Wind-induced internal pressures in houses

The effects of ten different opening configurations on the internal pressures in a typical two-story North American house were examined using volume-scaled, wind tunnel experiments. The configurations examined include the effects of (1) dominant opening locations and sizes; (2) wall leakage; (3) compartmentalization of the attic space from the living space; and (4) roof and soffit vents. Helmholtz resonance was observed to significantly amplify the internal pressures for open area ratios greater than 3% and full-scale volumes of approximately 700 m(3). The ASCE 7-05 was found to significantly underestimate the peak internal pressure coefficients for all configurations with dominant openings, regardless of whether there was significant Helmholtz resonance or not. Peak external roof pressures were observed to be highly correlated in time with the internal pressures. It is shown that sealing the attic space from the main (living) space of the house has a significant benefit in not allowing the internal pressure to act on the underside of roof sheathing. However, for just 0.4% open area between the two spaces, peak pressures of 80% of the peak in the living space are transmitted into the attic.