Mould testing means a sample of air, a surface or a piece of material goes to a lab, and in most homes you can skip it. Health Canada does not recommend testing the air for mould in most situations, because the result cannot predict health effects and says little about the cause.
A careful visual inspection that finds the water usually tells you more. Testing earns its fee in two places: finding hidden growth when a musty smell or a history of leaks has no visible explanation, and checking a large removal once it is done.
We are a removal and cleanup crew, not indoor air quality consultants, and we do not run clearance sampling.
On this page
What a mould test is, and what each sample tells you.
A mould test is a sample taken in your home and read by a lab. Mold Inspection Canada, which publishes a national guide to 2026 inspection prices, sorts samples into three kinds, and each one answers a different question.
An air sample is collected by a machine and examined under a microscope. Health Canada calls this a non-viable air test, because the spores are counted without being grown in culture, and it can pick out specific indicator mould types. Mold Inspection Canada's standard inspection takes one indoor sample per affected level and one outdoor control, and compares the spore counts between the two.
A surface swab is taken from growth you can already see, to identify the species. A bulk sample is a piece of the material itself, drywall, insulation or carpet, sent to the lab intact. Mold Inspection Canada prices each extra sample on top of an inspection: $80 to $150 for air, $50 to $100 for a swab and $75 to $150 for a bulk sample.
None of these is our price.
None of the three tells you how much material has to come out. That comes from looking. Health Canada's guide says a systematic approach based on a thorough visual inspection is usually more effective than relying on extensive air, bulk or swab testing.
Its inspection is a walk through every room, the attic, the basement, crawl spaces and storage spaces, looking for stains, peeling paint, warped wood, a white powdery crust on masonry, and the leak behind them.
Why most homes can skip the air test.
In most situations, Health Canada does not recommend testing the air for mould. Its guide gives two reasons: an air test does not provide information that can predict health effects, and it often offers little information on the cause of the mould damage.
Its residential indoor air quality guideline for moulds explains the first reason. There are too many mould species and strains growing in buildings, and people react to them too differently, to set exposure limits. Without exposure limits, the guideline says, results from tests for fungi in the air cannot be used to assess risks to the health of the people living there.
The same guideline makes two recommendations: control humidity and repair water damage to prevent mould growth, and clean thoroughly any visible or concealed mould. It says both apply regardless of the mould species growing in the building. So if you can see the mould, a test mostly confirms that it is there. What you need next is where the water is coming from and how far the damage reaches.
When a mould test is worth paying for.
Health Canada names the case where a test helps. Where concerns remain unexplained after an inspection for dampness and mould, especially with a history of flooding, roof leaks or pipe leaks that may have reached wall cavities, a qualified professional may recommend a non-viable air test. High counts of those indicator moulds may help point the professional to hidden problems inside wall and ceiling cavities.
Health Canada's guide also deals with smell. It suggests rating mouldy or musty odours in each room as mild, moderate or strong, and acting at once, with professionals, on any room rated strong. Where a strong, musty odour comes with no clear sign of water damage or mould, it suggests consulting a professional about hidden mould inside walls and ceiling or floor cavities.
A flooded basement is that kind of history. The City of Ottawa lists melting snow from spring runoff, and heavy rain, leaking through cracks and joints in foundation walls and floors among the causes of basement flooding. If yours has taken water, our guide to a flooded basement in Ottawa covers the first 48 hours, which decide whether there is hidden mould to look for at all.
A test is not worth paying for when the mould is visible and you already know the leak. Health Canada's size chart decides who removes it. Three patches or fewer, totalling one square metre or less, is small, and may be cleaned up using proper procedures and protective equipment. A single patch larger than three square metres needs a professional assessment and cleanup.
Testing versus removal: who does what.
Two different jobs share the word mould. A tester or indoor air quality consultant inspects, takes samples and writes a report. A remediation crew contains the area, removes what cannot be cleaned and dries the structure. On a large job, Health Canada advises a separate company for the check at the end.
For any major project, Health Canada advises a written outline before work starts. It should set out the project scope, including any sampling and the results required, the documents you will receive, the quality control, budget estimates and fee schedules, a schedule that accounts for the health and safety of the people living there, and whether a post-remediation inspection by an independent third-party consultant is expected.
Our side of it is the removal. We trace the mould back to its moisture source, size the area against Health Canada's chart, contain it, take out what has to go and haul it away, and the method is set out on our page about mould removal in Ottawa.
We are not indoor air quality consultants and we do not run clearance sampling. Where your job needs a separate firm, we will say so rather than quote around it.
If the mould started with a leak or a flood, the water comes first. Our water damage restoration page covers the drying, and Health Canada's guide says mould will begin to grow in an area with excessive moisture within 48 hours.
Clearance testing after a large removal.
A clearance test is the check after the work. Health Canada says that where extensive cleanup involves structural elements like walls, the company doing it should recommend you consider hiring a separate company to perform a post-remediation clearance study, to make sure the mould has been correctly removed and the moisture addressed.
The separation is the point. Health Canada's outline for a major project describes that inspection as one done by an independent third-party consultant. Mold Inspection Canada lists post-remediation clearance among the reasons to take an air sample.
