Insulation and air sealing for Rockville 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 mid-1970s, and 7% of its 71 homes went up before 1940.
Rockville runs to about 0.4 square miles and roughly 121 people. It sits about 19 miles southwest of downtown Charleston. There are around 71 housing units here. The community dates back to 1996. We cover ZIP code 29487.
We have not logged a completed job in Rockville yet. We would rather say so than put a number on this page that is not real.
The typical home in Rockville dates to around the mid-1970s. Postwar building here often meant three or four inches of fiberglass and no attempt at air sealing. If nobody has touched it since, that is what is still up there.
Many antebellum summer houses built by planters, nearly all with spacious porches, raised foundations and central halls.
Rockville is a tiny town at the south end of Wadmalaw Island on Bohicket Creek, founded as a planters' summer retreat and one of Charleston County's oldest surviving summer resorts (about 1824). Nearly all of its historic houses have spacious porches, raised foundations and central halls built to catch sea breezes, under live oaks hung with Spanish moss. The town hosts the Rockville Regatta, held since 1890.
The Census Bureau estimates 71 homes in Rockville. 5 of them (7%) went up before 1940 — 8th of 28 places on this site for pre-1940 housing. The 1970s were the busiest decade, adding 12 of today's homes (17%); 59% predate 1980 and 23% were built in 2000 or later. For Charleston County as a whole the pre-1940 share is 5%, so Rockville sits above it.
Of 58 occupied homes, 0% heat with utility gas and 93% with electricity; another 5% burn propane or other tank gas. Electric heat here is more common than across the county (76%), and ranks 5th 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.
91% of occupied homes are owner-occupied and 93% of all homes are single-family detached houses. With houses like these, the conversations we expect most are about an attic top-up over postwar fiberglass and an energy assessment before deciding what to fix first.
| Built | Homes | Share | |
|---|---|---|---|
| Before 1940 | 5 | 7% | |
| 1940s | 11 | 15% | |
| 1950s | 10 | 14% | |
| 1960s | 4 | 6% | |
| 1970s | 12 | 17% | |
| 1980s | 5 | 7% | |
| 1990s | 8 | 11% | |
| 2000s | 11 | 15% | |
| 2010s | 0 | 0% | |
| 2020 or later | 5 | 7% |
71 homes, Census ACS 2020–2024 (B25034, B25040, B25003); 58 occupied.
26 of Rockville's 71 homes (37%) date from 1950 through 1979. The leaks in houses of that era repeat: nothing over the top plates, wire and pipe holes left open, an unsealed hatch, a bath fan venting into the attic, and in ranches and split-levels, heat lost at the garage ceiling and over cantilevered floors. Sealing the plates, holes and fans comes before any more fiber, and it is usually a day's work, not a renovation.
Rockville enforces the South Carolina Energy Standard (the 2009 IECC), by state law. Rockville's town code hands building code enforcement to Charleston County, whose code list includes the 2009 International Energy Conservation Code.
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).
Rockville requires a permit for this work. Rockville's town code places building code enforcement with Charleston County, and the county's code lists insulation as work that needs a permit; the county excuses only no-inspection jobs under $1,000. The town code itself allows ordinary minor repairs and general maintenance, giving painting and minor carpentry as examples. We pull it as part of the job.
The published number is 843-202-6930. The department page is here.
Permitting is on us, not on you.
Part of Rockville sits inside Berkeley Electric Cooperative's territory, by the cooperative's own map, and Dominion Energy South Carolina is also on record in Charleston County: check whose name is on the electric bill first. If Dominion Energy South Carolina sends the bill and the house heats with electricity, Check-up Plus covers 90% of an attic, air sealing and duct sealing job, to $2,880, through March 31, 2027; it starts with Dominion's free check-up and uses the program's own contractor.
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 on the Charleston County page and in the rebate guide.
Every layer of an insulated attic, explained
Rockville borders Wadmalaw Island, Seabrook Island and Bohicket Creek. 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 7 of the 7 publish a permit rule for insulation.
| City | Energy code | Attic R required | Permit to insulate | Building dept. |
|---|---|---|---|---|
| Rockville | 2009 IECC (state law) | R-30 | Yes | 843-202-6930 |
| Wadmalaw Island | 2009 IECC (state law) | R-30 | Yes | 843-202-6930 |
| Seabrook Island | 2009 IECC (state law) | R-30 | Yes | 843-202-6930 |
| 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 →
Rockville 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. Rockville requires a permit for this work, and we pull it as part of the job.
Dominion Energy South Carolina's Check-up Plus pays 90% of attic insulation, air sealing and duct sealing, up to $2,880, until March 31, 2027, for electrically heated homes; the program's contractor does the work. Berkeley Electric members get a 5% on-bill loan instead of a rebate. The federal 25C credit ended for work placed in service after December 31, 2025.
The typical home in Rockville dates to around the mid-1970s; the Census Bureau's 2020-2024 median year built is 1975. Of its 71 homes, 7% went up before 1940 and 23% in 2000 or later. It is a median for the place, not a survey of individual houses.
Code and permit facts checked October 24, 2026, rebates October 24, 2026; housing: Census ACS 2020–2024. Sources: townofrockville.com (2, 3, 4, 5, 6, 7, 8) · charlestoncounty.gov (2, 3, 4, 5, 6, 7) · scstatehouse.gov (2) · llr.sc.gov · en.wikipedia.org (2) · nationalregister.sc.gov · www2.census.gov · dominionenergy.com · berkeleyelectric.coop · santeecooper.com · coastal.coop · energystar.gov · data.census.gov. These change; confirm with the building department at 843-202-6930 or the utility named on your electric bill first.
Free assessment, measured at the hatch, with the photographs and the number in writing.
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