Do CMs have a role in Cross Laminated Timber Structures? I returned to the Apex Plaza (described on these pages in April 2021, The Last Word on CLT – Cross Laminated Timber) to find out. On my prior trip, I marveled at the beauty of the fully exposed beams, columns, and CLT floor panels. But, at that time, none of the finishes had been applied. I wanted to see how much evidence of the wood structure would be retained, and where our conventional wood components might work.
Since April, this eight-story building has been acclaimed on TV “making history” (TV Station NBC29), and in print “Going Class A” and “The first CLT building in the East” (The Daily Progress). Class A buildings are the “most modern, state of the art, buildings with high-quality finishes” according to the Building Owners and Managers Association (BOMA).
The most wall-panel-friendly feature of these mass timber buildings is the accuracy and workability of their framing. Since the beams, columns, and most connections are designed and shop built to fit tightly together, the openings they form are nearly “dead-on” per plan. In the Apex building, for example, many dozens of exterior glass panels were fully assembled off-site, trucked 70 miles, unloaded, and hoisted into place. According to job superintendent, Paul Hahn of GC Hourigan Construction, every panel fit properly, with less than one inch clearance. The aluminum frames were simply screwed into the surrounding framing.
In the unique case of these glass panels, no site modifications were possible. But for the remaining openings, factory-built wall panels would have been ideal, and fastening them to the structure would have been just as easy. However, steel studs were specified, and Hourigan did not pursue pre-fabrication.
From the outside, there is no evidence of the wood bones beneath this handsome structure. Though it has a distinctly modern and environmentally friendly façade, it seems like any other typical Class A building. Yet prospective tenants will quickly realize the differences inside.
Therein lies one of mass timber’s primary advantages: that it requires minimal finish work. Apex Clean Energy, the owner and primary tenant, is not covering the ceiling panels and beams, but had to apply gypcrete to the floor for sound-deadening. Another tenant has incorporated acoustical ceiling tile between the beams but has left the columns and the bottoms of the beams exposed. For interior partitions, if fire codes allowed, pre-building wood wall panels would seem preferable to piecing together steel studs and tracks on site. But with either material, the top and bottom plates (tracks) are easily screwed into the wood structure, expediting finish-out.
The architect for Apex Plaza, William McDonough + Partners, is currently designing scores of mass timber structures. Who will be the first component manufacturer to supply one of them?