The article questions representationalist fixed boundaries between the material and the immaterial in the experience of the built environment. Opting to adopt a performative-more specifically, pragmatist-approach, the authors propose to consider practice(d) ontologies to look for ontological alternatives. Ethnographic accounts are drawn from research on the experience of everyday mobilities in people moving into old age. The plot line first runs through memory works as boundary works, trying to understand how ghostly presence and material absence perform experience of (im)materiality. Second, it provides accounts of humans and nonhumans performing rhythms and suggests that rhythmic attunement involves boundary works. Performing a collective body by walking together is further considered as a case in point. Supported by the examples and the epistemological framework, the article suggests the versatile enactment of boundaries between body and world, that is, between the material and the immaterial.