Abstract: A solarium includes window panel frames for supporting a plurality of window panels. Each window panel frame comprises a set of frame members defining a first surface, a diametrically opposed second surface, and a pair of third surfaces extending therebetween. The third surfaces define a third surface connecting recess positioned adjacent their corresponding intersection with the first surfaces. The window panels are made of thin and flexible sheets of material, such as heat shrinkable polymeric resin. A panel locking component is attached to the marginal edges of the window panels. The panels are undersized relative to the window frames when not mounted thereto, are secured to the window panel frame using the panel locking components, and then heat shrunk to a tensed state.