Insulation and air sealing for Sullivan's Island homes: attics, crawl spaces, rim joists and walls, starting with a free assessment of the R-value you actually have. The typical home here dates to the early-1980s, and 27% of its 1,088 homes went up before 1940.
Sullivan's Island runs to about 2.5 square miles and roughly 2,087 people. It sits about 6 miles east of downtown Charleston. There are around 1,088 housing units here. The community dates back to 1975. We cover ZIP code 29482.
We have not logged a completed job in Sullivan's Island yet. We would rather say so than put a number on this page that is not real.
The typical home in Sullivan's Island dates to around the early-1980s. Houses of this vintage usually got batts or blown fiber at whatever the standard of the day was, which is well short of what is recommended now. Most are one top-up away from being right.
Mostly one- to two-story frame island houses and cottages from about 1880 to 1950 on raised pier foundations, plus former Fort Moultrie officers' quarters sold to private owners after 1947 and larger homes built since Hurricane Hugo.
That includes Moultrieville and Atlanticville. Housing age and construction shift across Sullivan's Island, sometimes by decades within a few streets, which is why we look in the attic before quoting rather than after.
Sullivan's Island sits at the mouth of Charleston Harbor, home of Fort Moultrie, and grew as a summer resort for Charleston. Its traditional 'island houses' are frame cottages built with porches to catch the ocean breeze, many raised on brick or wood piers to stand above high water, and storms have kept the island in a cycle of building and rebuilding. After Hurricane Hugo in 1989 many small island houses were replaced with much larger modern homes.
The Census Bureau estimates 1,088 homes in Sullivan's Island. 297 of them (27%) went up before 1940 — the highest share of pre-1940 housing among the 28 places on this site. More of today's homes date from before 1940 than from any single decade since, and 49% predate 1980. For Charleston County as a whole the pre-1940 share is 5%, so Sullivan's Island sits above it.
Of 798 occupied homes, 5% heat with utility gas and 81% with electricity; another 13% burn propane or other tank gas. Electric heat here is more common than across the county (76%), and ranks 13th of 28 on this site. Whoever comes out will ask about the furnace or heat pump first, since the heating fuel and the utility named on the bill settle which program money is on the table.
85% of occupied homes are owner-occupied and 90% of all homes are single-family detached houses. Read together, those numbers point toward wall insulation for walls built empty, a vermiculite check before anything is disturbed and an energy assessment before deciding what to fix first.
| Built | Homes | Share | |
|---|---|---|---|
| Before 1940 | 297 | 27% | |
| 1940s | 39 | 4% | |
| 1950s | 63 | 6% | |
| 1960s | 43 | 4% | |
| 1970s | 96 | 9% | |
| 1980s | 96 | 9% | |
| 1990s | 170 | 16% | |
| 2000s | 117 | 11% | |
| 2010s | 122 | 11% | |
| 2020 or later | 45 | 4% |
1,088 homes, Census ACS 2020–2024 (B25034, B25040, B25003); 798 occupied.
266 of Sullivan's Island's 1,088 homes (24%) were built in the 1980s and 1990s. The gaps in houses of that age are the parts nobody sealed: batts stuffed into the rim joist, bare spots over cathedral and tray ceilings, soffit vents buried with no baffles, can lights punched through the ceiling plane. A top-up plus a day of sealing usually covers it.
Sullivan's Island enforces the South Carolina Energy Standard (the 2009 IECC), by state law. The town says it follows the codes the South Carolina Building Codes Council adopts, although its own codes page still shows the 2018 editions; for insulation that changes nothing, because the 2009 energy standard comes from state law.
For new work, the attic number under that edition is R-30, with walls at R-13. Set that against the Department of Energy, which recommends R49 for an uninsulated attic in this climate zone and R38 for one that already has a few inches.
Table 402.1.1 of the 2009 IECC, climate zone 3, which South Carolina's Energy Standard Act adopts for the whole state (section 6-10-30 of the South Carolina Code).
Sullivan's Island requires a permit for this work. The Town says "building permits are required by law for any repair or improvements to a residential or business property," and its permit-requirements page adds that this covers all additions, repairs and remodeling. The Town's standard inspection list includes an insulation inspection. Its rule of thumb: if you don't know, call the Building Official. We pull it as part of the job.
The published number is 843-883-5732. The department page is here.
Permitting is on us, not on you.
Berkeley Electric Cooperative's own territory map shows none of its service inside Sullivan's Island; the other electric utility on record for Charleston County is Dominion Energy South Carolina. 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.
Income-qualified households can apply to Palmetto Community Action Partnership (843-720-5336) for free weatherization instead. Every condition attached is on the Charleston County page and in the rebate guide.
Every layer of an insulated attic, explained
Sullivan's Island borders Mount Pleasant, Isle of Palms, Charleston Harbor, Breach Inlet and Intracoastal Waterway. These are the ones we also cover, each with its own energy code and permit rule:
Elsewhere in Charleston County we also cover:
South Carolina sets the residential energy code statewide, so the attic figure is R-30 wherever it is published here; what changes is the permit desk, and 6 of the 7 publish a permit rule for insulation.
| City | Energy code | Attic R required | Permit to insulate | Building dept. |
|---|---|---|---|---|
| Sullivan's Island | 2009 IECC (state law) | R-30 | Yes | 843-883-5732 |
| Mount Pleasant | 2009 IECC (state law) | R-30 | Yes | 843-884-5184 |
| Isle of Palms | 2009 IECC (state law) | R-30 | Not published | 843-886-9912 |
| Adams Run | 2009 IECC (state law) | R-30 | Yes | 843-202-6930 |
| Awendaw | 2009 IECC (state law) | R-30 | Yes | 843-202-6930 |
| Charleston | 2009 IECC (state law) | R-30 | Yes | 843-577-5550 |
| Unincorporated Charleston County | 2009 IECC (state law) | R-30 | Yes | 843-202-6930 |
All 22 Charleston County jurisdictions side by side →
Sullivan's Island enforces the 2009 IECC (state law), which sets R-30 for an attic in new work. Whether it reaches a retrofit of an existing house is not published.
Yes. Sullivan's Island requires a permit for this work, and we pull it as part of the job.
If Dominion Energy South Carolina is your electric utility and the house has electric heat, Check-up Plus pays 90% of attic insulation, air sealing and duct sealing, up to $2,880, through March 31, 2027, through its own contractor. Berkeley Electric's map shows none of its service here. The federal 25C credit ended for work placed in service after December 31, 2025.
The typical home in Sullivan's Island dates to around the early-1980s; the Census Bureau's 2020-2024 median year built is 1981. Of its 1,088 homes, 27% went up before 1940 and 26% in 2000 or later. Half the homes here are older than that and half newer; yours may sit at either end.
Code and permit facts checked October 24, 2026, rebates October 24, 2026; housing: Census ACS 2020–2024. Sources: sullivansisland.sc.gov (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17) · scstatehouse.gov (2) · en.wikipedia.org (2, 3) · nationalregister.sc.gov (2, 3, 4, 5) · charlestonmag.com · scencyclopedia.org · isleofpalms.gov · dominionenergy.com · berkeleyelectric.coop · santeecooper.com · coastal.coop · energystar.gov · data.census.gov. These change; confirm with the building department at 843-883-5732 or the utility named on your electric bill first.
Free assessment, a measured R-value, and photos you keep either way.
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