Radon Disclosure Requirements When Selling a Home in Lakewood, CO
If you're getting ready to list your house, radon disclosure is one of the newer pieces of paperwork you'll run into. Colorado law now requires sellers to state whether their home has been tested for radon and to hand over the results if it has. In Lakewood, where radon levels run higher than in most parts of the country, this isn't a box to check quickly and move past. It's worth understanding before your home hits the market, not after a buyer's inspector flags it.
This guide walks through what the law actually requires, why it matters more here than in a lot of other cities, and how to handle it so it doesn't slow down your closing.
What Colorado Law Requires Sellers to Disclose
Colorado's radon disclosure law, Senate Bill 23-206, took effect on August 7, 2023, and it changed both the standard Seller's Property Disclosure form and the Contract to Buy and Sell used across the state.
Under the law, sellers must state whether a radon test has ever been conducted on the property. If testing has happened, you're required to turn over the most recent test results and describe any mitigation work that was done in response. If no test has ever been performed, you simply disclose that fact — there's no requirement to test before you sell.
The contract also carries a bolded warning statement recommending that buyers have their own radon test performed before closing. And sellers are required to give buyers a copy of the radon information brochure published by the Colorado Department of Public Health and Environment. None of this is optional paperwork you can skip; it's built into the standard forms your agent will use.
The law doesn't force you to test your home or fix a radon problem before selling. It forces you to be honest about what you know. That distinction matters, because plenty of sellers assume disclosure means testing is mandatory, and it isn't.
Why Radon Matters More in Lakewood and Jefferson County
The EPA classifies all of Colorado as a Zone 1 radon area, meaning the average home here is expected to exceed the agency's action level of 4.0 picocuries per liter. Jefferson County's own numbers back that up: roughly half of the homes tested in the county come back above that threshold in a given year.
That's not a scare statistic meant to worry you — it's context for why the disclosure form exists in the first place. Radon comes from uranium breaking down in the soil and rock underneath a house, and the geology across the Front Range happens to produce more of it than most regions. A well-built, well-maintained home in Lakewood can still test high. It has nothing to do with how clean or updated the property is.
Because the issue is so common locally, buyers and their agents in this market are used to seeing the disclosure and often expect a conversation about it. Being prepared with a clear answer, whether that's test results in hand or an honest 'we've never tested,' puts you in a stronger position than looking caught off guard.
Should You Test Before Listing?
Testing isn't required, but a lot of sellers choose to do it anyway, and there's a reasonable case for it.
A short-term radon test takes three to seven days and typically costs somewhere in the range of $150 to $250 if you hire a certified tester, or considerably less if you use a DIY kit — Jefferson County Public Health sells basic test kits for $10, and free kits are sometimes available through the state's program.
Testing before you list gives you information on your own timeline instead of the buyer's. If the result comes back low, you have documentation ready to hand over, which can shortcut questions later. If it comes back high, you have time to research mitigation options and decide whether to address it before you go under contract, rather than scrambling during a tight inspection period.
The tradeoff is that a documented high reading becomes part of your disclosure whether you act on it or not. Some sellers prefer not to test precisely because they'd rather let the buyer's own inspection process surface the issue and negotiate from there. Both approaches are legal. The right call depends on how much certainty you want going into negotiations versus how much you'd rather keep your options open.
What to Do If Your Home Tests High
A reading above 4.0 pCi/L is common enough in this area that it rarely derails a sale by itself. What it does is open a conversation about mitigation.
A standard sub-slab depressurization system, the most common fix for radon in homes with a basement or slab foundation, runs an average cost in the range of $800 to $1,500 installed, depending on your home's layout and foundation type. Mitigation contractors in the Denver metro area are used to this work and can typically install a system within a week or two.
You have a few paths once you know your number. You can fix it before listing, so the property goes to market with a documented low reading. You can disclose the result and let the buyer decide whether to request mitigation as part of negotiations. Or you can offer a credit at closing so the buyer can handle mitigation on their own schedule after they take ownership.
None of these is automatically the right answer. A lot of it comes down to your timeline and how competitive your particular price point and neighborhood are running at the moment you list.
How Radon Disclosure Affects Negotiations and Closing
Radon comes up most often during the buyer's inspection period, even when a seller hasn't tested beforehand. Colorado's standard contract encourages buyers to test, and many do, especially with a basement or a finished lower level in the house.
If a buyer's test comes back high after you're under contract, expect one of two requests: a price adjustment to cover mitigation, or a direct request that you install a system before closing. This is a normal, common negotiation in this market, not a sign the deal is in trouble. Buyers here generally understand that a high reading is about geology, not a defect in the house.
Where sellers run into friction is when a prior test exists and wasn't disclosed, or when mitigation work was done without documentation to back it up. Keep any test reports, mitigation invoices, and system warranties in one folder from the start. Handing over a complete paper trail when it's asked for keeps things moving instead of stalling the timeline.
Working Radon Into Your Listing Timeline
If you're planning to test, build the three-to-seven-day window into your prep schedule alongside other pre-listing tasks like repairs, cleaning, and photography. There's no reason to let it hold up your listing date if you start early.
If you decide not to test upfront, at minimum have the Seller's Property Disclosure and the CDPHE brochure ready to go with your listing packet so there's no scramble when a buyer's offer comes in. Your agent should already have current versions of both.
Either way, the goal is the same: know what you're required to say, say it accurately, and have your documentation organized before a buyer's question puts you on the clock.
Frequently Asked Questions
Do I have to test my home for radon before selling in Colorado?
No. Colorado law requires you to disclose whether testing has occurred and to share results if it has, but it does not require you to test before you sell. Testing is a choice, not a legal obligation.
What if I've never tested my home and a buyer asks?
You disclose that no test has been performed — that's a fully compliant answer under the law. Many buyers will then request their own test during the inspection period, which is normal and expected in this market.
How much does radon mitigation typically cost?
A standard mitigation system for a home with a basement or slab foundation runs an average of $800 to $1,500 installed. Costs can run higher for larger homes or more complex foundation layouts.
Can a high radon reading stop my home from selling?
Rarely. A high reading is common across Lakewood and the rest of Jefferson County, and most buyers and agents treat it as a routine negotiation point rather than a reason to walk away. It typically leads to a price credit or a request for mitigation, not a canceled contract.
Is radon disclosure a Jefferson County requirement or a statewide one?
It's statewide. Senate Bill 23-206 applies to every residential sale in Colorado. Jefferson County's high local testing rate is simply one of the reasons the topic comes up more often here than in some other parts of the state.
How long does a radon test take?
A standard short-term test runs three to seven days, with results typically available within about eight days of placing the device. That's a manageable window to build into your pre-listing schedule.
If you're thinking about selling in Lakewood, call or text me at 720-625-0224 and we'll map your timing. Justin Buller | Realtor, Real Broker | 720-625-0224
