Mold Inspection And Testing Overview: When, How, DIY, Who To Call, Cost?

Mold infestation is one of the more dreaded home problems. Allergies, musty smell, and even structural damage are all consequences of undetected mold infestation.

How to do mold inspection and testing? At first, it seems it’s the easiest thing in the world:

  1. Mold inspection: Check if there is mold present in your house.
  2. Mold testing: Use a home kit to test which kind of mold infests your house.

It’s true that you can perform mold inspection yourself. You are advised to call a professional mold inspection but in the end, mold inspection is basically looking for evidence of mold growth, and you can do that yourself (we’ll show you 8 steps how professionals do it, and you can do it as well).

Here’s the quick insight from the EPA that most mold inspection specialist should tell you:

“In most cases, if visible mold growth is present, sampling is unnecessary.” (EPA on Mold Inspection)

Visible mold is easy to detect. Anyone can detect mold as obvious as this:

mold in the wall

The problem is the invisible mold in the air, in the walls, under the couch, and so on. Mold inspection specialists have experience noticing festering mold infections. When certified, they are referred to as ‘Industrial Hygienists’ or IH for short.

Mold Inspection And Testing Roadmap

How to tell if you need a mold inspection yourself?

We’ll look at 8 scenarios (like buying a new house) when calling a mold professional makes sense. The added value of a mold inspection specialist is that he or she will be able to test the mold, and based on that, advise you about mold testing and mediation.

How much are you expected to pay for a mold inspection?

Mold inspection professionals are a subset of indoor air quality specialists. However, according to EPA, “EPA does not have a certification program for mold inspectors.” That’s why prices for mold inspection may vary quite a bit; from $250 to $1,000.

We’ll look at how the size of the home factors in the cost of mold inspection, and who to call to get a decent mold inspection for a fair price.

All in all, you can use this article as a roadmap for mold inspection & testing. We’ll look into what exactly professional mold inspection is, can you do it yourself (and how), how to tell if you even need one, who to call for mold inspection, and how much does mold inspection costs, and so on.

Here are all the things we’ll cover further on:

If you need to jump to any particular part, you can just click on the chapter above. Let’s start with the most basic question about mold inspection:

What Is Mold Inspection?

To answer what is mold inspection we first need to look at why we would suspect we have a mold problem.

Mold is invariably connected with water and high humidity levels. Mold infestation occurs when mold spores land on wet indoor surfaces.

Here’s the deal:

No wet surfaces = No mold.

In short, mold growth is always, in 100% of cases, associated with water.

“There is no practical way to eliminate all mold and mold spores in the indoor environment; the way to control indoor mold growth is to control moisture.” (EPA on Mold)

Water leakage and spillings are a major invitation for mold to set in a house. The most problematic ones are the localized high humidity areas we don’t notice; under the rug, in the walls, near the indoor flowers, and so on.

water leakage under window sill and mold growth detected
Every wet surface presents a mold spore landing ground, and can potentially lead to mold growth. Window sills, bathrooms, attics, basements are the most concerning areas.

Mold inspection is nothing more (or less) than going around the house checking for mold growth. EPA explicitly says that if we find a “moldy area less than about 10 square feet” in size, we can take care of the mold problem ourselves.

The quality of that inspection for mold really comes down to how thorough and experienced we are at noticing mold growth. That’s where specialized mold professionals come in:

Does Mold Require A Specialized Inspection?

No. Anybody can check for mold. There are quite a few advantages of hiring a professional mold inspector, however.

Everybody can notice water leakage and subsequent mold growth. As we’ll see in the section of ‘How To Do Mold Inspection Yourself’, a professional mold inspection specialist follows the same steps you can.

However, these guys have probably looked at 100+ houses. That’s the amount of experience that counts when noticing early mold growth in particular. In all fairness, if you are thorough enough, you can come close to their level.

Professionals are particularly well equipped for mold testing. As EPA puts it, “sampling for mold should be conducted by professionals who have specific experience in designing mold-sampling protocols, sampling methods, and interpreting results.”

For non-professionals, mold testing presents a much bigger challenge than mold inspection. Let’s look at how professionals conduct a mold inspection and how you can DIY mold inspection if you wish to:

How To Do Mold Inspection Yourself? (What Mold Inspection Professional Does)

Specialized mold inspection professionals have both training and experience. However, that doesn’t mean that you can’t follow the recipe for mold inspection yourself, and save yourself some mold inspection costs.

