This paper quantifies carbon emissions due to on-site equipment use in the post-tensioned slab foundation construction process of production homes in Phoenix Arizona. The construction activities performed during post-tensioned slab foundation construction, trades/sub-trades/vendors and the list of construction equipment used for every activity are identified. Data collection involved field visits to several subdivisions, interviews with trades, quantification of use time and the fuel use rate for each equipment as well as the fuel type used for every construction activity. Emissions from fuel consumption were quantified using the guidelines provided by the U.S. Environmental Protection Agency. Analysis of emissions indicates that the concreting trade, the plumbing trade and the grading sub-trade are the three most significant trade components. Activities 'set floor', 'plumbing', 'pour floor' and 'backfill and grading' are the four most significant construction activities. Emissions of on-site equipment use are in the range of 4 to 15% of emissions due to transportation. This study is useful for home builders, trade contractors and vendors involved in production home building construction to measure emissions of on-site construction processes, identify significant construction activities and trade components and plan for improvement.