Steps away from Martin Luther King Jr. Blvd. in Downtown Savannah, 110 and 111 Ann Street, collectively known as Ann Street Lofts, are Choate’s inaugural cross-laminated timber (CLT) projects and the first CLT structures to be built in southeast Georgia. Together, these multi-family projects bring premium amenities, two levels of below-grade parking, and nearly 400 luxury apartment units to the coastal city.

Manufactured by Binderholz in Fügen, Austria, Ann Street’s CLT panels consist of layered lumber boards stacked in alternating directions to increase tensile and compressive strength. The layers are glued together and pressed to form a solid, rectangular panel that is used as a load-bearing element in structural systems. Since all of the panels are prefabricated in Binderholz’s facility in Austria, the project team coordinated an intricate plan at the start of the process to set the stage for a quick and easy onsite assembly that generates almost no waste.

 

Building Through Virtual Design

Critical to planning, coordinating, and executing the installation of CLT at Ann Street, is the Building Information Model (BIM) produced by Choate’s VirtualWorks department. Long before construction began, the Choate team, in concert with key trade partners, created a virtual replica of the building that incorporates all design elements, structural systems, and utilities. Through the model, the team can simulate and test their assembly processes, make necessary adjustments, and avoid delays during construction.

The Many Benefits of Cross-Laminated Timber

First and foremost, the large wood panels that constitute CLT buildings are remarkably fire-resistant. Thick pieces of timber, such as a 12-inch-diameter log, are extremely difficult to ignite, and once lit, tend to self-extinguish. During an intense fire, the outer layer will begin to char, but the interior maintains its structural integrity for several hours.

CLT is also more sustainable than traditional materials like concrete and steel. Wood is 100% renewable, has superior insulation properties, and stores carbon dioxide. Like all plants, trees are “carbon sinks,” meaning they store more carbon than they release, even after being manufactured into lumber. Conversely, steel and concrete generate carbon during their production due to the burning of fossil fuels. Additionally, CLT reduces excess material waste that comes from cutting materials onsite, because each panel is prefabricated to millimeter precision before leaving the factory.

Finally, because CLT buildings have prefabricated panels, they can be constructed faster which reduces labor costs and safety risks. Similar to a set of Legos or Lincoln Logs, the wooden panels are quickly pieced together like a 3D puzzle, each piece fitting perfectly with those around it. For example, the CLT portion of 111 Ann Street, equating to five floors and roughly 146,000 SF, took a stunningly short 12 weeks to install.