Insulation and air sealing for Summerville 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 3% of its 22,776 homes went up before 1940.
Summerville runs to about 23 square miles and roughly 51,654 people. It sits about 21 miles northwest of downtown Charleston. There are around 22,776 housing units here. The community dates back to 1847. We cover ZIP codes 29483, 29484, 29485 and 29486.
We have not logged a completed job in Summerville yet. We would rather say so than put a number on this page that is not real.
The typical home in Summerville 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.
Largely single-family homes of many ages: the historic district holds about 700 buildings, most from before World War I, including bungalows, raised cottages and Charleston single houses, while the newest growth is in the planned community of Nexton.
We work across Summerville rather than one corner of it — Downtown Historic District, Nexton, Oakbrook, Knightsville, Brownsville, Branch Creek and South Pointe 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.
Mostly in Dorchester County, with parts reaching into Berkeley and Charleston counties, Summerville began as a pineland summer retreat and still has on its books a tree-protection ordinance first passed in 1847. It lies in the Middleton Place-Summerville Seismic Zone, home to about 70 percent of South Carolina's earthquakes.
The Census Bureau estimates 22,776 homes in Summerville. 753 of them (3%) went up before 1940 — 14th of 28 places on this site for pre-1940 housing. The 2000s were the busiest decade, adding 7,475 of today's homes (33%); 19% predate 1980 and 52% were built in 2000 or later. For Dorchester County as a whole the pre-1940 share is 2%, so Summerville sits above it.
Of 21,228 occupied homes, 19% heat with utility gas and 79% with electricity. Electric heat here is more common than across the county (75%), and ranks 16th of 28 on this site. Which utility program can contribute depends on the heating fuel and on who sends the bill, so that is the first thing an assessment pins down.
69% of occupied homes are owner-occupied and 64% of all homes are single-family detached houses, with 1,091 mobile homes in the count. Read together, those numbers point toward air sealing on newer houses that already have depth and an energy assessment before deciding what to fix first.
| Built | Homes | Share | |
|---|---|---|---|
| Before 1940 | 753 | 3% | |
| 1940s | 63 | 0% | |
| 1950s | 471 | 2% | |
| 1960s | 982 | 4% | |
| 1970s | 2,034 | 9% | |
| 1980s | 3,373 | 15% | |
| 1990s | 3,161 | 14% | |
| 2000s | 7,475 | 33% | |
| 2010s | 3,959 | 17% | |
| 2020 or later | 505 | 2% |
22,776 homes, Census ACS 2020–2024 (B25034, B25040, B25003); 21,228 occupied.
11,939 of Summerville's 22,776 homes (52%) 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.
Summerville enforces the South Carolina Energy Standard (the 2009 IECC), by state law. The town lists the 2009 International Energy Conservation Code beside the 2021 South Carolina Residential Code, and Town Code Section 6-37 adopts new editions on the state's dates.
Under that edition the required attic value for new work here is R-30, and walls R-13. For comparison, the Department of Energy recommends R49 for an uninsulated attic in climate zone 3A, where Summerville sits, and R38 where there are already a few inches up there.
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).
Summerville publishes no answer either way. Insulation and air sealing appear on neither the permit-required list nor the exempt list. Summerville's Building Department says it requires permits and inspections for new buildings, renovations, and repairs to building structures and systems, and it names carpet installation and painting as work that does not need a building permit. Insulation is not named either way, so call the department before an insulation-only job. We confirm it with the department before we start and pull whatever is needed. We would rather write that here than guess on your behalf.
The published number is 843-851-5200. The department page is here.
Permitting is on us, not on you.
Part of Summerville sits inside Berkeley Electric Cooperative's territory, by the cooperative's own map, and Dominion Energy South Carolina, Edisto Electric Cooperative and Coastal Electric Cooperative are also on record in Dorchester 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. Coastal Electric members can borrow up to $10,000 on the bill; Edisto Electric lists no insulation program. Income-qualified households can apply to Palmetto Community Action Partnership (843-720-5336) for free weatherization instead. The Dorchester County page and the rebate guide carry the full rules.
Every layer of an insulated attic, explained
Summerville borders North Charleston, Lincolnville, Ladson, Sangaree and Ashley River. These are the ones we also cover, each with its own energy code and permit rule:
Elsewhere in Dorchester 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 none of the 7 publishes a permit rule for insulation.
| City | Energy code | Attic R required | Permit to insulate | Building dept. |
|---|---|---|---|---|
| Summerville | 2009 IECC (state law) | R-30 | Not published | 843-851-5200 |
| North Charleston | 2009 IECC (state law) | R-30 | Not published | 843-740-2562 |
| Lincolnville | 2009 IECC (state law) | R-30 | Not published | 843-873-3261 ext. 3 |
| Ladson | 2009 IECC (state law) | R-30 | Not published | 843-719-4292 |
| Sangaree | 2009 IECC (state law) | R-30 | Not published | 843-719-4292 |
| Unincorporated Dorchester County | 2009 IECC (state law) | R-30 | Not published | 843-832-0011 |
| Ridgeville | 2009 IECC (state law) | R-30 | Not published | 843-832-0011 |
All 4 Dorchester County jurisdictions side by side →
Summerville 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.
Summerville publishes no rule either way, so we ask its building department at 843-851-5200 before the job is scheduled.
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. Coastal Electric lends up to $10,000. The federal 25C credit ended for work placed in service after December 31, 2025.
The typical home in Summerville dates to around the early-2000s; the Census Bureau's 2020-2024 median year built is 2001. Of its 22,776 homes, 3% went up before 1940 and 52% 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: summervillesc.gov (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19) · scstatehouse.gov · library.municode.com · en.wikipedia.org (2) · scencyclopedia.org · schpr.sc.gov · scemd.org · www2.census.gov · tigerweb.geo.census.gov · dominionenergy.com · berkeleyelectric.coop · santeecooper.com · coastal.coop · energystar.gov · data.census.gov. These change; confirm with the building department at 843-851-5200 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.
Book my free assessment →