This proposed addendum adds new definitions, revises Sections 6 and 7, and adds a new Section 8 with requirements specific to multifamily buildings. The proposed changes to requirements account for unique features of multifamily buildings compared to single-family buildings and include adjusting the whole building ventilation rate due to the fact that infiltration cannot be relied on for individual units in multifamily buildings, provision of ventilation to common spaces and common parking garages which do not exist in single-family buildings, and prevention of contaminant transfer from other units through walls or ducts.