InterSections/Borden/1 Iain Borden Thick Edge: Architectural Boundaries in the Postmodern Metropolis Based on the chapter in: Iain Borden and Jane Rendell (eds.) InterSections: Architectural History and Critical Theory, (2001) pp. 221-46. ____________________________________________________________________ Boundaries present themselves to us as the edge of things, as the spatial and temporal limit between the here and there, in and out, present and future. The boundary in all its manifest forms – wall, façade, gate, fence, river, shore, window – appears as a discrete separation between alternate sides of its magical divide; things are dispersed and ordered in space. 1 Yet for postmodern urban space, in which architects assay the wrapping and layering of space, and urban managers increasingly review its representation and control, nothing could be farther than the truth; boundaries are not finite, but zones of negotiation. The more thoughtful theoreticians of architecture have always understood buildings as possessing this kind of boundary-negotiation when considering the mechancial and servicing elements. [T]he array of different reservoirs in buildings is defined by a multitude of boundaries . These boundaries may be the metal pipes and ducts of servicing systems; they may perhaps be the different material boundaries to damp air passages in lofts; they may also be the faces of masonry walls, where the solid material acts as reservoir for heat energy; and they may be defined by material content: timber has to have a moisture content (MC) above 20% to support fungi, so that the MC level in effect becomes a boundary to fungal action. There are also grain boundaries. 2 They are also aware of the differential nature of boundary effects. Some boundaries are opaque to one entity, but transparent or permeable to another (i.e. semi-permeable): dry rot or radon can pass through brickwork, whereas pet budgerigars cannot. 3