For three days, CM Company oversaw the installation of the first Cross-Laminated Timber (CLT) panels in the state of Idaho as part of the new branch extension of the Boise Public Library! being built at Bown Crossing. The project, designed by FFA Architects of Portland, Oregon, uses the versatile panels as a roof and ceiling structure over the main reading rooms, gallery and entry of the building. Some of the panels, most of which are ten feet wide, span nearly forty feet between the steel beams.
CLTs are a building technology relatively new to North America, but which have been used in Europe for several decades. They are a composite wood material, made by gluing and pressing layers of standard dimension lumber together at 90 degree angles, alternating each layer until the required thickness is achieved.
Essentially plywood panels made out of 2×6’s, CLTs can be used as decks or walls in many of the places where reinforced concrete or steel structure would usually go. Since they are a composite material, their size is limited only by the machines that produce them and shipping constraints (the Library!’s CLT panels were fabricated in Vancouver, B.C. and shipped to Boise, Idaho by truck).
Because they are designed and cut to fit specific places in the building, CLTs make large assemblies relatively rapid. The Library!’s three day installation timetable was actually due to a limited staging area at the site, meaning that only about a third of the panels could be stored at a time. Panels were flown in the mornings and the next day’s shipments were delivered in the afternoons.
With the city’s desire to make the Library! a LEED building, CLT panels are an important aspect of the design. Since they are made from very large quantities of wood, CLTs actually absorb and store more carbon from the environment than their production puts off, in stark contrast to concrete or steel. So not only do they have a very low environmental impact, they are also one of only a few truly renewable construction materials.
We look forward to using more of this incredible product in the future!
