A concrete form block for construction of a building includes first and second panel devices, each having inner and outer faces separated by ribs. Projecting connectors are disposed on the inner faces and each has a pin-receiving aperture. U-shaped couplers are used to connect the two panel devices together so that their inner faces are parallel. Each connector has first and second connecting pins and these are received in the apertures of the connectors of the panel devices, with each pin being pivotable in its aperture after insertion. The panel devices can be moved from a collapsed configuration having at least a reduced space between the inner faces and an in-use configuration with more space between these faces. There is also disclosed a panel structure having upper and lower channel forming frames connected to an outer wall portion thereof. These form a channel for receiving equipment for utilities.