Insulation and air sealing for Mount Pleasant 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-2000s, and 1% of its 44,376 homes went up before 1940.
Mount Pleasant runs to about 50 square miles and roughly 93,993 people. It sits about 4 miles northeast of downtown Charleston. Around 44,376 housing units sit inside those boundaries. The community dates back to 1837. We cover ZIP codes 29464, 29465, 29466 and 29429.
No completed job in Mount Pleasant is logged in our records yet, and this page will say so until one is.
The typical home in Mount Pleasant dates to around the early-2000s. 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.
The Old Village has 18th-, 19th- and early 20th-century houses in vernacular Georgian, Greek Revival and Gothic Revival styles; the earliest were simple cottages, with larger houses built once planters lived in town year-round.
We work across Mount Pleasant rather than one corner of it — Old Village, I'On, Scanlonville, Hobcaw Point and Snee Farm included. Construction and vintage change between them, sometimes by thirty years and a whole different framing method, which decides whether a wall can be dense-packed at all.
Mount Pleasant sits on the east side of Charleston Harbor and the tidal Wando River; it began as a summer resort, and its oldest neighborhood, the Old Village, has houses from the 1700s through the early 1900s. The town limits have since pushed about 24 miles northeast along U.S. 17, and the population roughly doubled between 1990 and 2000 in the growth that followed Hurricane Hugo in 1989.
The Census Bureau estimates 44,376 homes in Mount Pleasant. 286 of them (1%) went up before 1940 — 18th of 28 places on this site for pre-1940 housing. The 2010s were the busiest decade, adding 11,052 of today's homes (25%); 16% predate 1980 and 51% were built in 2000 or later. For Charleston County as a whole the pre-1940 share is 5%, so Mount Pleasant sits below it.
Of 39,884 occupied homes, 18% heat with utility gas and 77% with electricity; another 3% burn propane or other tank gas. Electric heat here is more common than across the county (76%), and ranks 19th of 28 on this site. That is why the assessment asks how the house is heated: the fuel and the name on the utility bill decide which program, if any, can pay toward the work.
74% of occupied homes are owner-occupied and 64% of all homes are single-family detached houses, with 262 mobile homes in the count. On a housing mix like this, the likely starting points are air sealing on newer houses that already have depth and an energy assessment before deciding what to fix first.
| Built | Homes | Share | |
|---|---|---|---|
| Before 1940 | 286 | 1% | |
| 1940s | 319 | 1% | |
| 1950s | 1,592 | 4% | |
| 1960s | 984 | 2% | |
| 1970s | 3,926 | 9% | |
| 1980s | 6,287 | 14% | |
| 1990s | 8,457 | 19% | |
| 2000s | 9,471 | 21% | |
| 2010s | 11,052 | 25% | |
| 2020 or later | 2,002 | 5% |
44,376 homes, Census ACS 2020–2024 (B25034, B25040, B25003); 39,884 occupied.
22,525 of Mount Pleasant's 44,376 homes (51%) were built in 2000 or later. Depth is rarely what is missing in houses this new; air paths are: attached garages, bonus rooms over them, the chase around a high-efficiency flue, and the thin edge where blown fiber meets the wall plate. They usually earn their money back on sealing rather than on more fiber.
Mount Pleasant enforces the South Carolina Energy Standard (the 2009 IECC), by state law. The town's residential plan checklists cite the 2009 IECC with the 2021 IRC, and the town has said applications made after January 1, 2027 must be designed to the 2024 residential code; the energy standard stays the 2009 edition, because state law sets it.
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).
Mount Pleasant requires a permit for this work. A small job is the exception. The town says a building permit is needed by anyone who intends to alter or repair a building, but under Town Ordinance 150.002 "where valuation (material and labor) does not exceed $1,000 a permit is not necessary, unless an inspection is required." Insulation is not on the town's other no-permit list. We pull it as part of the job.
The published number is 843-884-5184. The department page is here.
Permitting is on us, not on you.
Part of Mount Pleasant 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. The Charleston County page and the rebate guide carry the full rules.
Every layer of an insulated attic, explained
Mount Pleasant borders Sullivan's Island, Charleston, Cooper River, Wando River and Charleston Harbor. 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. |
|---|---|---|---|---|
| Mount Pleasant | 2009 IECC (state law) | R-30 | Yes | 843-884-5184 |
| Sullivan's Island | 2009 IECC (state law) | R-30 | Yes | 843-883-5732 |
| Charleston | 2009 IECC (state law) | R-30 | Yes | 843-577-5550 |
| Adams Run | 2009 IECC (state law) | R-30 | Yes | 843-202-6930 |
| Awendaw | 2009 IECC (state law) | R-30 | Yes | 843-202-6930 |
| Unincorporated Charleston County | 2009 IECC (state law) | R-30 | Yes | 843-202-6930 |
| Edisto Island | 2009 IECC (state law) | R-30 | Yes | 843-202-6930 |
All 22 Charleston County jurisdictions side by side →
Mount Pleasant 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. Mount Pleasant 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 Mount Pleasant dates to around the early-2000s; the Census Bureau's 2020-2024 median year built is 2000. Of its 44,376 homes, 1% went up before 1940 and 51% 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: tompsc.com (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18) · scstatehouse.gov (2) · en.wikipedia.org (2, 3, 4) · scencyclopedia.org · nationalregister.sc.gov · codelibrary.amlegal.com · www2.census.gov · dominionenergy.com · berkeleyelectric.coop · santeecooper.com · coastal.coop · energystar.gov · data.census.gov. These change; confirm with the building department at 843-884-5184 or the utility named on your electric bill first.
Free assessment: what depth you have now, what it has settled to, and what the sealing is worth.
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