Purpose Building operation and maintenance (BOM) services are important activities for highly competitive businesses. In addition, outsourcing decision factors are key to the effectiveness of BOM. Hence, the purpose of this paper is to identify and prioritize the decision factors that affect outsourcing decision factors for BOM services, to elicit the different perceptions of each managerial group (shopping centers, hotels, and hospitals), and to categorize the important outsourced BOM decision factors. Design/methodology/approach On the basis of the literature review, the authors observed that there are 56 outsourcing decision factors in six groups. The survey included 105 of the largest and most competitive companies in Bangkok, Thailand. The statistical methods applied were the relative importance index (RII), t-test, one-way analysis of variance (ANOVA), and factor analysis (FA). Findings The findings show that the three participant groups are different in some respects, as shown by their RII values. After ranking the RII values, the top 15 factors for each participant group were used to compare the participant groups using the t-test and one-way ANOVA, which confirmed their respective similarities and differences. Through an FA, the top reasons that each business outsourced BOM services were grouped into major categories. Originality/value The results of this research will not only facilitate an understanding of the related decision factors used by each particular business in the commercial sector but will also assist outsourcing companies in identifying and improving support services for businesses.