A continuous process for the production of polyurethane block foam, in which the reactive components polyol and isocyanate are fed in metered amounts to a mixer and are mixed therein to form a polyurethane reaction mixture, and the polyurethane reaction mixture is applied to a conveyor belt and foamed and cured thereon, wherein a) after mixing, the polyurethane reaction mixture is discharged in free-flowing manner from the mixer through at least one outflow opening and flows through the feed opening into an accumulation chamber which is extended in the vertical direction and closed at the sides and which opens in the region of the base into a gap opening, and b) the polyurethane reaction mixture accumulates in the accumulation chamber so that static pressure is produced at the base of the accumulation chamber over the entire width, which is between 100 and 5,000 Pascal, and the polyurethane reaction mixture flows through the accumulation chamber from top to bottom, and c) the polyurethane reaction mixture then flows through the gap opening out of the accumulation chamber and flows through a gap, the underside of the gap being formed by a conveyor belt and the gap being closed at the top and bottom and at the lateral edges, and d) the polyurethane reaction mixture then flows from the gap into the expansion chamber and foams therein, the conveyor belt forming the underside of the expansion chamber, and wherein the expansion chamber being closed at the lateral edges, and the flow cross-section of the expansion chamber widening in the transport direction of the conveyor belt, and e) the foamed polyurethane reaction mixture leaves the expansion chamber through an outlet opening and cures on the conveyor belt, wherein the mean dwell time of the reaction mixture from emerging from the mixer to leaving the accumulation chamber through the gap opening is not more than 15 seconds. a) after mixing, the polyurethane reaction mixture is discharged in free-flowing manner from the mixer through at least one outflow opening and flows through the feed opening into an accumulation chamber which is extended in the vertical direction and closed at the sides and which opens in the region of the base into a gap opening, and b) the polyurethane reaction mixture accumulates in the accumulation chamber so that static pressure is produced at the base of the accumulation chamber over the entire width, which is between 100 and 5,000 Pascal, and the polyurethane reaction mixture flows through the accumulation chamber from top to bottom, and c) the polyurethane reaction mixture then flows through the gap opening out of the accumulation chamber and flows through a gap, the underside of the gap being formed by a conveyor belt and the gap being closed at the top and bottom and at the lateral edges, and d) the polyurethane reaction mixture then flows from the gap into the expansion chamber and foams therein, the conveyor belt forming the underside of the expansion chamber, and wherein the expansion chamber being closed at the lateral edges, and the flow cross-section of the expansion chamber widening in the transport direction of the conveyor belt, and e) the foamed polyurethane reaction mixture leaves the expansion chamber through an outlet opening and cures on the conveyor belt,