This article examines the optimization method for the timber-framed houses ally regarding the rain leaking caused by the inappropriate construction. Using the database of 6000 cases obtained by the dwelling inspection of 11 years, the rain leaking and condensation cases are extracted and categorized into the region and construction method. Having a questionnaire survey, 35 cases became the comparative analysis data for the inappropriate construction. As the result increase of multi function worker against to mono function worker are often to be the cause of inappropriate construction because of the shortage of experiences and literacy for vocational ability and domain.
