ABSTRACT
Floor systems may be exposed upward where the enclosure of a second level steps back to create an outdoor terrace on top of the first. Exposed floor assemblies require careful consideration of the barriers, in position and detail. Insulated concrete slabs on grade can take the place of framed floors. Slabs can also be cast inside a perimeter footing, bearing only the floor loads and no superimposed walls or columns. Particular care must be taken when floor systems are directly exposed to the exterior over a significant area. Framed floors at the first level become the thermal envelope of the building when they are suspended uncontrolled or partially controlled crawl spaces. The upper-floor wood framing is hung from the balloon framed walls with a continuous ledger to minimize thermal bridging and provide a full cavity for insulation. The subfloor is tongue-and-groove fir, originally covered by linoleum and oak flooring.
