How A Teenage Carpenter Became The Founder Of AI Construction Startup Trunk Tools

Editor鈥檚 note: The following is the second profile in a series of articles about startup founders from non-technical backgrounds who have launched successful venture-backed companies. Read the previous interview with founder here.

Before founding , an AI startup for the construction industry, spent more than a decade working in construction. She grew up in a low-income household in Austria, where her father was a carpenter. When the family needed extra money he would take his children to job sites, and Buchner began working as a carpenter as a teenager.

鈥淚鈥檓 a blue-collar worker by background,鈥� she explained.

Buchner never really left the industry. She worked her way up and eventually became a general contractor, managing large construction projects in Europe. But her career took a turn after a worker died on one of the sites she was running.

Experiencing the fatality changed the way she thought about her work.

鈥淥nce you realize that people die under your management, you just look at life differently,鈥� Buchner said.

Sarah Buchner, founder of Trunk Tools. (Courtesy photo)

She decided to build a health and safety app for construction workers. That company was separate from (and before) Trunk Tools, but the project pulled Buchner into software and eventually led her to pursue a Ph.D. focused on data science in construction and early artificial intelligence.

While doing that research, she realized something that would later become central to Trunk Tools: Construction companies produce huge amounts of information, but much of it is fragmented across different systems and buried in documents, making it difficult to analyze.

鈥淭he data was there,鈥� Buchner said, but it was 鈥渟o messy and so unstructured鈥� that traditional data analytics could only go so far.

Turning construction data into an AI business

Buchner saw an opportunity to make that information more useful. She also decided she wanted to build the company in the U.S. rather than Europe.

In 2019, she moved to California to attend . She founded Trunk Tools in 2021 while she was still in business school, graduating in 2022. The early years were messy, as they often are for startups, and Buchner said the company did not really find its first meaningful product and market until 2023.

By then, advances in large language models were beginning to make it more practical to work with large quantities of unstructured information.

That was particularly relevant in construction. Buchner estimates that an average construction site can involve 3 million to 4 million pages of documentation spread across numerous systems. Trunk Tools integrates with those systems and creates a layer on top that can analyze the information and use it to carry out various tasks.

The company sells primarily to general contractors and subcontractors, and has also begun working with some project owners.

Trunk Tools鈥� AI agents can review contracts and construction drawings, flag inconsistencies and help with specifications, submittals and bidding, and pass that information among different workflows. For example, one agent can uncover an issue in a drawing and give that information to another agent to figure out next steps and how any changes might affect other parts of a project.

Such an ability to connect information across a project is important because construction projects are unusually complex, Buchner said.

鈥淔or a human brain, it鈥檚 impossible to calculate the second- and third-order effects of changes because of how complex and connected it is,鈥� she said.

In one case, Buchner said, a project owner requested a change that a construction company might otherwise have simply begun implementing. Trunk Tools calculated that the change would add nearly $4 million to a roughly $100 million project. Once the contractor presented the cost to the owner, the owner decided not to proceed.

In another instance, a worker got chemicals in their eye, and someone nearby used a Trunk Tools agent to ask what to do. The system returned step-by-step instructions for responding to the exposure.

鈥淲ith stuff like that, you have to act fast,鈥� Buchner said, calling it a particularly meaningful example for the company.

From early product to rapid growth

New York-based Trunk Tools now has more than 100 employees. Buchner is a solo founder and said her Ph.D. gave her enough of a technical background that she did not feel she needed to seek out a technical co-founder. She did, however, hire experienced AI engineers early and has since built out a larger technical leadership team.

The startup has also expanded the number of products it offers. Buchner said Trunk Tools had two live AI agents about a year ago and now has more than 10. The pace of development has become fast enough, she said, that the company sometimes struggles to train its own sales and customer-success teams on new products as quickly as they are being released.

The company has raised about $70 million in funding from investors such as , and . Revenue grew fourfold last year and is on track to grow roughly 3.5x this year, according to Buchner. Its most recent funding round was a $40 million Series B in 2025 that valued Trunk Tools at $325 million.

An unconventional founder advantage

Fundraising was more difficult at the very beginning, Buchner shared, in part because she did not fit the mold investors often associate with startup founders.

鈥淚 think it was hard very early on because I might not look like the traditional tech founder,鈥� she said.

But after Trunk Tools gained traction, Buchner believes her industry background became an advantage. She had spent years doing the work her customers do and could answer detailed questions about construction in investor meetings.

鈥淚 walk into a room full of investors, and I know that 鈥� I鈥檓 definitely the smartest person in the room when it comes to my industry,鈥� she said.

Bringing AI to a tech-wary industry

Historically, the construction sector has been slower than others such as finance and legal services to adopt new software or technologies. One reason for this, Buchner believes, is that there is often a long distance between the person buying a product and the person expected to use it.

Executives may make purchasing decisions while sitting in an office. Meanwhile, the actual users are often out in the field working on job sites and under constant pressure to keep projects moving. Contractors also typically operate on relatively thin margins. So if a bad decision is made around purchasing technology, the potential cost is greater.

Still, Buchner believes that AI is being adopted faster than other technologies she has seen enter the construction industry.

Over time, Trunk Tools has also learned that simply selling the software is not always enough. The company now provides training and change-management services for customers trying to roll out AI across large organizations.

It鈥檚 another area where having an industry background makes a difference, in Buchner鈥檚 view. Rather than sticking to a model of what a conventional software business is supposed to look like, she said, she is more focused on what construction companies actually need.

鈥淚鈥檓 just thinking about solving a problem,鈥� she said.

Looking back, Buchner said she always expected to start a business someday. For years, she assumed it would be her own construction company.

Instead, the carpenter-turned-contractor ended up building a software company for the industry she had already spent much of her career working in.

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