One of the barriers to implementing high-performance building strategies is the lack of available information for labor costs. Without more information on the costs to build the new assemblies, many builders, architects and homeowners will remain with code-built structures. This session will present multiple perspectives from experienced practitioners on how they estimate retrofit and new construction high-performance assemblies.  Each of the four speakers will present one single-family project with cost data, how they estimated the costs, how these compared with actual costs, and what lessons they learned from the process of building something new. Learning from the mistakes others have made is a value the NESEA community promotes. This is an opportunity to learn from experienced builders’ estimating mistakes.