Abstract: The equations governing wind-induced internal pressure responses for a two-compartment building when the roof responds in dynamic and quasi-static manner are derived based on some reasonable assumptions. The gain functions, power spectra and RMS of internal pressures coefficients in both compartments calculated from the dynamic and quasi-static models are analyzed by the numerical example. The results show that the dynamic model must be used to calculate the response of internal pressure when the roof is flexible, otherwise, the simplified quasi-static model can be applied; with increased natural frequency of the roof, all the three resonance frequencies of the "internal pressure-roof" system increase, and the peak internal pressure responses at the first two frequencies also increase, while it decreases at the third resonance frequency. In addition, the RMS internal pressure coefficients obtained from both models also increase, but their difference decreases.