Is my house at risk of foundation problems?

Houses built before 1970 often stand on wooden piles or on shallow foundations without piles ('op staal'). Whether such a foundation gets damaged depends on the type of foundation, the soil and the groundwater. The foundation knowledge centre KCAF and the Netherlands Enterprise Agency (RVO) have made a map of the areas where the risk is likely to arise first: the indicative areas of concern.

How many homes are affected

Until roughly 1970, buildings in the Netherlands were often given a foundation on wooden piles, or a shallow foundation. According to RVO, about 750,000 buildings stand on a wooden pile foundation. Such a foundation is sometimes vulnerable, especially in areas with a soil of lower bearing capacity or a low groundwater level.

What the map says, and what it does not

Per postcode area the map sets the number of buildings from before 1970 against the soil: low peat, the river area, marine clay, closed-off sea inlets and tidal areas. Where many old buildings stand on such soil, attention is at least warranted. KCAF and RVO made the first version in 2017. The map makes no statement about the actual condition of a foundation: only an on-site survey can tell you about a single house. Home valuers use the map as well.

The reverse also holds: a postcode outside the areas of concern is no guarantee. The map looks at the soil and the year of construction, not at the type of foundation of a building or the groundwater level in the street.

Why wooden piles get damaged

Dry exposure: if the groundwater drops below the top of the wood, it can start to rot.
Negative skin friction: subsiding soil drags on the piles.
The soil: wooden piles are damaged mainly in areas with soil of lower bearing capacity, such as low peat, river clay, marine clay and tidal areas.

How to assess the risk

The year of construction: before 1970 a wooden pile or shallow foundation is likely.
The soil: clay and peat are more vulnerable than sand.
Cracks, crooked doors and windows or a sunken floor are warning signs.

What you can do before you buy

A sale is a logical moment to check the foundation; that is why the model purchase agreement for homes contains a standard clause about it. If in doubt, have a foundation survey done. A structural survey looks along, but does not measure the foundation. Repair is usually the responsibility of the owner or the owners' association (VvE); as a private individual you can take questions to KCAF. The Fonds Duurzaam Funderingsherstel (a foundation repair fund) helps owners repair their foundation.

What the government does

Through the National Foundation Problems Programme (Nationale Aanpak Funderingsproblematiek), RVO works on behalf of the Ministry of the Interior to improve knowledge of foundation problems: research into countering bacteria in wooden piles, topping up groundwater to preserve foundations, and guidelines for foundation surveys.

What the Perceelscan does with it

The report says which area of concern the postcode area is in, how many buildings there are from before 1970 and the year the building was built.

Does the KCAF map tell me whether my house has foundation problems?

No. The map shows per postcode area where attention is needed, based on the number of old buildings and the soil. Only a foundation survey can tell you about a single house.

Which houses are most at risk?

Houses on wooden piles or shallow foundations, often from before 1970, on soil of lower bearing capacity such as low peat or clay. How much risk a single house runs also depends on the type of foundation and the groundwater.

What is dry exposure?

When the groundwater is lower than the top of the wooden piles, the wood is exposed to air and can start to rot.

Who pays for repairing a foundation?

Usually the owner or the owners' association (VvE). The Fonds Duurzaam Funderingsherstel helps owners with this.

Sources

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Updated on 25 October 2026