Build a radon testing timeline
The most common radon failure in a transaction is not losing an argument — it is running out of days. A short-term test needs closed-building conditions established twelve hours beforehand, then the measurement period, then reporting, and then time to obtain a written quote if the result is elevated.
This works backwards from your deadline so you can see whether the sequence fits before you commit to it.
Work it through
Everything below runs in your browser. Nothing you enter is sent to us or to anyone else — this page has no server to send it to.
Contingency expiry, listing date, or closing.
Short-term fits a contract window; long-term does not.
Allow time for a site visit and a written scope.
Everyone with access must know the conditions.
What this indicates
Reading your inputs…
Why this says what it says
The full working, shown rather than summarised. Nothing below is hidden behind a toggle, because reasoning that takes a click to reach has not really been shown.
What you told us, and what each answer did
| Your answer | Value | What it influences |
|---|---|---|
| Days until your deadline | 10 days | Contingency expiry, listing date, or closing. |
| Test type | Professional continuous monitor (48 hours) | Short-term fits a contract window; long-term does not. |
| A mitigation quote may be needed | Yes | Allow time for a site visit and a written scope. |
| House is occupied or being shown | Yes | Everyone with access must know the conditions. |
What we took on trust
- The figures you enter (days until your deadline) are taken exactly as typed. We have no way to check them against a device or a laboratory record.
- Your answers about test type are taken as described. Where a description is approximate the output is approximate in the same way.
- The yes/no conditions (a mitigation quote may be needed, house is occupied or being shown) are accepted exactly as you set them. Nobody has confirmed any of them, and the output assumes each is as stated.
What is still unknown
- Actual laboratory turnaround and contractor availability in your area this week. The tool uses typical planning ranges, not commitments.
- Whether your contract permits an extension and how one is requested.
Why this stops short of a decision
This runs entirely on what you typed. Nobody has been to your house, nobody has seen the device or the laboratory record, and the choice between courses of action follows from diagnostics performed on the building. What you have here is a reading of what you reported, which is a different thing from a decision and a good basis for making one.
What would change this
- Measured laboratory turnaround times by region and season would replace the planning ranges in this tool with real distributions. We have not found published data at that resolution.
- Our contractor response time instrument would establish the quote-turnaround half of this timeline. It holds zero observations today.
- Correcting any answer above. Change an input and the output changes, which is the honest behaviour of something working from a description.
The procedure, in order
- Fix the deadline
Contingency expiry, listing date, or closing. Everything works backwards from here.
- Choose the test type
A professionally deployed continuous monitor is the fastest defensible option in a transaction; a lab kit adds transit time.
- Establish closed-building conditions
Twelve hours before the device starts: windows and exterior doors closed except normal entry, whole-house fans and window units off, permanent HVAC running normally.
- Run the measurement
For the full stated duration, with conditions maintained and everyone with access informed.
- Receive and read the result
Read the average against the action level, and read the conditions alongside it.
- Obtain a written quote if indicated
From a credentialed contractor who has seen the house. Allow three to seven days.
- Negotiate or act with time in hand
Arrive at the deadline with a result and a number rather than a request and an estimate.
The logic, in full
These are the rules the tool applies — not a summary of them. The interactive panel above evaluates exactly this list, and a build check fails if the two ever diverge. A decision tool whose reasoning you cannot inspect is a black box, and a black box is not authority.
| When | Then |
|---|---|
| Long-term test with a deadline under 90 days | A long-term detector cannot meet this deadline. Use a short-term test for the decision and place a long-term detector afterwards for the annual picture. |
| Professional continuous monitor selected | Allow one day for scheduling, half a day for conditions, two days of measurement, and same-day reporting. This is the fastest defensible path and the one a transaction usually wants. |
| Short-term kit selected | Allow half a day for conditions, the exposure period, and several days for postal transit and laboratory analysis. Transit is the part people forget. |
| A quote may be needed | Add three to seven days for a site visit and a written scope. On anything other than a simple poured basement, a contractor who quotes without visiting is guessing. |
| Fewer days remaining than the sequence requires | The test does not fit. Request an extension now rather than at the deadline, and order the fastest defensible measurement in parallel. |
| House is occupied or being shown | Tell the seller, the listing agent, and anyone showing the property in writing what closed-building conditions require. An open window during a showing is the most common way a transaction test gets invalidated. |
| The sequence fits with slack | Order it at the start of the window anyway. Slack absorbs an invalidated test; a late start does not. |
What this tool cannot do
- Timings are typical ranges for planning, not commitments. Laboratory turnaround, contractor availability, and scheduling vary.
- This tool does not know your contract. Whether an extension is available and how it is requested are questions for your agent.
- It cannot make a long-term test faster. Where an annual-scale average is what you need, the deadline and the measurement are simply answering different questions.
Related
- Selling or buying? — Your side, your timeline, your result — and what should be in the amendment.
- What does my result mean? — Your number, read against guidance and against the conditions it was measured in.
- Failed test during inspection — The inspection-window playbook, in the order the clock demands.
- How testing works — Devices, placement, closed-building conditions, and what invalidates a result.
- Monitors vs short-term tests — Which instrument to use, and why transactions favour monitors.
- Who pays — It is negotiated, not mandated. Contract language, local practice, and leverage decide it — and preparation changes the outcome more than argument does.
- Radon Testing Method Comparison Dataset — Which method answers which question — and which decisions each one cannot carry.
- Home-Sale Radon Negotiation Outcome Taxonomy — Four outcomes, what drives each, and who carries the risk afterward.
- All tools — every calculator and decision tool.
Confidence and limits of this page
Every decision resource on this platform states its own boundaries. This is not a disclaimer — it is the part of this tool you should read before relying on it.
- What we knowClaims on this page we stand behind, each traceable to an approved source or to observable structure.
- Closed-building conditions must be established twelve hours before a short-term test begins and maintained throughout it. That is protocol, not preference.
- A long-term detector requires ninety days or more and therefore cannot serve a contract deadline shorter than that.
- In an occupied home being actively marketed, several people can invalidate a test without realising it, which is why the tool tells you to notify everyone with access in writing.
- What we do not knowQuestions you may reasonably have that this page does not answer.
- Actual laboratory turnaround and contractor availability in your area this week. The tool uses typical planning ranges, not commitments.
- Whether your contract permits an extension and how one is requested.
- What research would settle itWhat it would actually take to answer the above — naming it is the difference between honesty and hedging.
- Measured laboratory turnaround times by region and season would replace the planning ranges in this tool with real distributions. We have not found published data at that resolution.
- Our contractor response time instrument would establish the quote-turnaround half of this timeline. It holds zero observations today.
- What we do not claimClaims you might expect to find here and will not, with the reason.
- We do not promise a response time or contractor availability. This platform refuses response-time claims site-wide and its build fails on any page that makes one.
- We do not claim these durations are guaranteed. They are for planning, and a test that gets invalidated resets the clock.
- What we cannot independently verifyFacts this page relies on that we could not confirm ourselves.
- Whether the parties with access to the property will actually maintain closed-building conditions, which is the most common cause of a lost window.
Radon sequence in a transaction
What it shows. Why radon runs out of days in a contract window, and which stages are fixed rather than negotiable.
Authored as SVG in this repository, with real text nodes and a long description for screen readers. Reusable under CC BY 4.0 — see the diagram library.
Sources
- U.S. EPA — Radon
- U.S. EPA — Home Buyer’s and Seller’s Guide to Radon
- U.S. EPA — A Citizen’s Guide to Radon
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