A top section for an oven formed with an outer support shell, an intermediate insulating layer and an inner refractory lining wherein the three layers are connected by a plurality of spaced members. The spaced members are preferably formed as stainless steel pegs welded to an inner surface of the outer support shell extending across the intermediate insulating layer and fixed to the inner refractory lining as a result of the cast refractory lining setting around the pegs. The pegs may be covered at least in part by a plastic tip or coating to provide a relative expansion capacity between the pegs and the refractory lining. The outer section is preferably formed from steel, may be any suitable shape and includes one or more apertures to form doorways, flues and access ports for accessory items such as char-grilles, lights, fire retardant systems and windows. The invention extends to an oven including a top section as disclosed. The invention also extends to a method of forming an oven comprising the steps of forming the outer housing, welding pegs to an inner surface of the outer housing, locating insulating material inside the outer housing, positioning a mold defining a cavity of the top section and pouring and setting a castable refractory lining of the oven. The method may further include the step of positioning plastic tips over the pegs.