Abstract: A polycarbodiimide-polyisocyanurate foam is prepared by reacting(A) mixture of a polyol blend comprising(a) 25 to 100% of an aromatic polyester polyol having the following structure: ##STR1## where n=1, 2, or 3 and having hydroxyl number 150 to 330, (b) 0 to 35% of a flexible polyether polyol with hydroxyl number 20 to 70,(c) 0 to 25% of a toluene diamine ethoxylated polyol, optionally with some propoxylate, and having hydroxyl number 330 to 480,(d) 0 to 25% of a nonyl phenol ethoxylate and having hydroxyl number 70 to9 150, andwith surfactant, catalyst, and water; and reacting with(B) a polyphenyl polymethylene polyisocyanate such that the mixture of A is reacted with B at a 1:1 by volume mix ratio.