Permitted, Conditional, and Accessory Uses
Summary
Zoning sorts each use in a district as permitted by right, conditional (special) with a discretionary permit, accessory to a principal use, or prohibited. The category decides the approval path, the schedule, and the risk of conditions, so identify it for every use in the program before design begins.
Cols
Scope
- Use categories and their definitions are set by each local ordinance. Always verify the municipal code's definitions and the current zoning for the project parcel
- Covers the common categories, how they differ from variances, and the approval paths each implies
- Dimensional limits are in their own notes; building code occupancy is in the IBC notes
Terminology
- Permitted use (by-right use): a use listed as allowed in the district that needs no extra discretionary approval
- Conditional use (special use, special exception use): a use listed as allowed only after a permit and review
- Accessory use: a use customarily incidental to and subordinate to the principal use on the same lot
- Principal use: the primary use of a lot
- Prohibited use: a use not allowed in the district, whether listed or unlisted
- Temporary use: a short-term use such as a seasonal sale or construction office
- Home occupation: a business use within a dwelling, regulated as an accessory use
- Conditions of approval: requirements added to a conditional permit, such as hours, buffering, or parking
- Use variance: relief that allows an otherwise prohibited use; different from a conditional use
- Compatibility finding: a determination that the use fits with surrounding areas and permitted developments
Classification
Categories
| Category | Approval | Typical examples |
|---|---|---|
| Permitted by right | Zoning check at permit review; no hearing | Single-family house in a residential district |
| Conditional or special | Application, review, usually a public hearing, discretionary decision with conditions | Church in a residential area, larger restaurant, school |
| Accessory | Allowed with the principal use if it meets size and location limits | Garage, shed, home office, accessory dwelling unit |
| Temporary | Short-term permit | Construction trailer, seasonal stand |
| Prohibited | Not allowed unless the ordinance changes or a use variance is granted | Heavy industry in a residential district |
Conditional use review
- The permit is meant to let the zoning authority judge whether a use would disrupt the zoning scheme because of its location
- The standard enabling act permits such permits on a finding that the use is compatible with surrounding areas and with developments already permitted
- Review usually includes an application, staff report, public hearing, findings, and conditions
- Conditional use is not a variance: it is a use the ordinance has already listed as potentially acceptable, while a variance relaxes a requirement for hardship
- Expansion of a nonconforming use is sometimes handled as a conditional use
Requirements
Accessory uses
- An accessory use must be incidental and subordinate to the principal use on the same lot
- Ordinances limit accessory structures by height, size, number, and location, often by a percentage of the lot or of the principal building area
- Accessory dwelling units, detached garages, sheds, and home occupations each have their own standards in most ordinances
- An accessory structure may count toward lot coverage and floor area ratio
Unlisted uses
- Many ordinances treat unlisted uses as prohibited unless the zoning official classifies them as similar to a listed use
- A request for an interpretation or text amendment is the way to address a use that fits no category
Worked examples
Program check
A mixed-use project in a district with the use categories below.
| Use | Category in the district | Approval path |
|---|---|---|
| Apartments, 24 units | Permitted | Site plan and building permit |
| Ground-floor retail | Permitted | Site plan and building permit |
| Restaurant with bar | Conditional | Conditional use permit with a public hearing |
| Detached storage building | Accessory | Allowed if within size and location limits |
| Impact | Result |
|---|---|
| Schedule | The conditional restaurant sets the critical path, adding hearing and notice time |
| Option | Move the restaurant to a permitted use (retail, office) or seek a different district |
| Risk | The permit may carry conditions on hours, noise, parking, and outdoor seating |
Accessory structure
A detached garage on a lot with a 30 ft by 24 ft footprint is proposed beside a house.
| Step | Check | Result |
|---|---|---|
| Category | Customarily incidental and subordinate | Accessory use |
| Size | 720 sq ft against the accessory area limit in the ordinance | Compare with the limit |
| Location | Rear yard and side setback of the accessory standards | Often a smaller setback than the house |
| Coverage | Counts toward lot coverage and floor area ratio | Add to totals |
Coordination
- Client program: list every use, including accessory and outdoor uses, and map them to the use table
- Planning staff: pre-application meetings clarify whether a use is permitted, conditional, or needs an interpretation
- Schedule: build conditional use time into the project schedule; hearings fix dates
- Neighbors: notice requirements and neighbor concerns shape conditions; prepare drawings and operational statements
- Building code: classify occupancy for each use, since a conditional use may trigger a different occupancy group, parking, and sprinklers
- Future uses: a change of tenant to a conditional use may need new approval
Common issues
- Assuming a similar use is permitted: a restaurant and a bar can be different categories
- Accessory use grown too large: a storage building used as a shop may become a principal use
- Conditions late: conditions change building layout, such as buffers or hours, so learn them before drawings
- Conditional use runs with the use: many permits lapse or restrict changes of operation
- Use variance confusion: a use variance is a heavier, less certain path than a conditional use
- Unlisted use: treated as prohibited unless classified
Standards
- Local zoning ordinance: the use table and definitions
- Standard State Zoning Enabling Act: the basis for compatibility findings on special uses
Sources
- Wikipedia: Special-use permit, https://en.wikipedia.org/wiki/Conditional-use_permit
- Wikipedia: Variance (land use), https://en.wikipedia.org/wiki/Variance_(land_use)
- Wikipedia: Nonconforming use, https://en.wikipedia.org/wiki/Nonconforming_use