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The Sawmill In The City

New York is known as a city of masonry and metals with its ubiquitous visible bricks, stones, decorative terra cotta, cast iron facades, and sheet metal cornices, which is why Old Structures Engineering has titled its guide to the structure of New York buildings City of Brick and Steel. Peering inside this book, just like peering inside New York buildings, one additionally finds a lot of wood. In fact, the fascinating paper “Harvesting New York” by Dan Bergsagel (of Schlaich Bergermann Partner and Scale Rule CIC) and Timothy Lynch (of the New York City Department of Buildings), estimates that 95% of New York City’s buildings are made of wood-frame or masonry and wood construction.

In the outer boroughs there are numerous timber-frame buildings, and in Manhattan only a fraction of buildings feature non-combustible construction. Most buildings across the city of six or fewer stories have timber floor framing, but as those floors tend to be hidden behind plaster, few people outside of the renovation business give that hidden wood much thought. Much of the wood that was used before the twentieth century was high-quality old-grown timber, which is denser and stronger than the commercially grown timber that is widely available nowadays. Surprisingly, there is very little strategy, let alone governmental guidance, in NYC about how to deal with this valuable resource stored in our building stock. Given the high rate of renovation, demolition, and new construction in the city, a phenomenal amount of lumber each year gets removed from buildings, most often making its way into a landfill.

Harvesting New York” uses Department of Buildings data to estimate that 14 million m3, or about half a billion cubic feet of wood, is contained in New York City buildings. Furthermore, they project that yearly about 14,000 m3 (500,000 cubic feet) of wood gets released through renovation or building demolition. To put that number in perspective, the annual amount of removed wood in New York City is roughly equivalent to one third of the annual output of softwood dimensional lumber in all of New York State’s sawmills*. Of course, a lot of that wood could, and from an environmental viewpoint should, be recycled, but that unfortunately does not happen nearly enough. There are some challenges to structural reuse of salvaged wood such as regrading and de-nailing, but those can easily be overcome**. Also, if structural reuse is not feasible there are other possible alternatives being developed to keep the wood from being discarded, such as using excess wood to create cross laminated timber (CLT) or similar products. This seems particularly pertinent now that environmental considerations are becoming an increasing focus of the construction industry due to concerns with climate change. Keeping wood is not only a great way to save on energy cost associated with producing and transporting other materials, but it is also an excellent way to keep the carbon dioxide sequestered. 

What strikes me most, is that recycling and reuse is well ingrained within the construction industry in New York, with respect to other materials, in particular metals. If unneeded copper is found in a building, the construction manager will typically call “the copper guy”, who will pay for the copper which is therefore meticulously gathered and saved. In contrast, it is still commonplace to cut up a series of gorgeous undamaged timber joists and throw them in the dumpster as observed in the top photo, despite the existence of some wood reclamation businesses in the city.*** To address this issue, we need to raise awareness of the numerous potential economic and environmental advantages to preserving wood. Further data on financial and environmental impact**** would be a great start and eventual citywide incentives or ordinances could help get us to a place where construction managers have “the wood guy” on speed dial. 

*As estimated by Dan Bergsagel, the primary author of “Harvesting New York,” based on the USDA’s Softwood Sawmills in the United States and Canada Profile, Research Paper FPL-RP-659 (2009)

**At Old Structures we always ask contractors to repurpose wood within the same building to the extent feasible.

***OSE was not the engineer at the project pictured, we were subcontracted to oversee a small aspect of the façade stabilization.

**** To the best of our knowledge this data is not yet available. Stay tuned for some collaborative research on that in the future.