Planning Commission workshop: staff says current zoning likely yields about 70,000 homes over 10 years while demand models point to far higher need

At a Planning Commission workshop, planning staff presented an update on a countywide housing and infrastructure study and said current zoning and market patterns likely would yield roughly 70,000 new housing units over the next 10 years while the study’s demand model indicates about 90,000 units may be needed.

The study, framed around three themes—abundant housing, necessary infrastructure and distinctive communities—aims to compare projected housing demand with how much the existing zoning map and building rules are likely to produce and to identify where and what types of code changes and infrastructure investments would narrow any gap.

Greg Claxton, Planning Department staff, described the project’s methods and findings, saying staff combined local permitting data, parcel characteristics and probability modeling to estimate realistic build-out under current rules. Claxton said the team used two standard forecasts (the state data center at the Boyd Center at the University of Tennessee and Woods & Poole) and a custom Unified Housing Strategy (UHS) forecast to test demand scenarios. He said the UHS estimate “is in line with the other looks that we’ve had” and that the UHS demand estimate is about 90,000 units over 10 years.

Claxton told commissioners the team modeled every parcel in the county using the last 10 years of permitting activity to estimate both how many units a parcel could physically support and the likelihood that a parcel would redevelop. That probability-weighted approach, he said, produces a different and lower estimate of likely production than a pure capacity calculation. Using that method, staff estimated about 70,000 units are likely under the current zoning map over the next decade.

Staff also described uncertainty and a recommended buffer. Claxton said growth rates, household formation patterns and other variables could push demand higher or lower and that the team plans to include a buffer to reflect that uncertainty; he said that buffer might be in the range of 15,000 to 25,000 additional units and that staff is “wanting to be ready for 110, 120,000 units.”

Commissioners asked for clarifications on methods and policy tools. In response to a question about the model’s fractional results, Claxton explained the model can show partial-unit averages where several small parcels are likely to be combined and redeveloped into multiple units; he used the example of three small lots bought by a single developer and replaced by five units to explain a “half unit” or fractional-unit result.

On affordability, staff noted a new state-authorized tool—often described in the meeting as an “affordability bonus”—that would allow a developer to gain additional development entitlement (for example, an extra story) in exchange for providing income-restricted units. Claxton said the tool is newly enabled by state law, would be tested with market feasibility work and is likely to be implemented at the building-permit stage rather than as a condition on rezoning. He said legal review is required and that retroactive application would present legal difficulties.

The presentation also highlighted infrastructure constraints that affect where housing can realistically be added. Claxton emphasized street connectivity, water, sewer, stormwater management and fire service proximity as critical infrastructure considerations. He showed examples where stub streets, ownership gaps or topography block the creation of a connected street network and said those constraints reduce the likelihood that parcels zoned for multifamily along corridors will actually redevelop as housing.

Claxton said process differences matter: subdivision reviews or planned developments (SPs) can secure street connections and other public improvements, but building permits that proceed through the front counter typically do not create the same leverage to require off-site connections. He said staff is coordinating with finance and other Metro offices to identify critical segments for acquisition or capital budgeting to enable future housing on targeted corridors.

No formal actions or votes were taken at the workshop. Staff said the study will produce alternative zoning scenarios and financial-feasibility testing for new housing typologies (for example, cottage courts, triplexes and fourplexes), and that the results will inform future Commission deliberations and potential code amendments. The presentation also anticipates coordination with the Greater Nashville Regional Council’s regional transportation work and alignment with the Nashville Next policy framework.

Claxton closed by inviting commissioners to follow up with staff; commissioners and staff said they will continue work sessions as the team refines scenarios and tests affordability-bonus designs.

The workshop was informational; the Planning Commission scheduled a short break before the regular commission meeting.