Sarah Buchner spent more than a decade in construction before founding Trunk Tools, an AI startup for the industry. She grew up in a low-income household in Austria, where her father was a carpenter and brought his children to job sites when the family needed extra money. Buchner began working as a carpenter as a teenager and eventually became a general contractor managing large projects in Europe.
Her career took a turn after one of her workers died on a job site. "Once you realize that people die under your management, you just look at life differently," she said. The experience pushed her to build a health and safety app, which led to a Ph.D. focused on data science and early AI in construction. During that research, she found that construction companies produce enormous amounts of information, but it sits fragmented across systems and buried documents.
"The data was there, but it was so messy and so unstructured" that traditional analytics couldn't usefully process it, she said.
From Stanford student to construction-tech founder
In 2019, Buchner moved to California to attend Stanford Graduate School of Business. She founded Trunk Tools in 2021 while still in business school and graduated in 2022. The company, now based in New York, did not find its first meaningful product-market fit until 2023, when advances in large language models made working with unstructured information more practical.
Trunk Tools integrates with construction systems and analyzes the 3 to 4 million pages of documentation an average project involves. The company sells primarily to general contractors and subcontractors, and has begun working with project owners. Its more than 10 live AI agents review contracts and drawings, flag inconsistencies, help with specifications and bidding, and pass information between workflows. On one instance, an agent calculated that a requested change would add nearly $4 million to a roughly $100 million project, and the owner decided against it.
The company has raised about $70 million from Insight Partners, Redpoint, and Innovation Endeavors. Revenue grew fourfold last year and is on track to grow roughly 3.5x this year, according to Buchner. Its most recent round was a $40 million Series B in 2025, valuing the company at $325 million.
An unconventional founder advantage
Fundraising was harder at the start. "I think it was hard very early on because I might not look like the traditional tech founder," Buchner told TechCrunch. But once Trunk Tools gained traction, her industry background became an asset. She spent years doing the work her customers do and can answer detailed construction questions in investor meetings.
"I walk into a room full of investors, and I know that I'm definitely the smartest person in the room when it comes to my industry," she said.
That experience matters in a sector that has been slower to adopt new technology. Contractors operate on thin margins, and Buchner believes the distance between the executives buying software and the workers in the field affects adoption. She still sees AI being taken up faster than other tech in construction. The company now provides training and change-management services to help large companies roll out AI.
"I'm just thinking about solving a problem," she said.
Buchner expects her industry background to keep shaping how Trunk Tools builds for the industry, rather than following a conventional software business model.
Why this matters if you're in construction
If you manage projects, the bottom line is clear: The typical construction site produces millions of pages of documentation, and AI systems are becoming able to process the complexity that outmatches a human brain. When a change order comes in, you'll soon be able to calculate the second- and third-order effects before committing to work - get that right and you avoid paying for change work a project owner may not otherwise approve.
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