You will need a flashlight and tools to open up floor tiles or even walls.

Here are the 8 steps of what mold inspection specialists do when conducting a routine house check:

  1. Looking for evidence of past mold growth. Black mold, for example, grows particularly well in areas that have been wet for quite some time. Repeated leaking is the first thing you should be check in the first house sweep. Running boiler water, leaking piping, high humidity levels in the bathroom’s corners, basements, and so on. Fix runny water sources, prevent leakages, get a dehumidifier for the basement.
  2. Current obvious mold growth. Also a part of the first mold inspection sweep. Overview of visible areas, with a focus on areas where mold is more likely to grow. These include water-rich areas like all bathroom surfaces (notice black lines between the tiles), kitchen sink surfaces, and especially corners. You might not notice black mold (past mold growth) but smaller and less dark mold colonies.
  3. Check structural damage (wood + water). Localized wet areas are the worst. Take your tools and open up floor tiles, walls, crawlspace, window sills, and other areas where wood decay and water combine. These areas are prone to mold growth and mold inspection specialists always take them seriously. Wall cavities and floor tiles are especially problematic mold growth areas.
  4. Check ventilation. It’s not unusual to find mold in an air conditioner. All ducted HVAC systems need to be checked for mold. Where there is airflow, there are probably mold spores in that airflow. The problem with indoor airflow creators (air conditioners, heaters, air purifiers) is that they can quickly spread mold spores. When they land on something wet, you’ll have a mold problem. It’s important to check and eliminate those threats as soon as possible.
  5. Moisture-map the whole house. A visual mold inspection will not detect mold growth that’s too small to be seen by the naked eye. That doesn’t mean mold is not growing. Go through all the house and identify the moisture-rich or potentially moisture-rich area. Earmark them for mold testing later; collect samples and test if you have Aspergillus, Penicillium, or other kinds of mold growing there.
  6. Inspect air for mold. Mold is spread via airborne mold spores. When they land on water, the mold will start to grow. When doing a mold inspection, you should always test for airborne mold spores. If your indoor air is full of dangerous and proliferous mold spores, chances are that the moment when you’ll have a water leakage, you will almost immediately get mold infestation as well. To remove airborne mold spores, use air purifiers that are best for mold.
  7. Check house plants and their localized surroundings. House plants present perfect conditions for mold growth. In their immediate surrounding, house plants tend to increase humidity levels, making it easy for mold to fester. One way to fight this is to capture airborne mold spored with air purifiers, another is to use a dehumidifier (especially in the summer when humidity levels are above 60%).
  8. Note that not all mold is bad. If you spot a black spot on a wooden tile, it’s almost certainly a consequence of mold. However, some mold species like Ceratosystis and Ophiostoma do only that. Black mold, for example, is very dangerous and will most probably create structural damage to the woods, and anything below the wood. Not to mention that once black mold spores are airborne, they can land on any wet surface. After the mold testing, however, it important to differentiate between harmful mold (black mold) and harmless mold (Ceratosystis and Ophiostoma, for example).

Where Is Mold Most Frequently Found?

Areas that are most likely to host mold are:

  • Bathroom walls and walls near a kitchen sink – especially check for black lines alongside ceramic tiles.
  • Other walls (especially unfinished ones) – check at the base, in the corners, and alongside any visible cracks in the walls.
  • HVAC vents that handle a lot of airflow – check for mold in air conditioners and heating vents.
  • Basements with high humidity levels – mold loves basements in particular.
  • Cavities between drywall and wall foundation – there a slim sweet spot that always warrants mold inspection.
  • Damp attic spaces – after the rain, the air in attics can be very humid and is more likely to spur mold growth.

All steps of checking for mold need a careful (and experienced) eye.

Example: You might think there’s no way mold is festering under floor tiles. A mold inspection specialist has probably looked under floor tiles in 100 houses, and 14 of them had mold growth here.

That’s just the advantage of experience specialists have. Another one is that they can conduct mold testing once they suspect mold is present in the house:

How Does Mold Testing Differ From Inspection?

Most testing is not the same as mold inspection. Mold inspection is just a visual assessment of the presence of mold.

Mold testing, by contrast, is the identification of individual species of mold that may be growing in wet parts of our house. Basically, a mold professional takes samples with a cotton swab from all the places where mold definitely grows and from all spaces where mold could potentially grow.

