Large parts of the Netherlands sit on peat and clay, too soft to build on directly. Until roughly 1970, houses were therefore founded on wooden piles. Those piles last centuries as long as they stay submerged — if the groundwater level drops, the pile head dries out, fungi get to work, and pile rot (paalrot) begins.
The risk is strongly location-specific. The Zaanstreek, parts of Rotterdam, Schiedam, Dordrecht, Gouda, Haarlem and the older Amsterdam districts are known for foundation problems. A house of the same age on sandy soil in the east of the country generally is not. Build year and soil together determine the risk, not build year alone.
Signs you can spot yourself at a viewing: cracks in the brickwork that are wider at one end, doors and windows that stick, visibly sloping floors, a facade out of plumb, and a widening gap between the front doorstep and the pavement. Fresh plaster on exactly one wall is a reason to ask more questions, not a reassurance.
The cost is why this matters. Foundation repair on an ordinary terraced house runs into tens of thousands of euros and, for a full replacement, can reach six figures depending on method and access. It is also uninsurable: foundation damage falls outside buildings insurance because it is not a sudden event.
In a terraced house you can almost never repair your foundation alone — the whole block has to go together, which makes you dependent on your neighbours and their finances. In an apartment it sits with the VvE: ask for the long-term maintenance plan and whether anything has been reserved for foundation work.
What you can do beforehand: ask the seller whether foundation investigation has ever been carried out and whether any repair was done, and if so ask for the report. A standard building survey does not look below ground; foundation investigation is a separate, specialist job involving inspection pits. In a risk area that few hundred euros is money well spent.
Lenders watch this too. A property with known, unrepaired foundation problems can be harder to finance, and a valuer who flags it may mark the market value down — which feeds straight through into how much you are allowed to borrow.