The LBNL Residential Diagnostics Database (ResDB) contains blower door measurements and other diagnostic test results for US homes. Most of the data have been contributed by weatherization assistance programs and residential energy efficiency programs. We analyzed the air leakage measurements, using normalized leakage as the metric, of 134,000 single-family detached homes. Almost all 50 US states are represented.We performed regression analyses to examine the relationship between normalized leakage and various house characteristics. We identified parameters that are useful as explanatory variables, including floor area, height, vintage, and climate zone. Foundation type and whether ducts are located outside or inside the conditioned space also were found to be useful parameters for predicting normalized leakage. We developed a Table of Contents ABSTRACT .