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Beaufort County, SC Accessory Structures: ADU Rules (2026)

Q: How many accessory dwelling units can I build in Beaufort County?

One on a single-family lot under three acres, or two if the lot is three acres or larger, under Community Development Code § 4.2.30.C. Both counts apply only to legally permitted single-family detached residential lots.

Q: How big can a Beaufort County ADU be?

In T2 and conventional zones it must run between 300 and 1,000 heated square feet, and can never exceed the primary home's heated square footage. In every other transect zone, it has to be built as a carriage house under Section 5.1.40 instead of following that square-footage range.

Q: Can I rent my ADU out short-term?

Not for stays under 30 consecutive days unless you hold a Short-Term Rental Property (STRP) Permit under Division 4.1.360 and meet its permit, notice, and renewal requirements. Without that STRP Permit, an ADU can only be leased for terms of 30 consecutive days or longer, the same floor that applies to the principal home.

Some Restrictions

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

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

Key Facts

ADUs allowed, lots <3 acres: 1 unit
ADUs allowed, lots 3+ acres: 2 units
Size range, T2/conventional zones: 300 to 1,000 heated sq ft
Other transect zones: Must be a carriage house
Minimum stay if rented: 30 consecutive days
Resale: Cannot be sold apart from house

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 Beaufort County, SC rules below cover local size, height, and setback requirements.

Summary

Beaufort County allows one accessory dwelling unit on single-family lots under three acres and two on lots of three acres or more, capping each unit at 1,000 heated square feet in conventional zones under Community Development Code § 4.2.30, and barring resale or rental separate from the main house.

These county ordinances apply to unincorporated areas of Beaufort County. Incorporated cities within the county may have their own rules that take precedence over county-level regulations.

C.Density. Accessory Dwelling Unit(s) shall be permitted on a single-family residential lot as follows:1.One (1) Accessory/Secondary Dwelling Unit shall be permitted for lots less than three (3) acres.2.Two (2) Accessory/Secondary Dwelling Units shall be permitted for lots greater than or equal to three (3) acres.D.Area of Unit. In no instance shall the individual or combined total heated square footage of Accessory/Secondary Dwelling Unit(s) exceed the Primary Dwelling Unit's heated square footage.1.In T2 and all conventional zones, the unit shall be no more than 1,000 heated square feet or less than 300 heated square feet in area; or shall be within a carriage house building type, see Section 5.1.40 (Carriage House).

View official code

Official source re-checked September 7, 2026: no newer edition of the code had been published (publisher’s edition: Code of Ordinances: Supplement 55 Update 1 | Community Development Code: Supplement 16).

Full Breakdown

Beaufort County Community Development Code § 4.2.30, Accessory/Secondary Dwelling Unit, sets the countywide standard for ADUs on single-family lots in the unincorporated area. Density scales with lot size under § 4.2.30.C: one accessory dwelling unit is permitted on lots under three acres, and two are permitted on lots of three acres or more. The unit's heated square footage can never exceed the primary dwelling's heated square footage under § 4.2.30.D, and in T2 and conventional zones the unit itself must run between 300 and 1,000 heated square feet, or else be built as a carriage house under § 5.1.40.

In every transect zone besides T2, an ADU must be built within a carriage house building type. The unit has to match the architectural design, style, and character of the principal single-family home under § 4.2.30.E, and in conventional zones it needs one off-street parking space beyond what the primary house already provides under § 4.2.30.F. Beaufort County also blocks ADUs from becoming a separate real estate asset: § 4.2.30.G bars selling the unit apart from the principal dwelling on the same lot, and § 4.2.30.H bars leasing or renting it for stays under 30 consecutive days unless the owner has a Short-Term Rental Property (STRP) Permit under Division 4.1.360. Recreational vehicles and travel trailers can never be used as an ADU under § 4.2.30.I.

Violations & Fines

Building an ADU larger than 1,000 heated square feet in a conventional zone, adding a second unit on a lot under three acres, or selling the ADU separately from the main house all violate § 4.2.30, and renting the unit short-term without an STRP Permit exposes the owner to the county's short-term rental enforcement under § 4.1.360.E.

Frequently Asked Questions

How many accessory dwelling units can I build in Beaufort County?

One on a single-family lot under three acres, or two if the lot is three acres or larger, under Community Development Code § 4.2.30.C. Both counts apply only to legally permitted single-family detached residential lots.

How big can a Beaufort County ADU be?

In T2 and conventional zones it must run between 300 and 1,000 heated square feet, and can never exceed the primary home's heated square footage. In every other transect zone, it has to be built as a carriage house under Section 5.1.40 instead of following that square-footage range.

Can I rent my ADU out short-term?

Not for stays under 30 consecutive days unless you hold a Short-Term Rental Property (STRP) Permit under Division 4.1.360 and meet its permit, notice, and renewal requirements. Without that STRP Permit, an ADU can only be leased for terms of 30 consecutive days or longer, the same floor that applies to the principal home.

Sources & Official References

[1]Beaufort County Community Development Code § 4.2.30

Other rules in Beaufort County

Parking Rules: Street Parking LimitsSome Restrictions Fence Regulations: Height LimitsSome Restrictions Shed & Carport RulesSome Restrictions ADU Rental RestrictionsSignificant Restrictions Parking Rules: Driveway RulesSome Restrictions Parking Rules: Commercial & Oversized VehiclesSignificant Restrictions Fence Regulations: Neighbor Fence RulesSome Restrictions Fence Regulations: Material RestrictionsSignificant Restrictions

All Beaufort County rules

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