In many inner-city neighborhoods existing infrastructure needs to be repaired, replaced, or modernized to serve both new and existing development. If the developer is forced to pay for these upgrades, the project may not pencil out. Regulatory burdens are high. Infill tends to be more heavily regulated than new development in newly developing places. Sometimes infill requires rezoning.
Building codes can be unrealistic for rehabilitation projects.
Restrictions on use can limit the types of units that can be developed. Existing neighborhood groups can feel threatened by infill. The ability of these groups to participate in and slow down the regulatory process increases the time it takes to complete an infill project, raising costs. Questions concerning safety and school quality discourage many people from infill housing. Urban areas are perceived by many people to be less safe than the suburbs.