On a small patch you clean yourself, the check is simpler: does it come back? Health Canada's guide says mould that comes back after cleaning is usually an indication that the source of moisture has not been removed, and that it is time for professional help.
How to hire a mould tester, and read the report.
Ask what decision the result will change. If the mould is visible and the leak is known, the honest answer is often none, and the money is better spent on the removal and the repair.
Ask about the lab. Health Canada's guide says that where laboratory work is involved, the lab should be accredited to the ISO/IEC 17025:2017 standard by the Canadian Association for Laboratory Accreditation, the Standards Council of Canada, the American Industrial Hygiene Association or an equivalent recognized body.
Ask for the approach and the fees in writing. Health Canada advises asking a professional for their general approach to the problem, finding out what criteria will decide between testing and remediation strategies, and getting estimated fees for each phase, including what follow-up investigation may cost.
Know what a free inspection is. Some Ottawa companies that remove mould advertise a free inspection. Mold Inspection Canada describes a free inspection as a quick first look, useful for triage, and not a substitute for a full inspection with lab results when you need documentation for an insurance claim or a mortgage closing.
On price, Mold Inspection Canada puts a typical inspection in Ottawa, Kanata and Gatineau at $250 to $400, with lab results in 48 hours. Our guide to what mould removal costs in Ottawa sets inspection prices beside two companies' published removal prices.
Then read the report against the house. Indoor spore counts are read against the outdoor control, which is why a standard inspection takes one. A report worth paying for says where the growth is, how far it reaches and what is feeding it, because the removal is priced on the size of the affected area and the containment that size forces.
Which test answers which question.
The middle column draws on Health Canada and on Mold Inspection Canada's 2026 inspection price guide, a company's page that is named but not linked. The right-hand column is Health Canada's own guidance, from pages read on 2026-10-14, and linked at the foot of this page.
| Test | What it is | What Health Canada says |
|---|---|---|
| Visual inspection | A walk through every room, the attic, basement and crawl spaces, looking for growth, stains and the water behind them. | Start here. A thorough visual inspection is usually more effective than extensive air, bulk or swab testing. |
| Non-viable air sample | Machine-collected air examined under a microscope, read against an outdoor control. | Not recommended in most situations. A professional may recommend one where concerns remain unexplained, to find hidden growth. |
| Surface swab | A swab of visible growth, sent to the lab to identify the species. | The visual inspection usually tells you more than extensive swab testing. |
| Bulk material sample | A piece of drywall, insulation or carpet sent to the lab intact. | Porous materials often cannot be properly cleaned and must be discarded. |
| Species identification | Lab confirmation of which mould is growing. Mold Inspection Canada lists it at $100 to $200 extra. | Its recommendations apply regardless of the mould species growing in the building. |
| Post-remediation clearance study | A check after removal that the mould is gone and the moisture dealt with. | Recommended from a separate company after extensive cleanup involving structural elements like walls. |
Usually not. Health Canada does not recommend air testing in most situations, and its advice on cleaning up mould applies whatever the species. If you can see the mould and you know where the water came from, the next step is sizing the area against Health Canada's chart. A test helps where a musty smell or a history of leaks has no visible explanation.
Mold Inspection Canada, which publishes a national price guide, puts a typical inspection in Ottawa, Kanata and Gatineau at $250 to $400, with lab results in 48 hours. Its standard tier includes a visual inspection, one indoor air sample, one outdoor control and the lab analysis, and it lists each extra air sample at $80 to $150. Those are its figures, read on 2026-10-14, not ours.
As a first look, it can be. Mold Inspection Canada calls a free inspection a quick first look for triage, and says it is not a substitute for a full inspection with lab results when you need documentation for an insurance claim or a mortgage closing. After a large removal, Health Canada's advice is that the clearance check comes from a separate company.
Rarely. Health Canada's indoor air quality guideline says its recommendations, control humidity, repair water damage and clean the mould thoroughly, apply regardless of the mould species growing in the building. Mold Inspection Canada lists species identification as a $100 to $200 extra. Colour is not a diagnosis, and the species does not change what has to come out.
A check after removal that the mould was correctly removed and the moisture addressed. Health Canada says that where extensive cleanup involves structural elements like walls, the company should recommend you consider a separate company for this post-remediation clearance study. We do not run clearance sampling, and on a job that size we will tell you so.
Mold Inspection Canada says a do-it-yourself kit answers only whether there is mould, and does not identify its species, source or extent. Health Canada's starting point needs no kit: walk every room, the attic, basement and crawl spaces, and look for stains, peeling paint, warped wood, a white powdery crust on masonry, and musty odours.
Soap and water, not bleach. Health Canada says to scrub hard surfaces with a cloth and an unscented soap solution and dry them completely and quickly, and not to use bleach to clean up mould. Porous material such as carpet and fabric often cannot be properly cleaned and has to be discarded. Fix the moisture first, or it grows back.
We remove mould across Ottawa and Gatineau: containment, tear-out of material that cannot be cleaned, drying and the haul-away. Send photos to (613) 852-4059 and we will tell you which of Health Canada's size bands it falls in, and whether it is a job you can do yourself.