Save our houses! – CLOSED



The quality of the existing housing stock is confronting the municipalities of Haarlem and Zaanstad with major challenges in the area of foundation repair. The foundation problem is urgent. Many homes are built on wooden piles (mostly pine), which can be affected by bacterial or fungal rot. Approximately 22,500 homes are at risk: 10,000 private homes, 12,500 housing association homes built before 1945 and a further 10,000 private and housing association homes built between 1945 and 1970 run the risk of wooden foundation rot. Foundations can be replaced in various ways, but such repair work is extremely expensive (between €40,000 and €60,000) and time-consuming. The psychological burden on owners can be severe: some of those affected cannot finance these costs. This often causes the owners many years of great uncertainty about the possibilities for repair.  A prolonged postponement of the repair means further deterioration in the foundation quality and an increase in the resulting damage to the building structure. When the quality of a home falls to a level at which safety is compromised, the city council may issue a statutory notice. This means that the owners are legally obliged to restore their home. Owners who cannot afford this may ultimately be forced to sell their property, with the risk of residual debt (loss of value due to foundation problems and any existing damage caused by these problems). In light of the importance for the municipality (safe and sound buildings) and the social and financial importance of repairing these homes, the municipalities of Haarlem and Zaanstad wish to increase the number of foundation restorations completed each year.

We therefore seek a solution that ensures that these foundation repairs or parts thereof can be carried out in a smarter and more efficient way, with the goal of being able to repair more homes in less time and at a lower cost.


The Challenge:

Find a smarter and more efficient way for us to predict and/or repair foundations and thus make these homes safe and sound.



Issued by: the municipalities of Haarlem and Zaanstad.