A portable shelter includes one or more floor panels, a plurality of exterior wall panels, and one or more roof panels. Each of the floor panels defines a plurality of floor panel apertures. Each of the exterior wall panels has a first wall flange that abuts a floor panel from among the one or more floor panels and defines a plurality of first flange apertures that align with the plurality of floor panel apertures of the floor panel. Each of the floor, exterior wall, and roof panels includes a foam core and two fiberglass sheets sandwiching the foam core. A plurality of threaded fasteners may be inserted through the one or more floor panels and the flanges of the plurality of exterior wall panels via the aligned pluralities of apertures.