Find DEP-Certified Radon Professionals in Pennsylvania

How Do I Verify a Radon Contractor Is DEP-Certified?

PA DEP certification for radon mitigation is issued and renewed by the Bureau of Radiation Protection. Before any money changes hands, verify the contractor's active certification status directly through the official DEP database — not just by taking their word for it, and not based on a printed certificate they show you (certificates can lapse after printing).

What to Ask and What to Check

When contacting a radon contractor, request the following before agreeing to any work:

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  DEP Certification Number

  Ask for their PA DEP radon mitigation certification number and verify it at dep.pa.gov. Confirm the certification is active, not expired, and covers the type of work required (mitigation, not just testing).
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  Liability Insurance

  Request a certificate of insurance naming you as an additional insured for the project duration. Mitigation involves core drilling and penetrating your building envelope — liability coverage is non-optional.
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  ANSI-AARST Compliance

  Ask specifically: "Do you follow ANSI-AARST CCAH (Standard of Practice for the Installation of Radon Mitigation Systems in Detached Houses) for residential installs?" This is the industry standard that governs system design, pipe sizing, fan selection, and post-testing protocol.
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  Post-Mitigation Testing

  Confirm that post-mitigation testing is included in the quoted price. It should be. If a contractor does not include post-mitigation testing, treat that as a red flag.
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  Written Warranty

  Ask for a written warranty covering both the installed system and the fan. Reputable contractors typically offer one-year parts-and-labor warranties; some offer two-year coverage. Verbal assurances are not sufficient.

Find Contractors by Region

Use the regional directory below to find cities in your area, then visit the city page for detailed local contractor listings, radon risk data, and direct quote requests.

What to Expect from a Certified Radon Mitigation

A professional radon mitigation engagement follows a defined sequence. Understanding each phase helps you evaluate whether the contractor you're considering is following best practices — and gives you benchmarks to measure the quote against.

Initial Diagnostic Testing

Before designing a mitigation system, a DEP-certified contractor will perform a pre-mitigation radon test (if one hasn't already been done) and a sub-slab communication test. The communication test — typically performed by drilling a small test hole and using a manometer or smoke pencil — determines how well air moves through the sub-slab material. High-permeability sub-slab fill (crushed stone) communicates well and typically requires fewer suction points. Low-permeability conditions (packed clay, concrete residue) require more points or higher-static fans. This diagnostic step determines system design — skip any contractor who jumps straight to installation without it.

System Design and Installation (Typically 1–2 Days)

For a standard single-suction-point residential ASD installation, expect:

• Core drilling through the basement slab at the diagnostic-determined location
• PVC pipe routing (3" or 4") from sub-slab to above the roofline or to an exterior discharge point
• Inline fan installation (attic, crawlspace, or exterior) with weatherproof electrical connection
• Slab penetration sealing around the suction pipe with hydraulic cement and caulk
• U-tube manometer installation on the suction pipe — the homeowner-readable performance indicator
• Sealing of other potential radon entry points (sump pit lids, floor cracks, utility penetrations) as needed

Most single-point residential installations are completed in 4–8 hours. Multi-point systems or complex foundation types may require a second day. The system is operational immediately upon installation — the fan runs continuously.

Post-Mitigation Testing (24-Hour Protocol)

Post-mitigation testing should be performed a minimum of 24 hours after installation, under closed-house conditions, using a continuous radon monitor (CRM) or short-term charcoal canister placed in the lowest livable area. Results below 4.0 pCi/L confirm the system is performing to standard. Results at or above 4.0 pCi/L require system adjustment — additional suction points, fan upgrade, or improved sealing — at no additional charge under a standard warranty. Request a written copy of the post-mitigation test results; you will need them for any future real estate transaction disclosure.

Ongoing Monitoring Recommendations

After a successful mitigation, PA DEP and EPA recommend retesting every two years under normal conditions, or immediately after any renovation affecting the foundation, slab, drainage, or HVAC system. Check the U-tube manometer quarterly — a flat reading (no differential) means the fan has stopped and radon levels will rise. Consumer continuous monitors (such as the Airthings View Plus) provide ongoing visibility between formal professional tests and will alert you to any system failure or seasonal spike before your next scheduled retest.

Questions to Ask Before Hiring a Radon Contractor

These five questions, asked before agreeing to any work, separate qualified DEP-certified professionals from unqualified operators.

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