Obviously Dutch law applies to a purchase contract. It is common knowledge that an oral agreement is legally binding within the Netherlands. However, there are a few exceptions and one is that there is no binding agreement as long as there isn’t a signed contract when buying a house privately. This gives you some time after you come to terms with the seller about price and other conditions regarding the sale. After agreement a draft is made of the contract. In general it takes about a week before it is formalized. You can use this time to have a structual survey done by a building inspector.
Why this advice? It saves you the money involved in having a survey done before you even know whether an agreement is met and you are still early enough to renegotiate or walk away if something unexpected comes up.
If a seller refuses you to have a survey done then the only good advice is to walk away from this property