The demountable structure 1 comprises a framework 4 comprising parts secured together by manually-operable first fasteners, one or more side walls 3 defined by sheeting 27, 28 and stretched taut within the framework by manually-adjustable second fasteners. The structure may have a base frame 5, an upper frame and adjustable feet 9 to vary the height of the base frame relative to the floor. The first fasteners may comprise antiluce fasteners or lock pins, and the frames may be of identical polygonal shape. The base frame may be covered by a baseboard which is upholstered or provided with a mattress. The second fasteners may comprise straps with buckles, and the walls may be a one-piece construction. The structure may have manually-operable third fasteners which are zips 37, 42, one half of the zip secured to the framework and the other to the sheeting. The structure may comprise a detachable roof, a zipped doorflap and padding located on the inside.
