Urethane foam virtually seals surfaces so there is very little possibility for water vapor to pass through it thus preventing problems like condensation which can lead to mold and mildew. Urethane foam acts as its own effective vapor, water and wind barrier. When installed, urethane foam adds to the value of your building because it has the highest R-value per inch than any other insulation product available. It also adds structural stability. When considering a product to insulate your building think of urethane foam as an investment not as a cost.