An apparatus and method for producing a continuous slab of polymeric foam uses an open topped trough with an upper pour plate adjacent to a moving conveyor. A liquid reactant foam mixture is continually introduced into the bottom of the trough and allowed to rise and partially expand until the mixture flows over the pour plate and onto a moving conveyor to complete its expansion and cure as it is conveyed. The inner surfaces of the trough are chilled to reduce the reaction rate of the liquid foam mixture and thereby prevent the undesired build-up of cured foam on the surfaces of the trough. The chilled trough may be formed from a plurality of hollowed panels fitted with interior baffles to define inner fluid passageways. A chilled fluid, such as water, is pumped through the passageways. Longer production runs with fewer defects are advantages of this apparatus and method.