Dorchester County, SC Building Setbacks & Zoning: Lot Coverage Limits (2026)

Section 7.1.6, Maximum Impervious Surface, governs the SR, Suburban Residential district, the county's lowest-density suburban district. It sets two caps: "(a) For non-residential uses in the SR district, no more than 30% of the gross acreage of a parcel shall be covered by impervious surface," and "(b) For single-family detached use in the SR district, no more than 50% of the gross acreage of a parcel may be covered by impervious surface." The section adds that these limits "may be superseded by specific development guidelines adopted by Dorchester County," and that except for residential subdivisions spanning multiple parcels, the cap "shall apply to the development as a whole" rather than lot by lot.

The equivalent section for the higher-density R-2 and R-2(M) districts, Section 7.3.7, allows more coverage: 40% for non-residential uses and 60% "for single-family detached and manufactured housing uses." Each of the county's zoning districts carries its own numbered Maximum Impervious Surface subsection, so the applicable cap depends on the parcel's zoning district, not a single countywide number. Impervious surface as used in these sections covers the building footprint plus driveways, parking areas and other surfaces water cannot penetrate, measured against the parcel's gross acreage. A property owner planning an addition, detached garage, pool deck or expanded driveway needs to check the impervious-surface subsection for the parcel's specific district before applying for a zoning permit, since exceeding the cap blocks issuance regardless of whether setbacks and lot-width minimums are otherwise met.