Abstract: A building panel, comprising a concrete portion with an inner and outer face, and an enclosing boundary portion around the inner face perimeter, with a rigid planar plastic sheet against the inner face, and spacing studs against the outer face, the studs including fasteners protruding through to embed into the concrete. Also, a method of forming the building panel comprising the steps of forming an enclosed-perimeter outer framework, positioning a plurality of spacing studs which include fasteners extending upwards within the outer framework, placing a planar plastic panel within the frame over the top of the studs with the fastening members protruding through, then pouring concrete into the frame to cover the panel, and fill the framework to the required depth, then removing the outer frame from the cured concrete.