Testing air for the presence of mold spores is also advisable and included in most mold testing procedures.

D. M. Kuhn et al have conducted an extensive study (published in Clinical Microbiological Review) about which species of indoor mold and toxigenic fungi are present in damp buildings. Here are some conclusions:

“A host of mold species have been isolated from damp buildings: the most frequently isolated in one study were Penicillium (96%), Cladosporium (89%), Ulocladium (62%), Geomyces pannorum (57%), and Sistronema brinkmannii (51%).” (2003 Indoor Mold Study)

Here are these findings presented in a graph:

mold species found during mold inspections in building with high humidity levels

As you can see, finding various species of mold is very frequent in damp buildings. Specialists might also refer to these mold species as ‘black mold’, ‘white mold mildew’, or ‘pink mold’, depending on the overall color of the mycelium colonies.

When you suspect you have a mold infestation, it’s best to conduct a mold inspection & testing all-in-one. There are two ways of doing that:

  1. Call a mold infestation professional: he or she will take samples to the lab, and thereby analyze the mold in your house.
  2. You can DIY installation and buy an at-home mold testing kit.

Of course, testing the mold in your home yourself can be done, but you’ll also need additional knowledge about the nature of the mold species. Some are harmless, others are toxic and can present a danger to you and your family.

Let’s look at how who actually needs to conduct a mold inspection:

How To Tell You Need A Mold Inspection?

Chances are that when you most need a mold inspection, you won’t call a professional to do it, or even do it yourself.

That’s because we only think we need a mold inspection when we can already see the mold. As we have seen, EPA advises that when you can already see the mold, the mold inspection is unnecessary.

The damage is already done, and we need to begin actively fight mold infection with mold mediation techniques.

That’s why it’s so important to detect mold growth before it grows too much. To help you out, here are the 7 most likely scenarios when you need a mold inspection:

  1. If you see mold in one spot, you have a mold problem. It has most likely spread through your house. Mold inspection is a wise choice to detect all the mold growth, moisture-map your house, and test for dangerous species of mold.
  2. Do you experience allergies or allergy-like symptoms in a particular room? According to the EPA, “Potential health effects and symptoms associated with mold exposures include allergic reactions, asthma, and other respiratory complaints”. If you experience these kinds of symptoms in a certain room, it’s likely you have a mold infestation and mold inspection is warranted.
  3. When you’re buying a new house. Without a mold inspection, there is no way of knowing if there is mold in the new property you’re buying. Structural damage can be a result of undetected mold infestation; which can influence the price of the new home. It’s recommended to order a mold inspection prior to buying a property – just to be safe or even to negotiate a lower price if mold is detected.
  4. The musty smell of mold. If you can smell mold, that means you probably have a mold problem. The amount of mold growth to produce enough odor for you to smell it can be substantial. The only sure way to find if you have mold in your home is to call a mold inspection specialist.
  5. You have leakage for more than 24 hours. Water is life for mold. If you have a leaking pipe or a spillage, and the water was undisturbed for more than 24 hours, there is a higher chance that mold has settled in. If it has, it will start multiplying, even if you’ve fixed the leakage. You will notice symptoms – potential allergies, mold smell, or even start to see black stains – if you want too long. In such a situation, it makes sense to start with a mold inspection and testing.
  6. Unoccupied houses. If a house or an apartment was unoccupied for a longer period of time, chances are mold started growing. These kinds of mold problems can be visible with a naked eye; together with structural damage, unfortunately. Nonetheless, there is no way of knowing if any leakages, spillage, or even high humidity summers were the cause of mold growth. To check everything is OK, you should check for mold before moving in, or before starting with renovations.
  7. Conducting a full indoor air quality inspection. Obviously, we all want to breathe high-quality air. When we start to investigate how to increase indoor air quality, we usually begin with a full assessment. Full assessment should include airborne mold spored sampling and testing. Based on that, you can decide if you only need an air purifier (you can check the best air cleaners here) or should you also lower your indoor humidity levels to prevent mold growth.
  8. After mold remediation. How to really know if mold remediation worked? Mold inspection and testing, of course. After mold remediation, it’s recommended to check how well mold was removed, and what to do in the future to avoid mold resurgence.

It is also useful to know when you don’t need mold inspection at all. Having house plants might create a localized high humidity space but that does not warrant a full-house mold inspection, for example.

