The law provides that the owners' meeting decides by an absolute majority of the votes cast, unless the articles provide otherwise (article 5:127(1) BW). The Model Regulations 2017 define this as more than half of the votes cast at the meeting; blank votes, invalid votes and abstentions do not count (article 54.1).
Example: six valid votes are cast, four for and two against. Four is more than half of six, so the proposal is adopted. Three for and three against is not a majority: the vote is tied, and under the Model Regulations 2017 the proposal is deemed to be rejected (article 54.2).
Note the difference with decisions that require a qualified majority, such as two thirds or four fifths.
See also: Qualified majority, Quorum, Tied vote (staking van stemmen), Voting rights (stemrecht)
Read more: Quorum and majorities in a VvE
Legal basis: Boek 5 BW, art. 5:127, Modelreglement 2017, art. 54