This paper reports on field hygrothermal performance of white full-vent perforated soffit and ceiling compared to common wood soffit and gypsum ceiling. Testing was conducted using a two-story residential house located in Bangkok of 100 m(2) floor surface area. Data collection included ambient conditions, attic temperatures at various positions, and relative humidity of air in the bathroom and in the attic measured at 30 cm. above the ceiling. Experimental results pointed out that perforated ceiling is very effective for reducing attic air temperature and moisture in the bathroom. Due to the solar radiation during daytime, the induced stack ventilation decreased heat and moisture accumulations in the bathroom and the attic. Such performance is extremely significant when compared to the performance of the original ceiling (gypsum board) where moisture removal by a small window took much longer time to achieve the same level of performance. After sunset, the temperatures at all positions in the attic were very close to ambient, which is an additional advantage for energy saving and comfort. Therefore, it is expected that perforated soffit and ceiling will be quickly integrated in the new design of modem houses as a new interesting option that promotes passive moisture ventilation and attic heat gain reduction. (c) 2005 Elsevier Ltd. All rights reserved.