The present invention is directed an expandable, non-sagging polyurethane composition prepared by mixing: a liquid polysocyanate with a liquid isocyanate reactive mixture. The isocyanate reactive mixture comprises i) one or more hydroxyl group containing compounds containing from 2 to 8 hydroxyl groups and having molecular weights of from about 1000 to about 6000, ii) one or more low molecular weight diols or triols having hydroxyl equivalent weights of about 200 or less, iii) one or more organic di- or polyamines, and iv) a relatively small amount of water.