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Apex, NC
5 miles northwest
Median home built 2008, as in Holly Springs; Power from its own town system (Holly Springs: Duke Energy)
Attic insulation in ApexAttic Insulation in Holly Springs, NC
Blown-in attic insulation for Holly Springs, NC, 5 miles from Apex, plus removal and air sealing.
About Holly Springs and Its Homes
Holly Springs stayed a one-square-mile village around a Greek Revival house of about 1840 until 1987. Then came a growth spurt in the 1990s, and most homes in town date from that boom or later.
Holly Springs, in Wake County, grew from 41,570 people in 2020 to 50,288 in 2025 (Census Bureau estimates), on 18.9 square miles. That makes Holly Springs the fifth-largest town in Wake County.
Holly Springs has about 15,600 housing units, 3 percent of Wake County's; 81 percent of the town's households own their home.
Holly Springs at a Glance
- County: Wake County
- Population: 50,288 (2025), 41,570 (2020), up 21.0%
- Land area: 18.9 square miles (2,654 people each)
- Housing units: about 15,600 (±570)
- Median year built: 2008 (±1); Wake County: 2000
- Owner-occupied: 81% (±4); Wake County: 64%
- Detached houses: 79% (±4); Wake County: 58%
- Attached houses: 10% (±3)
- Apartments: 10% (±2)
- Climate zone: 4 (state code), 3 (2021 map)
- ENERGY STAR target for Holly Springs attics: R-49 from bare, R-38 over 3 to 4 inches (R-value guide)
Census Bureau estimates for Holly Springs, 2020 to 2024 (± margin of error).
Holly Springs Homes and Their Attics
Town Wells, Then Water and Sewer
For most of its history Holly Springs ran on wells. The town's own history dates its first true water system to 1968 and its wastewater system to the late 1990s. A Wake County survey found the town grew about tenfold during the 1990s alone. Outside the old village center, the land has since filled with suburban subdivisions. If your top-floor ceilings have recessed lights, their housings sit up in the attic. ENERGY STAR wants three inches of open space kept around any can light without an insulation-contact rating. A housing stamped IC may be covered. We check the label on each one before any fill goes near it.
Ranch Houses From the Quiet Decades
Before the boom, the town grew slowly. A 2014 and 2015 architectural survey of Apex, Fuquay-Varina and Holly Springs describes a village center around the 1840s landmark house, a few twentieth-century stores and institutions, and homes mixed among them. Its new entries for the town include several brick Ranch houses and one on Raleigh Street dated about 1950. An attic over a house that age may hold old insulation streaked dark gray or black. ENERGY STAR reads those streaks as dust filtered out of house air as it leaks upward through gaps in the ceiling. The leak is what needs fixing: we seal it, and the old insulation can usually stay in place under the new layer.
Attic Insulation in Holly Springs
If the joists show above the insulation in a Holly Springs attic, ENERGY STAR says to add more insulation.
From 1990 to 2009, 51 percent of Holly Springs homes were built to codes below ENERGY STAR's target; check their eaves, where ENERGY STAR says insulation is often thinnest.
The Local Climate
Holly Springs' center sits about 440 feet above sea level, 6 miles from NOAA's Apex station, the best match for Holly Springs. The station's 1991 to 2020 normals average about 3,350 heating and 1,610 cooling degree days a year, so at Holly Springs' station, heating needs outweigh cooling.
Homes by Age: What It Means for the Attic
Some 79 percent of Holly Springs housing units are detached single-family houses.
In 2010 or later, 44 percent of Holly Springs homes went up; check their air sealing as well as the depth.
Homes by Year Built
- Before 1940: under 2%, about 100 units
- 1940s: under 1%, about 40 units
- 1950s: under 1%, about 60 units
- 1960s: 0% (±1), about 70 units
- 1970s: 2% (±1), about 245 units
- 1980s: 2% (±1), about 265 units
- 1990s: 18% (±2), about 2,800 units
- 2000s: 33% (±3), about 5,200 units
- 2010s: 34% (±3), about 5,300 units
- 2020 or later: 10% (±2), about 1,570 units
Air Sealing and Duct Sealing in Holly Springs
In Holly Springs, 37 percent of homes heat with electricity and 62 percent with piped gas; forced air from either moves through ducts.
Air sealing comes first, as the EPA advises: wire and pipe holes, wall tops and soffits.
