The knowledge of spatial arrangements of objects is an important component for the design of migratable user interfaces that target pervasive environments. Objects in these environments are often moving around individually, which leads to a highly dynamic and unpredictable environment. Due to its nature, spatial information cannot be described exhaustively, and uncertainty and imprecision need to be taken into account during both the design phase and at runtime. We present an approach to model dynamic spatial information, providing it with the ability to interpret to some extent uncertain and imprecise knowledge. We then integrate this type of spatial-awareness into ReWiRe, a framework for designing interactive pervasive environments, in order to improve its user-interface distribution techniques.