TDQS was founded in 2015 by respected industry professionals Jan Theunissen and Corey Ducasse, both of whom brought with them a wealth of experience from leading Quantity Surveying and Property Development firms. Their shared vision was to establish a consultancy built on technical excellence, integrity, and long-term client partnerships.
Over the past decade, TDQS has evolved into a trusted name in the built environment—delivering accurate, strategic, and future-focused quantity surveying solutions across a diverse range of projects. Our reputation has been shaped by our commitment to quality, innovation, and consistently adding value to our clients.
Founder member of TDQS with over 18 years of experience in the construction industry, holding a BSc QS and BSc QS (Hons). Specialises in cost planning, contract administration, construction law, and critical thinking, with a portfolio spanning industrial, commercial, conservation, housing, and medical facility projects.
Holds a BSc in Property Development and BSc (Hons) in Quantity Surveying, with over 10 years of experience in construction cost management. Has successfully managed numerous retail and residential projects from concept to completion, with expertise in cost planning, estimating, budgeting, and procurement.
In early 2025, we experienced the great loss of Corey Ducasse, whose leadership, passion, and professionalism remain deeply woven into the fabric of our company. In his honour, TDQS continues to uphold the values he championed—striving for excellence, maintaining the highest standards of service, and building strong, enduring relationships.
Today, TDQS stands as a testament to the vision Jan and Corey shared. Under Jan’s continued leadership, and with a skilled and passionate team at its core, the firm looks to the future with purpose and momentum.