Insulation in Charleston County

Every jurisdiction we cover in Charleston County

Click a city for its full code, permit and rebate detail.

All 22 publish an energy code edition we could name and all 22 a required R-value we could read; a blank in this table means the jurisdiction publishes nothing, not that we guessed.

Why the city matters

South Carolina writes one residential energy code for the whole state, and under S.C. Code 6-10-40 a town may vary it only with the state Building Codes Council's approval, so the attic figure for new work is R-30 in every one of the 22 places we cover in Charleston County. What changes from town to town is the permit desk.

Here, Adams Run, Awendaw, Charleston, Unincorporated Charleston County, Edisto Island, Folly Beach, Hollywood and Johns Island require a permit for insulation work; Adams Run, Awendaw, Charleston, Unincorporated Charleston County, Edisto Island, Folly Beach, Isle of Palms and James Island require contractors to register. The town pages carry each department's number.

Town by town across Charleston County

• Adams Run — 234 homes, median built 1984, 10% before 1940; energy code: 2009 IECC (state law); attic R-30 for new work; permit to insulate: yes.
• Awendaw — 818 homes, median built 2001, 2% before 1940; energy code: 2009 IECC (state law); attic R-30 for new work; permit to insulate: yes.
• Charleston — 77,417 homes, median built 1995, 10% before 1940; energy code: 2009 IECC (state law); attic R-30 for new work; permit to insulate: yes.
• Unincorporated Charleston County — energy code: 2009 IECC (state law); attic R-30 for new work; permit to insulate: yes.
• Edisto Island — energy code: 2009 IECC (state law); attic R-30 for new work; permit to insulate: yes.
• Folly Beach — 2,221 homes, median built 1990, 3% before 1940; energy code: 2009 IECC (state law); attic R-30 for new work; permit to insulate: yes.
• Hollywood — 2,589 homes, median built 2003, 3% before 1940; energy code: 2009 IECC (state law); attic R-30 for new work; permit to insulate: yes.
• Isle of Palms — 4,588 homes, median built 1986, 0% before 1940; energy code: 2009 IECC (state law); attic R-30 for new work; permit to insulate: not published.
• James Island — 4,971 homes, median built 1970, 0% before 1940; energy code: 2009 IECC (state law); attic R-30 for new work; permit to insulate: not published.
• Johns Island — energy code: 2009 IECC (state law); attic R-30 for new work; permit to insulate: yes.
• Kiawah Island — 3,865 homes, median built 1989, 0% before 1940; energy code: 2009 IECC (state law); attic R-30 for new work; permit to insulate: yes.
• Lincolnville — 577 homes, median built 1987, 2% before 1940; energy code: 2009 IECC (state law); attic R-30 for new work; permit to insulate: not published.
• McClellanville — 357 homes, median built 1984, 15% before 1940; energy code: 2009 IECC (state law); attic R-30 for new work; permit to insulate: yes.
• Meggett — 739 homes, median built 1991, 9% before 1940; energy code: 2009 IECC (state law); attic R-30 for new work; permit to insulate: yes.
• Mount Pleasant — 44,376 homes, median built 2000, 1% before 1940; energy code: 2009 IECC (state law); attic R-30 for new work; permit to insulate: yes.
• North Charleston — 54,781 homes, median built 1996, 1% before 1940; energy code: 2009 IECC (state law); attic R-30 for new work; permit to insulate: not published.
• Ravenel — 1,063 homes, median built 1993, 1% before 1940; energy code: 2009 IECC (state law); attic R-30 for new work; permit to insulate: yes.
• Rockville — 71 homes, median built 1975, 7% before 1940; energy code: 2009 IECC (state law); attic R-30 for new work; permit to insulate: yes.
• Seabrook Island — 2,574 homes, median built 1988, 0% before 1940; energy code: 2009 IECC (state law); attic R-30 for new work; permit to insulate: yes.
• Sullivan's Island — 1,088 homes, median built 1981, 27% before 1940; energy code: 2009 IECC (state law); attic R-30 for new work; permit to insulate: yes.
• Wadmalaw Island — energy code: 2009 IECC (state law); attic R-30 for new work; permit to insulate: yes.
• West Ashley — energy code: 2009 IECC (state law); attic R-30 for new work; permit to insulate: yes.

What the towns publish across Charleston County

• Contractor registration: 21 of the 22 publish a requirement for contractors to register (Adams Run, Awendaw, Charleston, Unincorporated Charleston County, Edisto Island, Folly Beach, Isle of Palms, James Island, Johns Island and Kiawah Island).
• A permit rule for insulation: 18 of the 22 publish one (Adams Run, Awendaw, Charleston, Unincorporated Charleston County, Edisto Island, Folly Beach, Hollywood, Johns Island, Kiawah Island and McClellanville); the rest leave it to a call to the building department.
• Historic districts on record in 9 of the 22: Charleston (Charleston Historic District, Old and Historic District, Old City District and Charleston's French Quarter District); James Island (Secessionville Historic District and Mosquito Beach Historic District); McClellanville (McClellanville Historic District); Mount Pleasant (Mount Pleasant Historic District, Old Village Historic District and Phillips Community Historic District); North Charleston (Charleston Navy Yard Historic District, Charleston Navy Yard Officers' Quarters Historic District and Charleston Naval Hospital Historic District); Rockville (Rockville Historic District).

The 17 places here with their own Census row hold 202,329 of Charleston County's 209,803 homes (96%); the rest are in other municipalities or unincorporated areas.

Homes across Charleston County: the Census numbers

Charleston County has 209,803 homes in the Census count, with a median year built of 1991. 34% were built before 1980 and 39% in 2000 or later; the single biggest decade was the 2010s, with 37,713 homes (18%). Of 178,975 occupied homes, 20% heat with utility gas and 76% with electricity.

Across the 17 places we cover here, Sullivan's Island has the oldest housing (27% before 1940) and Hollywood the newest (58% built in 2000 or later). Charleston is the largest, at 77,417 homes, and Ravenel has the most electric heat (93%).

Against the three-county metro on this site (378,268 homes), Charleston County's pre-1940 share of 5% compares with 3%, and its electric-heat share of 76% with 76%. 4,426 occupied homes (2%) burn propane or other tank gas and 257 (0%) heat with wood, which matters because neither fuel comes with a gas utility's program attached. 64% of occupied homes are owner-occupied and 58% of all homes are single-family detached houses.

In Charleston County that adds up to 54,828 homes from the 1950s to the 1970s, the usual candidates for an attic top-up; 81,032 built since 2000, where air sealing tends to matter more than extra depth.

Figures: U.S. Census Bureau, American Community Survey 2020–2024 5-year estimates (tables B25001, B25003, B25024, B25034, B25035, B25040). Survey estimates carry margins of error, widest in the smallest places. Census table.

What the rebate picture looks like in Charleston County

Homes across Charleston County buy electricity from Dominion Energy South Carolina and Berkeley Electric Cooperative, and the name on the bill decides which program applies. For Dominion Energy South Carolina customers with electric heat, Home Energy Check-up Plus covers 90% of the cost of attic insulation, air sealing and duct sealing, with a ceiling of $2,880, on jobs completed by March 31, 2027 after the free Home Energy Check-up; the program's own contractor does that work, not us.

Berkeley Electric lends rather than rebates: its HomeAdvantage program lends up to $20,000 at 5%, with an energy audit first and the payments added to the electric bill. Income-qualified households can apply to Palmetto Community Action Partnership (843-720-5336) for free weatherization instead. Every condition attached is in the rebate guide.

Common questions across Charleston County

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