Direct answer
These are the rules every page on DuctCleaning.ws is written to. Primary sources come first, government sources outrank industry sources, every number carries a label saying how strongly it is supported, and a number we cannot trace to a source does not get published at all. We take no money from duct cleaning companies. Review dates change only when a review actually happened.
Source hierarchy
When two sources conflict, position in this list decides which one leads, unless there is a specific documented reason to depart from it, in which case we state the reason on the page.
| Tier | Examples | What we use it for |
|---|---|---|
| 1. Government and courts | U.S. Environmental Protection Agency (EPA) guidance; state attorney general complaints, rulings, and press releases; federal agency documents | Positions, regulatory facts, and documented outcomes. These are the only sources we treat as settling a question on their own. |
| 2. Standards and technical bodies | Organizations that publish documented technical positions on duct systems and materials | Technical framing and points of agreement between regulator and industry, which carry extra weight when they coincide. |
| 3. Trade associations | The National Air Duct Cleaners Association (NADCA) | Industry practice, scope norms, and consumer warnings, always attributed as industry guidance. |
| 4. Investigative journalism | Television and newspaper investigations, particularly where reporters obtained documents or interviewed named consumers | Documented individual cases and Better Business Bureau study findings. |
| 5. Commercial cost publishers | Home-services cost pages and contractor trade publications | Pricing only, only when dated and current, and only after checking whether several of them are reprinting one dataset. |
| Not a source | Duct cleaning company blogs, HVAC marketing content, content farms, and undated aggregator pages | Read to learn what claims are circulating. Never used to establish that a claim is true. |
How claims are labeled
Every figure gets a label the first time it appears on a page. The label is part of the claim, not decoration around it, and it tells you what kind of thing you are looking at before you decide what to do with it.
| Label | What it means | Example of something that earns it |
|---|---|---|
| Verified fact | A stated position, regulatory fact, or documented outcome from a tier 1 source, quoted or paraphrased accurately. | EPA does not recommend routine duct cleaning, only cleaning as needed. |
| Typical range | A price band published by multiple genuinely independent sources that agree within a reasonable spread. | $25 to $50 per supply vent, which appears in four or more separate publications. |
| Industry guidance | Guidance from a trade association about its own industry. Useful and often candid, but not neutral. | NADCA’s warning about extremely low-cost whole-house specials. |
| Single source | Exactly one published source carries this figure. We report it and mark it rather than promoting it to consensus. | The $200 minimum service fee, which appears in one publication. |
| Editorial estimate | Our own judgment, built from sourced inputs, identified as ours. Used where the market has no published figure but a planning number is genuinely useful. | Our $300 to $700 headline planning range for a single-system home. |
| Example calculation | Arithmetic shown so you can follow or reject it. Not a market observation. | Multiplying a vent count by a per-vent rate to reach a total. |
| Editorial assessment | Our interpretation of what the evidence means, as distinct from the evidence itself. | Our conclusion that the gap between two published price ranges is definitional rather than empirical. |
We do not publish a number we cannot source
This is the rule the rest of the policy exists to protect. If we cannot trace a figure to a named source with a date, it does not appear, in any form, including as an approximation, a “roughly,” or a range wide enough to be safe.
The rule has teeth, and the visible evidence is the list of things we do not publish. There is no dollar figure on this site for the price difference between flexible and rigid duct, because no source publishes one. There is no accessibility multiplier presented as market data, no contamination surcharge, and no duct-cleaning-specific mold surcharge, for the same reason. Where our calculator has to apply an adjustment in order to function, the adjustment is disclosed on the methodology page as our assumption, with the plain statement that the direction is documented and the magnitude is ours.
The temptation to fill gaps is strong, because a table with a hole in it looks unfinished. We would rather publish the hole. The list of claims we could not verify is one of the most useful pages on the site precisely because nobody else publishes theirs.
Trade-association guidance is not government guidance
NADCA produces genuinely useful material and is often blunt about problems in its own industry, including operators who take a low-priced job and leave, companies that assert mold is present without a proper inspection, and firms that use its logo without being members. We cite all of that.
But NADCA is a trade association, not a regulator. Its members sell the service it describes. So we apply three rules:
- Always attributed as industry guidance, never presented as a neutral or official position.
- Paired with a government source wherever a claim carries real consequences for a reader’s money or health.
