Urethane foam has been used to insulate the outside of the peripheral building columns of Columbia Broadcasting System's 38 story office building in Manhattan. The triangular columns are integral with the reinforced concrete floor slabs. Because the columns present two sides to the weather, excessive expansion and contraction under extreme weather conditions might cause floor cracks. The foam was applied by the system of hoses and pipes to a depth of about 6 feet at one application. Curing time was about 5 minutes. The hosing reached three floors. Within these limits there was as many applications of the foam as was convenient. In comparison with rigid board insulation, urethane foam required less scaffolding and no dampproof coating. Urethane foam expands to 32 times the volume of its components, or in terms of hoist time one hoist load of urethane components is equal to 31 hoist loads of prefoamed insulation.