Our team
Daan
Sustainability thinker & building practice
Daan has worked at Kosterman Bouw since 2022 and is currently in the process of taking over the business. With years of experience in sustainability and circularity at a modular builder, he puts theory into practice. He's always searching for the perfect detail, the right materials, and a smooth building process that leads to happy clients. When Daan isn't working, you'll find him cycling, doing calisthenics, or cooking.
Jack
Carpenter with an eye for sustainable design
Jack is a skilled carpenter who combines a deep knowledge of sustainability theory with a craftsman's eye for detail, applying both to the practical world of bio-based construction.
He grew up in Southern England, and moved to the Netherlands in 2024. The son of a talented furniture maker, he applies timber knowledge and millimetre accuracy throughout his work.
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Jack first studied climate science, followed by an MSc in Sustainable Development, before working in environmental policy consultancy. Despite loving the work, Jack was drawn to a career path where he could use his hands alongside his knowledge.
Jack joined Dovetail Design and Build in Bristol, and completed his training with the company under the exceptional guidance of Will Hallet and Nigel Shelborne. He joined the prestigious Carpenters Fellowship in 2021, a collective preserving historic carpentry skills in the UK. Jack has since worked in several countries including Spain, Peru, Colombia, and now the Netherlands. Anywhere he has worked, he has found that the bio-based construction sector is filled with people who want to do the right thing and work with the future in mind.
After moving to the Netherlands in 2024, Jack reached out to Daan and the two of them started brainstorming about the company they could build. Working with sustainable materials and practices was obvious to them both, as was the way they wanted to create a positive work culture and healthy relationships with clients.
Outside of work, Jack is a passionate surfer, furniture maker, rugby lover, bird watcher, occasional marathon runner, and most importantly a loving new father. You’ll find him year round diving into the North Sea with his board.
Karel
Founder & solutions artist
Karel is the heart of Kosterman Bouw. He's been in construction his entire life, incredibly solution-focused and down-to-earth — sometimes you even need to slow him down a little. After 30 years, he's gradually passing the torch, but he stays involved behind the scenes. When Karel isn't working with a hammer in his hand, he's busy perfecting his sourdough bread recipes!
Maud
Team Assistant
Maud supports organisation and planning, and also captures our projects on camera. Punctual, decisive and creative — she keeps things organised and shows our work at its best.
Simone
Administration & big-picture thinking
Simone is the organisational backbone of the company. She keeps an overview, handles the administration, and picks up anything that falls outside the lines. With her big-picture view and vision, she makes sure everything runs smoothly.
A bit of history
Kosterman Bouw traces its roots back to Karel Kosterman, son of a contractor from Wijk bij Duurstede. In 1995, he founded Kosterman Peek Bouw together with his cousin Henk.
Using prefab elements, they built extensions at record speed, often within three weeks, and also took on new-build and major renovation projects. At its peak, the team had ten people working in it.
After the financial crisis, the company continued with fewer people, which — surprisingly — suited it well. In 2019, Henk retired and Karel focused entirely on prefab timber construction, changing the company's name to Kosterman Bouw. When Daan decided to join in 2022, it created room to carry the business forward under the next generation. The takeover becomes official in 2026.
Why we're different
We combine traditional craftsmanship with innovative, sustainable building. Our projects are often biobased, circular, and designed with an eye for detail. But just as important:
- We work personally and with genuine involvement.
- We communicate honestly and transparently.
- We make building fun again — for ourselves and for our clients.
Where we work
Kosterman Bouw is based in Cothen, a small village in the province of Utrecht. We carry out many projects in the surrounding area, such as Wijk bij Duurstede, Utrecht city, Driebergen, Culemborg and Zeist. In our workshop in Cothen, we manufacture many of the core components for our building projects, as well as custom carpentry. Equipped with modern machinery and the latest safety systems, the workshop allows us to work efficiently and carefully. It's also a place we genuinely enjoy being: music in the background, shared coffee breaks, and room for craftsmanship. Not a factory, but a great workplace where clients are always welcome to discuss their plans.
Contact
Aan de slag dan maar!
T: 0343-745295
Kosterman Bouw
Alexanderweg 77-06
3945 CH Cothen
info@elementhoutbouwers.nl
BTW: 868205904B01
KvK: 97729922
