Radon in Castle Pines: Test, Mitigate, Disclose

You have a lot on your plate when you buy or sell a home in Castle Pines. Radon should not be an afterthought. Colorado homes often test high for radon, and state law in sales and rentals requires specific disclosures. In this guide, you will learn how to test, when to mitigate, and what you must disclose so your transaction stays on track. Let’s dive in.

Why radon matters in Castle Pines

Radon is a colorless, odorless radioactive gas that can build up indoors and raise lung cancer risk. It is the leading cause of lung cancer in non-smokers in the United States. The U.S. EPA advises fixing a home at 4.0 pCi/L or higher and considering action between 2.0 and 4.0 pCi/L. You can review the EPA’s basics and planning map in the agency’s radon overview page for context on risk and action levels (EPA radon guidance).

Colorado has a high rate of elevated radon, and state health officials advise testing every home. Short-term and long-term testing guidance, plus cost expectations and mitigation tips, are summarized by the Colorado Department of Public Health and Environment (CDPHE radon testing). Douglas County also encourages testing and provides local resources for residents of Castle Pines (Douglas County radon resources).

Colorado rules: disclose, license, document

If you are selling a home, Colorado law requires you to provide a radon warning statement, share any known radon test results, and disclose any mitigation system or history. The required CDPHE radon brochure must be included with sales disclosures or contracts (Colorado seller disclosure statute).

If you are signing a residential lease, landlords must give prospective tenants a radon warning statement and any known test results before the lease is signed. Tenants have specific remedies if disclosures are missing or if elevated levels are not addressed as required by law (Colorado landlord-tenant radon statute).

Testing and mitigation work should be done by licensed professionals who follow recognized standards. The state refers consumers to licensed measurement and mitigation providers and enforces professional rules. You can review licensing expectations and standards through state-linked resources (Radon professional licensing overview) and the Division of Real Estate’s advisory on the latest contract language (Colorado DRE advisory).

How to test a Castle Pines home

Choose the right test

Short-term tests run for 48 to 120 hours and are commonly used during inspections. Long-term tests (91 days to 1 year) provide a better estimate of annual average exposure. For real estate, a licensed professional using a Continuous Radon Monitor is often preferred because it records hourly readings and environmental conditions, which supports reliable results (CDPHE radon testing).

Where and when to test

Test the lowest level that could reasonably be lived in, such as an unfinished basement. Follow closed-house conditions and placement rules for short-term tests. In a transaction, schedule testing early in the inspection window so you have time to respond to results. Professional testing typically runs about 100 to 300 dollars in Colorado, with many tests near 150 dollars, while DIY kits are cheaper but less ideal for negotiations (CDPHE radon testing).

Interpret results and decide next steps

If your result is 4.0 pCi/L or higher, plan to mitigate and verify results with a follow-up test. If the level is between 2.0 and 3.9 pCi/L, consider a long-term test or mitigation, depending on your risk tolerance and timing. Always retest after mitigation to confirm the system is performing as intended (EPA radon guidance).

Transaction timing you can follow

• Seller pre-listing: Order a professional test before going to market. If results are high, install mitigation and include the test reports, invoices, and post-mitigation verification in your disclosure packet.
• Buyer during inspection: Hire a licensed measurement pro to run a Continuous Radon Monitor during the inspection period. If elevated, use your contract rights to request mitigation, a credit, a price change, or a holdback until follow-up testing shows acceptable results.
• Tight closings: If time is short, agree on mitigation terms, a completion date, and how follow-up testing will be handled. A holdback can keep the closing on schedule while protecting both sides.

Mitigation: systems, costs, and proof

The most common fix for basements and slabs is sub-slab depressurization, which draws radon from beneath the foundation and vents it above the roofline. Crawlspaces often use sub-membrane depressurization. Sealing alone is not a complete solution, though it can support a system’s performance (CDPHE mitigation guidance).

Typical systems in Colorado run about 1,000 to 2,000 dollars, with complex layouts costing more. Ask for a written bid that lists the fan, piping path, penetrations, termination, and warranties. Hire a licensed mitigation contractor who follows ANSI/AARST standards and provides a post-installation test plan. You can confirm credentials and locate providers through state-referenced directories (Radon professional licensing overview, find certified pros in Colorado).

After installation, require a follow-up test to show the level is below the action threshold. Systems include a manometer or alarm to flag fan failure. Plan simple periodic checks and retest over time to confirm continued performance (CDPHE mitigation guidance).

Quick checklists you can use

Sellers

• Test pre-listing with a licensed professional and keep all reports.
• If results are high, mitigate and verify with a follow-up test.
• Disclose all known tests and system details and provide the CDPHE brochure as required (Seller disclosure law).

Buyers

• Book a licensed measurement professional early in the inspection period.
• If elevated, negotiate mitigation, a credit, or a holdback and require retesting.
• Review all seller test records and any system documentation before you waive contingencies.

Landlords and tenants

• Landlords must give a radon warning statement and disclose known results before lease signing.
• Tenants may test, and the law outlines remedies if disclosures are missing or high levels are not addressed (Landlord-tenant radon law).

Agents and forms

• Use the latest contract language and attach the CDPHE brochure.
• Keep test records with the file and coordinate licensed pros for any testing or mitigation.
• Review the state’s broker advisory for the most current guidance (Colorado DRE advisory).

Local resources for Castle Pines

• Colorado Department of Public Health and Environment: testing, kits, mitigation guidance, and the brochure required for sales disclosures (CDPHE radon testing).
• Douglas County Health Department: county radon page and local information for Castle Pines (Douglas County radon resources).
• EPA radon basics and planning tools (EPA radon guidance).
• Licensed professional info and standards (Radon professional licensing overview, find certified pros in Colorado).

If you want help coordinating timing, disclosures, and negotiations so radon does not derail your Castle Pines deal, reach out to the McBartlett Team. We will guide you on when to test, how to structure repair credits or holdbacks, and how to present documentation so your sale or purchase stays simple and strong.

FAQs

What is radon and why is it a concern in Colorado?

• Radon is a radioactive gas that can enter homes from the soil, and Colorado has a high rate of elevated indoor levels, which is why state health officials advise testing every home (EPA radon guidance, CDPHE radon testing).

What radon level requires action when buying a Castle Pines home?

• The EPA recommends mitigation at 4.0 pCi/L or higher and considering action between 2.0 and 4.0 pCi/L, with follow-up testing to confirm results (EPA radon guidance).

Are sellers in Colorado required to disclose radon information?

• Yes, sellers must provide a radon warning statement, share known test results and mitigation details, and include the CDPHE radon brochure with the sales contract or disclosures (Seller disclosure law).

Do landlords in Castle Pines have radon disclosure duties?

• Yes, landlords must disclose known radon test results and provide a radon warning statement before a lease is signed, and tenants have specified remedies if requirements are not met (Landlord-tenant radon law).

Who should perform radon testing during a real estate transaction?

• Hire a licensed radon measurement professional, ideally using a Continuous Radon Monitor, for reliable results and documentation recognized in negotiations (CDPHE radon testing, Radon professional licensing overview).

How much does mitigation typically cost in Colorado homes?

• Many systems cost about 1,000 to 2,000 dollars, with higher prices for complex installs, and a follow-up test should confirm the fix after installation (CDPHE mitigation guidance).