Spilling a glass of water and leaving it overnight also won’t create a mold problem.

When summer humidity kicks in, you don’t call a mold inspection specialist. Rather, wait for the symptoms if mold is starting to grow (very unlikely), or even use preventive measures by using a dehumidifier to lower relative humidity levels.

The most economically consequential concern in relation to mold inspection is when we’re buying a new property. Let’s talk a bit more about buying new real estate:

Should I Get A Mold Inspection When Buying A House?

Let’s say a house costs $500,000. If, however, a mold inspection specialized would find a years-long undetected mold infestation that has likely negatively affected the structural integrity of the whole house, that house might not be worth more than $400,000.

That’s a $100,000 you might be unknowingly cheated out of. The interesting thing is that both you and the seller don’t really know if there is a mold problem and not. Mold can be hidden under wooden surfaces, or even in the walls.

It’s not likely you’ll have to pay more than $1000 for a thorough mold inspection, as we’ll see in the next chapter.

The cost of the inspection is usually insignificant compared to the value of the property you’re buying. It’s also insignificant to the potential change of price of the real state that might occur, in favor of the buyer.

Here the deal:

In almost every case, it makes financial sense to hire a mold inspection before buying a home.

You will know if you have mold problems, and it could potentially lead to a better deal on the house if the mold problems were to be uncovered.

Now, let’s talk about the prices companies specialized for mold inspection offer:

How Much Does A Mold Inspection Cost?

As we have previously seen, mold inspection is nothing more (or less) than a visual check for mold. Everybody can do it. However, people with experience are the best at noticing hidden mold, and they are better trained and equipped for testing than an average homeowner.

According to Home Advisor, the national average professional mold inspection costs about $650. That figure can vary quite a bit, depending primarily on:

  • State. California will have higher prices of mold inspections, for example.
  • Square footage of a home. Bigger homes need more time to inspect, hence higher prices.

Secondarily, the costs of mold inspection also depend on how serious a mold problem you have.

For most homes, you can expect to pay anywhere between $250 and $1,000.

average cost of mold inspection with low and high end interval

A professional mold inspection services for huge real estate can surpass $2,000, but that’s very unlikely. If you can find a specialist for less than $200, it’s advisable to double-check the credentials and references they might have.

With a little time and some research, you can also check for mold yourself. DIY testing kits for mold are also available for less than $100.

Most often, however, homeowners do prefer professional help. Here are a few things to have in mind when contacting and contracting a mold inspection company or an individual specialist:

Who To Call For Mold Inspection?

EPA specifically states that they do “not have a certification program for mold inspectors or mold remediation firms”. Everybody, even people who have not made 100+ house mold inspections, can call themselves ‘experts’. That presents a kind of a ‘Wild West’ problem.

Some states have certification and training programs. When calling companies or individuals for mold inspection, do beck for what certification or training they may have. ‘Industrial Hygienists’ or IH is a certification that is credible, for example.

Other questions you should be asking your future mold inspector should cover (as advised by the EPA):

  • Qualifications. For both individuals and companies.
  • Number of mold checks per month and year. Specialized professionals should find no lack of work, and are expected to perform at least 100 mold inspections per year.
  • Mold sampling and testing practices. If they tell you they can smell Penicillium spores from a mile away, you should best steer clear of them. Specific tests, mold species, and so on are expected in this answer.
  • Cost, hourly rate, and payment terms. You have a pretty good idea of how much it should cost ($1000+ is almost always too much). That’s why asking about mold infestation hourly rate is a good idea. Also beware of contractors that need a 100% upfront payment. 50% before the inspection and 50% after the inspection is the industry standard.

Hopefully, with all this, you’re well equipped with the mold inspection and testing knowledge.

You can figure out if you need a mold inspection, and have some idea who to call, or at least what to ask mold inspection contractors.

As always, you can also do the whole thing yourself. Having the mold inspection skill set is always useful, and you can help other people out as well.

2 thoughts on “Mold Inspection And Testing Overview: When, How, DIY, Who To Call, Cost?”

  1. Great article! very informative and on point! Mold professional should be able to explain the problem to you in a way you can understand and help you know what needs to be done to fix it.

  2. I agree with you that contractors who require a 100 percent upfront payment should be avoided. I need someone to clean up some mold on my roof because I can’t handle it alone. Thank you for providing mold inspection information, and I hope to find a cleaning service that can assist me with it soon. Thank you for writing this!


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