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Simpsonville, SC Accessory Structures: ADU Rules (2026)

Some Restrictions

Compiled from the official code textEditor Martyn O'NeillLast verified September 2026

ADU rules in Simpsonville, SC, also called accessory dwelling unit regulations or granny flat ordinances, cover setbacks, owner-occupancy, parking, and permit requirements.

Key Facts

Governing rule: Zoning Ord. Sec. 3.3.4
Where ADUs allowed: Above-ground floors, nonresidential bldgs
Backyard detached ADU: Not a by-right use
RV/mobile home as ADU: Prohibited
Same lot required: Yes, subordinate to principal use

ADU Eligibility Quick-Check

An Accessory Dwelling Unit (ADU) is a smaller, independent living unit on the same lot as a single-family home: converted garages, detached cottages, basement or attic conversions, and attached additions all qualify. Most states have streamlined ADU permitting since 2020, but local rules still control size, height, and setback.

Is your lot zoned single-family or multi-family residential?
Does your lot have at least 1,200 sq ft of buildable space?
Is your existing home owner-occupied (in most states this is not required, but some require it for ADU permits)?
Will the ADU stay under your state's size cap (commonly 850-1,200 sq ft for detached)?
Can you provide one off-street parking space (waived in many states within 0.5 mi of transit)?

If you answered 'yes' to most of these, you likely qualify in South Carolina under recent ADU streamlining laws. The Simpsonville, SC rules below cover local size, height, and setback requirements.

Summary

Simpsonville's Zoning Ordinance sharply limits ADUs. Under Section 3.3.4, an accessory dwelling unit may only be placed on stories above the ground floor of a nonresidential building (or in an approved live-work arrangement). There is no by-right detached backyard ADU/granny-flat allowance for single-family lots.

Except for appropriate live-work arrangements, accessory dwelling units may only be permitted on stories above the ground floor of nonresidential buildings.

View official code

Full Breakdown

Section 3.3.4 ("Dwelling, Accessory") governs ADUs. Unlike cities with liberal backyard-cottage rules, Simpsonville confines accessory dwellings to upper floors of nonresidential buildings and requires shared walls/floors between residential and nonresidential uses to be built to minimize noise and vibration transmission. Mobile homes, recreational vehicles, and travel trailers may never be used as accessory dwelling units (definitions section). All accessory uses must be subordinate to the principal use and located on the same lot. Because a detached backyard ADU is not a listed accessory use for single-family districts, homeowners wanting a rentable second unit should confirm district and use eligibility with the Planning Department before building.

Violations & Fines

Building or occupying an unpermitted dwelling violates the Zoning Ordinance; the City may withhold permits, issue stop-work orders, and require removal. Penalties follow Code section 1-9.

Frequently Asked Questions

Can I build a backyard granny flat in Simpsonville?

Not by right. Section 3.3.4 permits accessory dwelling units only above the ground floor of nonresidential buildings or in approved live-work arrangements. Confirm any exception with the Planning Department.

Can I rent out an RV or camper as a second unit?

No. The Zoning Ordinance states mobile homes, recreational vehicles, and travel trailers shall not be used as accessory dwelling units.

Sources & Official References

[1]City of Simpsonville Zoning Ordinance (2024)

Other rules in Simpsonville

Noise Ordinances: Construction HoursSome Restrictions Shed & Carport RulesSome Restrictions Tiny HomesSome Restrictions Garage ConversionsSome Restrictions Noise Ordinances: Barking DogsSome Restrictions Noise Ordinances: Amplified Music & Outdoor SoundSome Restrictions Noise Ordinances: Vehicle NoiseSome Restrictions Parking Rules: Abandoned VehiclesSome Restrictions Animal Ordinances: Wildlife FeedingSome Restrictions

All Simpsonville rules

How Simpsonville compares: Easiest Cities to Build an ADU·Compare Simpsonville to another location·View the South Carolina accessory structures overview

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