was continuously protected from the elements.
BIM coordination is essential during the mass timber construction process. At 619 Ponce, the BIM model ensured each hole for the wood screws were in the correct place. Additionally, our team used BIM modeling to ensure the integrity of the wood was not compromised by overloading areas with ductwork and piping. The team’s primary focus was on system coordination, ensuring seamless integration with the exposed timber structure while maintaining aesthetic appeal. JE Dunn implemented a unique, raised floor system using BIM. The team utilized two-by-fours and plywood with sand infill, not only enhancing acoustic properties but also providing tenants with designated space to run conduit and systems beneath the floor. By minimizing element exposure, such as wiring and conduit, the team created a seamless environment for tenants.
Prefabricated and engineered for durability, mass timber checks the boxes when it comes to strength, acoustic, seismic, and fire performance and comes in a variety of types. While the method depends on each project, our team has the expertise to work collaboratively during design to explore all options, allowing owners to make informed decisions.
Fire Resistance
Some may worry about fire safety when using large quantities of timber for a project. The good news is that mass timber offers similar fire resistance comparable to steel and concrete. Mass timber elements such as cross-laminated timber (CLT) panels can range from 3 inches to 12 inches in diameter. Mass timber has a charring layer, which provides insulation to the interior layers of the wood, protecting them from the heat. Even though mass timber loses material during a fire, it retains load bearing capacity. According to thinkwood.com*, a 5-ply CLT panel wall lasted for 3 hours and 6 minutes during a fire resistance test. During the test, the wall was exposed to temperatures exceeding 1,900 Fahrenheit. This wall lasted well beyond the two-hour rating that building codes require. Mass timber also tends to behave more predictably than steel or concrete in a fire. Steel can experience sudden collapse when exposed to high temperatures while concrete can crack under extreme heat.
Speed of Construction
Mass timber buildings go up quickly. Since mass timber panels are prefabricated and then assembled on site, they have much shorter project timelines and safer construction sites. Much of the prefab process includes the use of Computer numerical control (CNC) machines which allow for precision cuts, eliminating wasted material. Wood is placed only where it is needed. Another advantage of factory-based manufacturing is the high level of repeatability. The ability to quickly, safely, and cost-effectively repeat building processes makes mass timber an attractive option for large-scale, frequent projects like multifamily housing developments, where efficiency and sustainability are key priorities.
* Citation: MTCC_Factsheet.pdf (thinkwood.com)