A mass-timber, low-carbon, vertical extension office solution

Building upwards with tall timber

There has been a renaissance in tall timber construction in Europe and the UK over the past decade, but high-rise mass timber has been slower to take off in the US, partly due to restrictive code requirements. Versions of the International Building Code (IBC), adopted in most US jurisdictions including DC, cap the height of timber buildings at 85 feet, a height exceeded by 80 M. 

To gain approval for 80 M’s exposed mass timber overbuild, our integrated team of mass timber experts worked closely with Hickok Cole and the DC code authority to demonstrate that our proposed solutions fulfilled current fire and life safety code requirements and aligned with the standards of the 2021 IBC to allow mass timber buildings of up to 12 stories. 

Opened in September 2022, the project is the first high-rise overbuild timber structure in North America.

Sustainable biophilic design: the advantages of mass timber

Mass timber is steadily gaining traction in the US market as developers and designers recognize the cache and commercial potential of sustainably sourced and built projects and more states and municipalities seek new ways to cut carbon emissions in the building sector. As a renewable material, timber carries a significantly lower carbon footprint than conventional building materials such as concrete and steel. There is also a growing consumer demand for biophilic-inspired designs that take health and wellness into consideration to maximise the occupant’s connection to nature. 

Columbia Property Trust, the developer behind 80 M, was quick to embrace the mass timber solution proposed by Hickok Cole and Arup. Both highly sustainable and aesthetically appealing, the exposed mass timber design differentiates 80 M from standard Class A office buildings in the competitive Navy Yard commercial area. Moreover, mass timber’s lighter weight enabled the client to maximise vertical build while minimising structural strengthening interventions to areas outside of tenant spaces, saving capital and allowing the building to remain fully operational during construction.
 

Modernising mass timber code requirements 

Arup is a recognised leader in mass timber design and construction. Our experts collaborate with fire research institutes across the world to improve our understanding of how the new generation of multi-story timber buildings behave in a real fire, so that designers and regulators can identify risks and devise solutions that meet or, in many cases, exceed existing code requirements. We also advise suppliers on testing procedures to ensure certified solutions, and undertake fire testing for project-specific solutions, including on 80 M.

Featuring mass timber

As the first mass timber structure in Washington DC to exceed 85ft, Hickok Cole’s design had to be carefully vetted by the DC code authority before earning approval. The structure’s connections were a critical focus. Due to the lack of fire-tested connections on the market, Arup’s structural and fire engineers developed new concepts for 80 M’s two-hour rated exposed timber connections. These connection concepts were further designed and tested by Katerra, the timber design-assist partner, with our help. Once it was clear that the connections and redundant systems proposed for the building delivered a high level of safety, Arup demonstrated the design’s viability and safety to the code authority, ultimately helping 80M to win approval. 

Solar photovoltaic (PV) array: Cost/benefit analysis and procurement strategy

As part of the project review process, the building owner chose to include a photovoltaic (PV) array on the roof of 80 M to align with the ambitions of the local zoning board. We helped the client fulfill this request by rapidly performing a feasibility study and cost benefit analysis. This analysis found that a combination of savings garnered through local and federal tax incentives, the solar renewable energy credit, and utility cost savings, brought the time horizon for return on investment down from 16 years to four years. Our engineers and consultants also leveraged their knowledge of the local market and permitting department, available technology, and procurement timelines to help Columbia Property Trust develop an owner request for proposal to evaluate bids.