Home/Do I need a test?
Free triage · no email requiredDo I actually need a mold inspection?
Reviewed October 2026 · London, Ontario
You need a mold inspection when you smell must but cannot see the source, after a leak or flood, when someone else needs proof (a buyer, a landlord, a tenant or an insurer), or to confirm a removal worked. You usually do not need one for a small patch with an obvious cause that you are going to clean. Answer four quick questions and we will tell you honestly whether testing is worth it for your situation, and which kind, or whether you can skip it. We would rather send you away than sell you a test you do not need.
How this reads your answers
- A dispute, sale, insurer or clearance almost always needs an independent test, because the value is the documentation.
- A musty smell with nothing visible or a post-flood concern points to air sampling, since the question is what you can't see.
- A small visible patch with a known cause and no documentation needed often does not need a lab test, and we will tell you so.
- A sensitive occupant plus extensive growth raises the priority and is also a reason to talk to a doctor, separately from testing.
This is guidance, not a diagnosis. Only lab-analyzed sampling gives an actual answer, and health questions belong with your physician, not this tool.
Signs you need a mold inspection
The triage above reads your answers. These are the signs behind it, the ones that make a mold inspection in London, Ontario worth paying for:
- A musty smell with nothing visible. The most common reason growth is hidden: behind finished basement walls, under flooring, or inside a wall next to a slow plumbing leak.
- Staining that comes back after you clean it. The moisture is still there, and the visible part may be the edge of something larger.
- A leak or flood in the last few months. Drying stops new growth. It does not tell you what grew while the materials were wet.
- Frost or dark speckling on attic sheathing after a London winter, usually a bath fan or blocked soffit problem.
- Someone else needs to rely on the answer: a buyer inside a condition period, a landlord or tenant, an insurer, or a contractor about to quote.
- A removal job just finished and you want an independent check before the walls close.
When you can skip it
A patch smaller than about one square metre, on a surface you can clean, with an obvious cause such as shower condensation or a window that sweats, does not need a lab. Health Canada says that in most cases there is no need to measure the mould in your air or to name the species. Clean it, fix the moisture, keep indoor humidity between 30 and 50 percent, and watch whether it returns. Our mould removal guide sets out Health Canada's small, medium and large categories.
Mould testing or a full inspection?
Mould testing is the sampling and the lab work. An inspection is the visit around it: finding the water, deciding where a sample will actually tell you something, and putting it all in a written report. If you only want one visible patch named, a single-patch identification is $250 to $400. If you want to know where it is coming from and how far it goes, that is an inspection at $300 to $600. The full breakdown is on the mold inspection cost page.
Health questions go to a doctor
No test can tell you whether mould is making a particular person ill, and the Middlesex-London Health Unit notes there are no official safety limits for mould in indoor air. If someone in the home has symptoms, see a physician. For general questions about mould and health in London, the health unit takes calls at 519-663-5317.
Common questions
Do I always need a professional mold test?
No. A small, clearly visible patch with a known cause that you are simply going to clean, and where you do not need documentation, often does not need a lab test. Testing earns its cost when the extent is unclear, air quality is the concern, a dispute or sale is involved, or you want proof before paying for removal.
I can see the mold. Why test it?
If you can see it, smell it, and already plan to remove it, a test still identifies what it is and gives you a documented before-and-after. If you are unsure how far it goes or whether the air is affected, that is exactly what a test is for.
Should I see a doctor or get a test?
They answer different questions. A doctor addresses symptoms and health; a mold test identifies what is in your home and whether the air is affected. If you have worrying symptoms, see your physician. This tool is about the home, not your health.
What is the difference between mould testing and a mold inspection?
Mould testing is the sampling and lab analysis: it names what is growing and compares indoor air with outdoor air. A mold inspection is the whole visit around it: the walk-through, moisture readings to find the water, the decision on where sampling actually helps, and a written report. Most people who need one need both.
What are the signs I need a mold inspection?
A musty smell that will not go away, staining that returns after cleaning, a leak or flood in the last few months, condensation on attic sheathing, a home inspector noting moisture during a purchase, or a dispute where you need an independent document.
How much does a mold inspection cost if I do need one?
In London, $300 to $600 for a residential inspection with accredited-lab analysis, or $250 to $400 to identify a single patch. The price is confirmed before booking.
Is this tool a substitute for an inspection?
No. It is a quick way to decide whether an inspection is worth it for your situation. The inspection itself, with lab-analyzed samples, is what produces an actual answer.
Rather just talk?
(548) 290-9788Tell us what you are seeing or smelling and we will tell you whether a test makes sense.
- Testing and inspection only, never removal
- Accredited-lab analysis, outdoor baseline
- Results in a few business days
Get a straight answer
No hard sell. Tell us the situation and we will tell you whether you need a test, and what it would cost.