Correlation of internal and external pressures and net pressure factors for cladding design

Net pressures on roofs and walls of buildings are dependent on the internal and external pressure fluctuations. The variation of internal and external pressures are influenced by the size and location of the openings. The correlation of external and internal pressure influences the net pressures acting on cladding on different parts of the roof and walls. The peak internal and peak external pressures do not occur simultaneously, therefore, a reduction can be applied to the peak internal and external pressures to obtain a peak net pressure for cladding design. A 1:200 scale wind tunnel model study was conducted to determine the correlations of external and internal pressures and effective reduction to net pressures (i.e., net pressure factors, 𝐹𝐶) for roof and wall cladding. The results show that external and internal pressures on the windward roof and wall edges are well correlated. The largest 𝐶𝑝̌,𝑛𝑒𝑡, highest correlation coefficient and the highest 𝐹𝐶 are obtained for different wind directions within 90