Atlassian Central, the 39-story hybrid timber tower rising above Sydney’s Central Station, reached its full height of 180 meters on July 22, 2026, making it the tallest hybrid timber building in the world and pushing the record roughly 100 meters past Milwaukee’s Ascent tower. The topping-out ceremony, confirmed by developer Dexus and co-owner Atlassian, marks the structural finish line on a $1.45 billion build that has become the industry’s clearest proof point yet that mass timber can carry a commercial office tower into supertall territory, even as the code framework that would let U.S. developers attempt something similar is still filling in state by state.

What actually topped out

Atlassian Central is not a pure timber building. It is a hybrid: a steel exoskeleton provides lateral strength around a seven-story concrete podium, and above that, three cross-laminated timber (CLT) floor levels are sandwiched between steel-and-concrete mega floor plates in each of seven four-story sections the design team calls “habitats.” In total, timber runs through 21 of the tower’s 39 stories, using more than 30,000 cubic meters of European spruce CLT and glulam supplied by Sweden’s Stora Enso and Austria’s Wiehag. Structural engineering came from Taylor Thomson Whitting, with SHoP Architects and BVN as designers and Built and Obayashi Corporation as the construction joint venture. Dexus targets a six-star Green Star rating and says the timber-steel hybrid halves upfront embodied carbon compared with a conventional premium office tower of the same size. Practical completion is set for late 2026, with Atlassian occupying five of the seven timber habitats starting in late 2028.

The supply chain tell

The detail worth flagging for anyone tracking capacity is where that timber came from. Australia has domestic CLT and glulam production, but Atlassian Central’s structural timber was sourced from Northern Europe, not from an Australian mill. For a marquee project willing to spend $1.45 billion and chase a world height record, the decision to import European spruce panels rather than specify locally says something about where the deepest, most fire-tested tall-timber manufacturing capacity currently sits. Stora Enso and Wiehag have built reputations on large-scale, tightly tolerance-controlled CLT for exactly this kind of load path, and that track record still outweighs freight costs and lead times on a project of this scale. The same dynamic shows up domestically: developers in states without in-state CLT or glulam production continue to source panels from Pacific Northwest or Southeastern mills, or from Canadian and European suppliers, adding weeks to procurement timelines that specifiers need to build into schedules now rather than discover during shop drawing review.

The code catches up, unevenly

The regulatory backdrop for tall timber in the United States has moved in the developer’s favor, but the map is still patchy. The International Code Council’s International Building Code (IBC) has included three tall mass timber construction types, Type IV-A, IV-B and IV-C, since the 2021 edition, permitting mass timber in buildings up to 18, 12 and nine stories respectively. The bigger change arrived with the 2024 IBC, which lets Type IV-B projects expose 100% of mass timber ceilings, up from the 20% ceiling exposure and 40% wall exposure allowed under the 2021 edition. That shift, grounded in full-scale mass timber compartment fire testing run at Sweden’s Research Institute (RISE), directly addresses one of architects’ most persistent complaints: that earlier code language forced expensive gypsum wrapping over timber surfaces owners specifically wanted visible. As of this summer, all 50 states have adopted some version of the tall mass timber provisions, but only 18, including California, New York, Washington, Oregon, Illinois and Georgia, have moved to the 2024 IBC and its expanded exposure allowance. The other 32 states are still working from the 2021 edition’s tighter limits, which means the same design a specifier can build in Seattle may need to be reworked for a jurisdiction still on the older code.

Momentum beyond the icons

Atlassian Central and Ascent generate the headlines, but the broader project count is where the sector’s growth actually lives. WoodWorks, the nonprofit technical arm of the Wood Products Council, now tracks 2,833 mass timber projects across the United States, up from three in 2009. Market researchers cited in recent trade coverage put the global mass timber construction market at $390 million in 2025, projected to reach $1.07 billion by 2033, a 13.1% annual growth rate. New entrants are chasing that growth from different angles: Cambium, a wood marketplace, says it is digitizing timber sourcing contracts and grew revenue fivefold last year; Generate.design, which automates mass timber structural design and quoting, says it worked on more than 100 projects last year spanning residential buildings to data centers and claims roughly 30% carbon savings against comparable concrete structures. On the ground, affordable and workforce housing is where volume is showing up fastest, including a 550-bed mass timber student housing project at Metropolitan State University of Denver set to open in fall 2027 and EverGlen Village in Bellevue, Washington, five mass timber buildings delivering more than 1,000 affordable senior housing units.

What to watch

Specifiers working in one of the 32 states still on the 2021 IBC should confirm with the local building official whether a local amendment has already adopted the 2024 exposure language ahead of the state’s formal code cycle, since several jurisdictions move faster than their state timeline suggests. Mill capacity and lead times deserve the same scrutiny that lumber futures get on this beat: with WoodWorks’ project count climbing into the thousands and international suppliers still winning marquee jobs over domestic capacity on projects like Atlassian Central, panel availability, not code allowance, is increasingly the binding constraint on project schedules. Dexus’s practical completion date at the end of 2026 and Atlassian’s occupancy in late 2028 are the two milestones worth tracking for how a hybrid timber tower of this scale actually performs once occupied, from fire and life-safety commissioning to the embodied-carbon claims the developer is making publicly. Insurance underwriters and structural engineers watching the RISE compartment fire data that underpins the 2024 IBC’s exposure allowance should also expect that dataset to get cited repeatedly as more U.S. jurisdictions consider adopting it over the next code cycle.