How Homes Here Are Heated
- Electricity: 37% (±3), about 5,500 households; Wake County: 55%
- Piped gas: 62% (±3), about 9,200 households
Power, Gas and Rebates
Duke Energy supplies Holly Springs' electricity. For gas, Holly Springs is in the Wake County franchise of Enbridge Gas North Carolina, and 62 percent of the town's homes heat with piped gas. Duke's free House Call fits many Holly Springs homes: 37 percent heat with electricity.
Rebate to check in Holly Springs: Smart $aver Insulate and Seal (Duke Energy; Insulation Pros is an approved trade ally). Before a job in Holly Springs, check its current terms; the Wake County page lists every program.
Attic Insulation Removal in Holly Springs
In a Holly Springs attic, only wet, moldy or animal-soiled insulation is vacuumed out (ENERGY STAR's test), once the cause is fixed, and after mice that Holly Springs attic is sanitized and deodorized; dry, clean insulation stays.
Also Serving Near Holly Springs
Nearest to Holly Springs first.
Fuquay-Varina, NC
5 miles southeast
Median home built 2011 (Holly Springs: 2008)
Attic insulation in Fuquay-VarinaCary, NC
9 miles north
Median home built 1999 (Holly Springs: 2008); 183,582 people, about 4 times Holly Springs' population
Attic insulation in CaryAngier, NC
11 miles southeast
Median home built 1998 (Holly Springs: 2008); Power from Duke Energy Progress (Holly Springs: Duke Energy)
Attic insulation in AngierMorrisville, NC
13 miles north
Median home built 2007 (Holly Springs: 2008)
Attic insulation in Morrisville
Holly Springs Insulation FAQs
Is my house in Holly Springs on a historic register?
Very likely not. Only two places in town are listed on the National Register of Historic Places: the Leslie-Alford-Mims House and the Holly Springs Masonic Lodge. There is no listed district, though the 2015 survey report recommended the Grigsby and Main Street area, tied to the town's African American community, as eligible. The Leslie-Alford-Mims House is also a local historic landmark. The town joined the Wake County historic preservation program in 1992. Unless your house is a designated landmark, attic work needs no historic review.
Why is the upstairs of our Holly Springs house so hot in July?
Start with the attic over it, which soaks up summer heat and can pass it down. ENERGY STAR explains that air moving in at the soffits and out at the ridge carries that heat away, which only works if insulation never covers the soffit vents. A radiant barrier can help too, mostly where the attic has little insulation or the ductwork runs through it. Building America research finds the gain is small once an attic already carries a full blanket of insulation. Sealing the ceiling and bringing the insulation up to depth come first, and that is our work.
Our subdivision house is only about twenty years old. Can its attic still leak air?
Yes, and it is worth a look. The ENERGY STAR checklist of attic leaks includes the holes drilled for wiring and plumbing. It goes on to the chases that carry ducts and furnace flues up from below. We find those openings from the attic side, close each with a material suited to it, and only then add insulation.
Does attic insulation in Holly Springs need a permit?
Holly Springs Town Hall can say whether Wake County Permits and Inspections, the town itself or another office handles permits in Holly Springs; ask before work starts.
Helpful Guides
- Median home built 2008: a hot upstairs and bonus rooms over garages
- Power from Duke Energy: high summer electric bills and home energy audits
Sources
Census Bureau figures for Holly Springs, NOAA normals for the Apex station, Duke Energy (October 2026). Compiled by Insulation Pros. How the town pages are made.
Sources for the Holly Springs notes and questions (read October 20, 2026):
- Wake County Survey Update, Phases I and II, 2007 (Wake County Reconnaissance Survey Update 2005-2006, Edwards-Pitman Environmental, for the NC HPO)
- Historic Architecture Survey Update of Apex, Fuquay-Varina, and Holly Springs, 2015 (New South Associates, for the NC HPO)
- Great Depression to Early 1970s: Holly Springs Rebounds, Town of Holly Springs history
- Year Structure Built (table B25034), Holly Springs town, American Community Survey 2020-2024 5-year estimates, U.S. Census Bureau via Census Reporter
- Attic Insulation Project, ENERGY STAR
- Attic Air Sealing Project, ENERGY STAR
- NC Listings in the National Register of Historic Places, NC State Historic Preservation Office
- Historic Preservation in Holly Springs, Town of Holly Springs
- About Attic Ventilation, ENERGY STAR do-it-yourself guide
- Attic Radiant Barriers, Building America Solution Center (Pacific Northwest National Laboratory, U.S. DOE)
Holly Springs, NC
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Insulation Pros is an insulation contractor serving North Carolina, Holly Springs and the rest of Wake County included.
Reach us
Send the square footage of your Holly Springs attic, or call (336) 870-3893.