Group Executive Board

Tjerk van der Meer (1974)
Chief Executive Officer
Deerns Group

Tjerk van der Meer serves as Chief Executive Officer of Deerns Group since March 2021, after joining as a member of the Group Executive Board in Q3 2019.

With a background in engineering and business, Tjerk occupied various international and management positions at Royal BAM and Royal HaskoningDHV earlier in his career. Latest before joining Deerns, Tjerk was globally responsible for commerce and strategy in the Manufacturing & Technology sectors at Arcadis.


Roel Rooskens (1967)
Deerns Group

Roel Rooskens is CFO of the Deerns Group and member of the Group Executive Board since January 2012. Prior to joining Deerns in 2011, Roel has worked in various financial roles within the Telecom and IT industry and lastly as a Group Controller for the Insulation & Rooflights division of a large building materials company, CRH.

He holds a degree in Economics from Tilburg University, The Netherlands. In 2004 Roel completed the RC Post Master Controllers Programme at the Nyenrode University, The Netherlands.


Jan Karel Mak (1957)
Executive Board Member
Deerns Group

Jan Karel Mak served as Chief Executive Officer of Deerns Group from July 1999, when he joined the firm. On 1 March 2021 he transferred his CEO role to Tjerk van der Meer while remaining a Member of the Executive Board.
After graduating in Environmental Sciences (Wageningen University) Jan Karel worked as a consulting engineer, project manager and managing director at engineering firms DHV and Arcadis, and as a management consultant at McKinsey & Company.

Among Jan Karel’s other activities are Board roles in various charitable organisations as well as supervisory and coaching roles in several Dutch technology companies.