Location of air barrier in roof assembly

I have been mentally working on details for a future renovation and have a question about locating an air control layer in the roof assembly.My house is a 1920s semi-detached… I have been mentally working on details for a future renovation and have a question about locating an air control layer in the roof assembly.My house is a 1920s semi-detached…Read MoreGreenBuildingAdvisor