Traditional zoning was developed during a time when factories and many commercial uses were noisy, smelly, and/or hazardous to the public. To protect public health and residential property values, early zoning focused on separating different uses and buffering them from each other to minimize nuisances.
Today, much commercial development is environmentally benign, and there are often advantages to locating different uses in close proximity. Mixed use concentrated development, preferably near transit, is seen as a key “smart growth” tool to reduce auto dependence and preserve green space and natural resources. Thus many communities are turning to “mixed use,” which generally refers to a deliberate mix of housing, civic uses, and commercial uses, including retail, restaurants, and offices.
Mixing uses, however, works best when it grows out of a thoughtful plan that emphasizes the connectivity and links among the uses. Results may be haphazard when communities simply enable multiple uses without providing guidance about the mix of uses and how they are spatially related.
To achieve well-planned mixed use development, what jurisdictions often implement are called “overlay” districts. This means that the underlying zoning remains in place. Developers may choose to develop according to the underlying zoning or, alternatively, according to the mixed use provisions. The overlay encourages coordinated, cohesive development among lots or through lot consolidation. The overlay approach is especially useful when the community wants to promote a unified approach in an area where there are two or more underlying districts.
If the community wants to encourage mixed use, the overlay should be structured to be attractive to developers and the requirements should not be onerous. The municipality typically retains control through the special permit process and can turn down any development not meeting its criteria. The role of the architect, of course, is to test out the municipality’s interpretation of its criteria and the public’s intent, and advocate for that result which best maps to the overlap between the regulatory environment vs. the developer’s need to realize a financially viable and responsible project.