Spray foam insulation in Williamsburg, VA: get up to 3 quotes from vetted local installers
Request free quotes from up to three vetted spray foam installers serving Williamsburg and nearby Williamsburg city. Below: what your climate zone means for open vs closed cell, how much insulation to ask for, Virginia's energy code, and the rebates we could verify.
- Climate zone: 4A (2021 IECC)
- Attic target: R-60 (ENERGY STAR, uninsulated attic)
- State code: 2021 IECC with Virginia amendments (Virginia Construction Code)
- Utility rebates we verified: Dominion Energy Virginia Home Energy Evaluation
- Federal 25C credit: ended for 2026 installs
Facts last checked October 16, 2026. Sources are linked in each section.
Where we match quotes from this page
Requests from Williamsburg and ZIP codes whose center is within about 20 miles of it go to our Williamsburg, VA partner installers (30 ZIP codes): 23011, 23030, 23056, 23061, 23062, 23072, 23081, 23089, 23128, 23147, 23156, 23168, 23185, 23188, 23430, 23602, 23603, 23604, 23606, 23608, 23690, 23691, 23692, 23693, 23696, 23839, 23846, 23881, 23883, 23899. Outside these? Send the form anyway and we'll tell you if we can't match you.
Climate zone 4A: what it means for spray foam
Williamsburg's central point is in Williamsburg city, which the 2021 IECC county map assigns to climate zone 4A (mixed-humid in DOE's Building America terms). Zone 4A is a moist ("A") zone, which drives the vapor and R-value rules below.
Other counties within our Williamsburg service radius: Charles City County (4A), Gloucester County (4A), Henrico County (4A), Isle of Wight County (3A), James City County (4A), King and Queen County (4A), Mathews County (4A), New Kent County (4A), Newport News city (3A), Prince George County (4A), Surry County (3A), York County (4A). Not all are the same zone, so check your own county if you live outside Williamsburg proper.
Source: PNNL-33270, Guide to Determining Climate Zone by County (IECC 2021).
Open cell vs closed cell in Williamsburg, VA
Attic roofline: both foams are used. The IRC (R806.5) does not require a vapor-retarder coating on open-cell foam under the roof deck in zone 4A (that requirement starts in zone 5), but for hybrid assemblies the foam layer at the deck must be at least R-15 to control condensation. Ask the installer how they manage winter moisture at the roof sheathing.
Closed cell is the usual choice for rim joists, basement and crawlspace walls, where its vapor resistance (about 1.5–2" makes it a Class II vapor retarder) matters most.
Metal buildings, pole barns and shops
For uninsulated metal roofs and walls, closed-cell foam sprayed directly on the panels is used both as insulation and as a vapor retarder to stop condensation from forming and dripping on the underside of the metal. When you request quotes, choose "Metal building / pole barn" and give the building's footprint and wall height; ask each installer for foam type, thickness, and whether a thermal or ignition barrier coating is required for how the building will be used. We don't have data on how common these buildings are around Williamsburg, so we won't guess.
How much insulation to ask for
| Where | ENERGY STAR recommendation for zone 4A |
|---|---|
| Attic, uninsulated | R-60 |
| Attic with 3–4" of existing insulation | add R-49 |
| Floor over unconditioned crawlspace/basement | R-19 |
| Basement or crawlspace walls | R-10 continuous or R-13 cavity |
| Exterior walls (when re-siding) | add R-5 to R-10 insulative wall sheathing beneath new siding |
To reach R-60 with foam alone you'd need roughly 16.2–17.1" of open cell (about R-3.5 to R-3.7 per inch) or 8.6–12.0" of closed cell (about R-5 to R-7 per inch). Many roofline spray foam jobs are installed thinner than that and justified through the code's performance path or the unvented-attic rules, so ask every installer to write the foam type, thickness and resulting R-value on the quote and explain how it meets your local code.
Source: ENERGY STAR, Recommended Home Insulation R-Values (based on 2021 IECC). ENERGY STAR's figures are recommendations for existing homes; your local code sets the legal minimum for new work.
Virginia energy code
2021 IECC with Virginia amendments (Virginia Construction Code), effective January 18, 2024. Virginia amendments set wood-frame walls at R-15 (or R-13+1) in all zones and raise the air-leakage limit to 5 ACH50.
Source: NAHB, "Residential Provisions of the IECC: State Adoption Status" (current as of May 2026); official state status at DOE Building Energy Codes Program.
