Sarah Buchner, a former carpenter and general contractor from Austria, founded Trunk Tools in 2021 to bring AI to the fragmented data landscape of the construction industry.
Her startup, now valued at $325 million after a $40 million Series B in 2025, uses AI agents to analyze millions of pages of construction documents, flag inconsistencies, and help contractors calculate the real cost of project changes—preventing costly mistakes and improving site safety.
Buchner's decade-plus industry experience, initially a liability in venture fundraising, proved essential to building a software company that solves genuine construction problems rather than imposing off-the-shelf tech.
What happened
Sarah Buchner, who spent over a decade in construction before pursuing a Ph.D. in data science, founded Trunk Tools in 2021 to apply AI to the construction industry's fragmented data. The New York-based startup now has more than 100 employees, offers more than 10 AI agents (up from two about a year ago), and raised a $40 million Series B in 2025 valuing the company at $325 million.
Why it matters
Construction sites generate 3 million to 4 million pages of documentation spread across disparate systems, making it nearly impossible for humans to calculate the cascading effects of project changes. Trunk Tools' AI agents connect this information across workflows—in one case flagging that a requested change would add nearly $4 million to a roughly $100 million project, saving the contractor money and the owner from costly mistakes. Buchner's construction background, once a barrier to fundraising, became a competitive advantage: she can credibly advise investors and customers on industry-specific needs that conventional software vendors often miss.
What to watch
Revenue grew fourfold last year and is on track to grow roughly 3.5x this year, according to Buchner. The company has raised about $70 million total from investors including Insight Partners, Redpoint, and Innovation Endeavors. Trunk Tools now pairs software sales with training and change-management services, recognizing that adoption in a traditionally tech-wary industry requires more than just product delivery.
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Sarah Buchner's path to founding Trunk Tools is rooted in a specific problem she encountered during her decade-plus career in construction: massive amounts of data scattered across incompatible systems and buried in unstructured documents. As she pursued a Ph.D. in data science and construction AI, she recognized that traditional analytics could not handle the scale and mess. The real breakthrough came when large language models matured enough to make working with unstructured information practical—a timing that aligned with her business school years at Stanford (2019–2022) and Trunk Tools' founding in 2021.
What sets Trunk Tools apart is not just the technology but Buchner's understanding of construction's unique complexity and conservatism. The sector has long resisted software adoption, partly because the economic stakes are high (thin margins mean a bad tech investment can be catastrophic) and partly because the distance between purchasers and end users creates misalignment. By embedding domain expertise—training, change management, and a focus on what contractors actually need rather than what software vendors traditionally sell—Buchner has built a company that construction firms trust. The concrete examples she cites (the $4 million cost avoidance, the chemical-exposure protocol) show that AI in construction is not about automating rote tasks but about making sense of complexity that human brains cannot easily process at scale.
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