Abstract: The present paper discusses the room transfer function method used for heavy constructructions. The comparisons show that the three-term weight factors precalculated for typic building rooms should not be used for heavy coostructions, even if the five-term weight factors might result in the error of load calculation more than 10%. Five-term weight factors produced by more than five equations and the weight factors above five terms may greatly improve the accuracy of load calculation and extend the use of room transfer function.