Homes in Williamsburg, VA
Census figures for Williamsburg city (ACS 2020–2024 5-year estimates): about 5,799 housing units, a median year built of 1987, 38% built before 1980 and 17% built in 2010 or later. 42% are single-family detached homes and 0% are mobile/manufactured homes. 53% of occupied homes are owner-occupied, with a median owner-reported home value of $428,100.
- 58% of homes heat with electricity (furnaces, heat pumps or baseboard). Several utility insulation rebates are aimed at electric-heat or central-A/C customers, so check the programs below.
Rebates and incentives for Williamsburg, VA
Utility programs that may apply, depending on which utility serves your address:
Dominion Energy Virginia Home Energy Evaluation
Rebates for attic, wall, basement-wall and crawlspace insulation plus air and duct sealing after a comprehensive home energy audit by a participating contractor, who submits the rebate.
Read on the program's own page October 16, 2026. Programs change; confirm before you sign.
Virginia state Home Energy Rebates
Not yet launched Home Energy Rebate Programs
Electrification/appliance rebates (HEAR): "No. Virginia Energy's ability to launch the programs is contingent on US Department of Energy's review and approval of Virginia Energy's application documents."
Whole-home efficiency rebates (HOMES/HER): "Virginia Energy finished submitting application documents for the Commonwealth's allocation of Home Energy Rebate Programs funding in June 2025. It is now updating application documents to conform with updated program documents released by US Department of Energy on May 29, 2026."
Max rebate (per official page): High Efficiency Appliance Rebates will provide up to $14,000 per household in up-front rebates to support households in purchasing certain types of high efficiency electric appliances.
Official source: Virginia Energy. Status text compiled via referencesource.org, last checked by them August 25, 2026. Full Virginia rebate page →
What spray foam costs (national published ranges)
We don't have enough local quotes for Williamsburg, VA to publish local prices, and we won't make them up. These national ranges are a starting point; your installers' quotes are what count.
| Example job (typical thickness) | Estimated installed range |
|---|---|
| 1,000 sq ft attic roofline, open cell (6") | $3,600–$9,600 |
| 1,000 sq ft attic roofline, closed cell (3") | $3,900–$9,300 |
| 1,500 sq ft walls, open cell (3.5") | $3,150–$8,400 |
| 1,500 sq ft walls, closed cell (2") | $3,900–$9,300 |
| 200 sq ft rim joists, closed cell (2") | $520–$1,240 |
Board feet × Angi's 2026 installed price per board foot. Angi reports a national average spray foam project of $2,888 (typical $1,455–$4,337). Check a quote you already have →
Questions to ask each installer
- Foam type, brand, thickness and resulting R-value for each area, in writing.
- Which climate zone and code edition they're designing to.
- Whether removal of old insulation, air sealing, and any required ignition/thermal barrier coating are included.
- Whether they participate in Dominion Energy Virginia Home Energy Evaluation, and who files the paperwork.
- Whether they'll do (or coordinate) combustion safety testing if you have gas appliances.
FAQ
What climate zone is Williamsburg, VA in?
Williamsburg city is IECC 2021 climate zone 4A, per PNNL's county list (PNNL-33270).
Should I use open-cell or closed-cell spray foam in Williamsburg, VA?
Both work at the roofline in zone 4A; closed cell is the usual pick for rim joists and basement or crawlspace walls. In hybrid roof assemblies the foam layer must be at least R-15.
How much attic insulation do homes in Williamsburg, VA need?
ENERGY STAR recommends R-60 for an uninsulated attic in zone 4A (or adding R-49 on top of 3–4 inches of existing insulation). Virginia's code: 2021 IECC with Virginia amendments (Virginia Construction Code).
Are there spray foam or insulation rebates in Williamsburg, VA in 2026?
The federal 25C tax credit does not apply to insulation installed after December 31, 2025. Utility programs that may apply, depending on which utility serves your address: Dominion Energy Virginia Home Energy Evaluation. Virginia's state Home Energy Rebate program status: Not yet launched.
How much does spray foam cost in Williamsburg, VA?
We don't publish local prices until we have enough real local quotes. National published ranges are about $0.60–$1.60 per board foot for open cell and $1.30–$3.10 for closed cell, installed (Angi, 2026), and many companies have a $1,000–$2,000 minimum.
How does requesting quotes work?
Fill in the form once. We pass your request to up to three vetted partner installers who serve Williamsburg, VA, and they contact you to schedule an estimate. It's free and there's no obligation.
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