- Never counted twice. NADCA’s cost guidance and EPA’s cost figure are the same $450 to $1,000 range. Presenting them as two sources agreeing would be a straightforward misrepresentation of the evidence, and it is one we see constantly.
We also do not state that NADCA certification is legally required, because it is a voluntary industry credential rather than a government license, and we are not certified by or affiliated with NADCA or any other body. What certification does and does not guarantee has its own page.
Independence from the industry we cover
No duct cleaning company, franchise, manufacturer, trade body, or lead-generation network has paid for, sponsored, reviewed, or influenced anything on this site. We do not accept payment for coverage, placement, directory listings, or link insertion, and we do not sell reader contact details, because we do not collect them.
The site does not currently earn revenue. If and when it carries display advertising or affiliate links, those relationships will be disclosed on the page where they appear and will have no bearing on editorial conclusions. See the funding section of the about page and the affiliate disclosure.
The practical test of independence in this category is whether a publication can tell you not to buy. Ours does, on most pages, because that is what the evidence supports.
How we handle health topics
Indoor air quality is where this category does its most aggressive selling and where a publisher can do the most damage. Our rules are absolute rather than case-by-case.
- We never state or imply that duct cleaning cures allergies, treats asthma, prevents disease, removes all mold, or guarantees healthier air.
- We report EPA’s finding that duct cleaning has never been shown to prevent health problems, and we are explicit that this applies to the entire service category. It is not a statement about disreputable operators, and it does not imply the service becomes health-protective in better hands.
- We distinguish building maintenance from medical advice, and we do not give the latter. If someone in a household is unwell, that is a question for a clinician, not for a duct cleaning site.
- Mold gets particular care. Visual inspection alone cannot confirm mold, laboratory confirmation is inexpensive, wet or moldy duct insulation cannot be effectively cleaned and should be removed and replaced, and the underlying moisture source has to be corrected or the problem returns. We repeat those four points wherever mold comes up, because each of them is routinely omitted at the point of sale.
Review schedule
Pages are reviewed on a cadence set by how fast the underlying facts move and how much a reader stands to lose if we are out of date.
| Pages | Target cadence | Reason |
|---|---|---|
| Cost guide, cost calculator, and calculator methodology | Every 3 to 6 months, and whenever a major cost publisher updates its figures | Published price data is revised frequently and readers make spending decisions directly from it. |
| Scams page | Every 6 months, and whenever a new enforcement action is documented | The value of the page is the enforcement record, which grows. |
| Mold pages | Every 6 months | Highest potential for reader harm, and the area where sales pressure is most intense. |
| NADCA certification page | Every 6 to 12 months | Association guidance and verification procedures change without notice. |
| Method, process, and decision pages | Every 12 months | Underlying technical facts move slowly. |
| Glossary and facts reference | Every 12 months, plus immediately whenever a cited source changes | Other pages depend on these being stable and correct. |
| Policy pages | Every 12 months, or immediately on any change to how the site operates | These must describe what the site actually does today, not what it did last year. |
A review means opening each cited source, confirming it still says what we say it says, checking its date, and looking for anything newer that supersedes it. Anything less is not a review.
On review dates
We do not change a “last reviewed” date without an actual review. Refreshing a date to look current is a small lie that makes every other date on the site meaningless, and it is common practice in this category. Where a page shows both a review date and a last-updated date, the second means the content materially changed and the first means somebody checked the sources. They are not the same event and we do not treat them as one.
Corrections, and what happens when sources disagree
Errors are handled under the corrections policy: substantive corrections are disclosed on the page rather than silently edited. The mechanics of verification, including how we distinguish a page we actually read from a search result about it, are set out in the fact-checking policy.
What to do next
- Fact-checking policy — the checks these rules are enforced with.
- Editorial team — who applies them, and what we are not qualified to do.
- Facts and figures — the labeling system, applied to every figure we publish.
Sources & references
- U.S. Environmental Protection AgencyShould You Have the Air Ducts in Your Home Cleaned?Page last updated February 19, 2026Our tier 1 anchor source, including on health claims, mold confirmation, and moisture.
- National Air Duct Cleaners AssociationAir Duct Cleaning Cost and Time EstimatesUndatedIndustry guidance whose $450-$1,000 range matches EPA's and is therefore never counted as a second source.
- National Air Duct Cleaners AssociationAvoid Air Duct Cleaning ScamsUndatedIndustry guidance we cite on scope, mold claims made without inspection, and false membership claims.