2026-02-09 · 4 min read
Radon Mitigation Cost in Delaware (2026)
Northern Delaware sits in EPA Zone 1 — the Piedmont geology pushes readings high in New Castle County. Mitigation costs $1,100–$2,400 for most homes.
Radon in Delaware
Delaware is a small state with a distinct north-south radon divide. New Castle County — Wilmington and surrounding suburbs — sits on the Piedmont and is EPA Zone 1. This is the same geological zone as southeastern Pennsylvania and northern Maryland, all of which have elevated radon.
Kent County (Dover area) is Zone 2. Sussex County (beach communities, Rehoboth, Lewes) is Zone 3.
If you're in New Castle County and haven't tested, testing is strongly recommended.
Cost by Foundation Type
Finished Basement: $1,100–$2,300
Northern Delaware's older housing stock — particularly in Wilmington, Newark, and suburban New Castle County — typically has full basements. Pricing aligns with the mid-Atlantic region.
- Unfinished basement: $1,100–$1,600
- Finished basement: $1,500–$2,300
Slab-on-Grade: $1,000–$1,900
More common in newer construction and southern Delaware. Standard installation pricing.
Crawl Space: $2,500–$5,000
Found in some older Delaware homes, particularly in Kent and Sussex counties. Pricing follows regional norms.
Delaware-Specific Factors
Philadelphia labor market: Delaware contractors compete in the same labor market as southeastern Pennsylvania. Rates are above national averages but below New York or Boston.
Real estate: Delaware's active real estate market — particularly in the Wilmington suburbs — makes radon testing common in transactions. Having a current test and a working system improves disclosure.
Contractor availability: The Wilmington metro has good contractor availability. Southern Delaware has fewer options.
Delaware Resources
- DE Division of Public Health: dhss.delaware.gov (search "radon")
- Verify NRPP: radonproficiency.org
- Verify NRSB: nrsb.org
Frequently Asked Questions
Is radon a problem in Delaware?
Yes, particularly in northern Delaware. New Castle County sits on the Piedmont with crystalline rock and schist geology — EPA Zone 1. Kent and Sussex counties in the southern Coastal Plain are Zone 2–3 and generally lower risk.
How much does radon mitigation cost in Delaware?
Expect $1,100–$2,200 for most Wilmington-area homes. Delaware shares labor markets with Philadelphia and the Baltimore-DC corridor, keeping rates at mid-Atlantic levels.
Does Delaware require radon contractor licensing?
Delaware does not have a mandatory state radon contractor licensing program. Verify NRPP or NRSB certification.
Find a Certified Mitigator Near You
Every contractor on RadonBase is NRPP or NRSB certified — mitigators only, no testers.
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