Sietse started his architectural career at LTS Architecture at the former Willem Blaeu in Alkmaar. After completing LTS Architecture, Sietse continued his school career at Horizon College in Alkmaar. There he successfully completed primary and secondary carpentry training.

After a short trip to the construction site (1999), Sietse discovered that his interest is in calculating, preparing and supervising construction projects. After completing the Calculator / Work Planner course at Horizon College in Alkmaar, he came into contact with the budgeting and calculation of construction projects in civil and utility construction. To broaden his knowledge in the field of architecture and business economics, he followed a B&U calculation course at BOB training and Small Business and Retail Management at INholland in Haarlem.

From 1999 to 2012 and from 2016 to 2019, Sietse worked as a calculator / planner, project manager and manager at various medium-sized contractors in North-Holland. From 2012 to 2016 he owned his own building management agency. The company focused on independent calculation, preparation and start-up of various projects both in the Netherlands and abroad.

Since 2019, Sietse has been working as a project manager and construction cost consultant at IGG. In addition to drawing up estimates and budgets, and testing budgets, he can consult on construction costs form initiation to execution phase using his practical architectural experience. In this way he can also contribute to making complex construction and technical issues practical.