A coke oven includes an oven chamber configured to support and heat a coal bed, a castable slab below the oven chamber, and a foundation supporting the heat recovery oven. One or more beams are positioned between the castable slab and the foundation. The beams extend from a first end of the oven chamber to a second end of the oven chamber, forming a plurality of air gaps between the castable slab and the foundation. Heat from the oven chamber is dissipated by the one or more beams.