Permit records from the City of Seattle permitting system for building permits that create or demolish housing units. Records begin in 1990 and are through the current year quarter.The permits in this layer are those that are currently issued. This data does not contain records for those permits that were issued but were not completed, cancelled or withdrawn.Each record represents the number of units added or demolished for each housing type in the project. Therefore a single building permit may appear multiple times if there are a mix of unit types in the project.Housing unit types reflect the unit types regulated by the building codes and change through time. There has been no attempt to standardize these types and therefore reflect the unit types that existed at the time the permit was issued.There may be multiple permits at any given address.