Rigid polyurethane foam and laminate articles comprising a facing material and the said polyurethane foam are prepared by contacting under reaction conditions a urethane-modified polyisocyanate with a polyahl in the presence of a blowing agent comprising water. The urethane-modified polyisocyanate has an isocyanate content of from about 10 to about 29 weight percent and is obtained by reacting a polymethylene polyphenylisocyanate with a polyether polyol having a molecular weight of at least 2000 and an oxyethylene content of at least 35 weight percent. Use of this polyisocyanate provides for enhanced adhesion of the resulting foam, especialIy when it is an all-water blown foam, to facing materials such as metal.