Mold is easy to understand. It needs moisture and food to grow.
You don’t have to feel uncertain, afraid, or helpless when it comes to the health of your home.
Instead, become empowered — through awareness of your building, how it interacts with moisture, and what to do about it.
Explore this article
1 — Explore The Building
2 — Where Water Intrudes
3 — Inspect The Whole Building
4 — Extra Tools To Find Mold
5 — Certified Building Biologists
6 — Mold Testing
7 — Stop All Water Intrusion
8 — Assess Where You Are
9 — Small Problems
10 — Large Problems
11 — The Path Forward, Trust Yourself
12 — If You Remediate
Explore the Mold section
Confusion disappears when we understand how buildings work.
A calm, clear mind is best. Whatever happens, you can handle it.
Inspect every inch of your home — looking for signs of moisture or water intrusion.
Become a Do-It-Yourself Building Inspector
You don’t need all the answers immediately, and being unsure about something is okay.
Instead, learn the process of inspection.
As you look at a building, use your imagination. How does water interact with this structure?
- Where does water come from?
- Where does it go?
- How does moisture leave the house?
It can be shocking how easily water finds its way into buildings.
Roofs must be completely watertight.
Even slightly loose shingles, nails, and screws let water into the building.
Look for misaligned shingles or signs moisture in the attic.
Around the Foundation
Proper drainage around a building is essential for inhabitants’ health — and the building’s.
When drainage is poor, water collects next to buildings, unable to escape. If allowed to linger, moisture will always find a way inside.
Instead, water should be directed far away from buildings, and not be allowed to sink underneath the foundation.
Proper grading around buildings is critical for drainage. The ground must slope away from the building, about 8 inches for every ten feet.
This drainage water found its way under the house’s foundation, potentially destabilizing the slab or humidifying the crawl space.
Gutters should empty onto a splash block, not the ground. A splash block distributes water further fromthe house.
The more plumbing in a building, the more likely a leak will develop inside one. More pipes means more opportunity for a problem.
Be sure to monitor sinks, showers, and toilets regularly. Look for any signs of leaks — bubbling, cracking, and musty smells.
Windows need a tight seal.
Improperly installed, they can let water inside the walls.
Appliances Use Water
So many appliances use water.
Leaks and clogged drainage lines present risks for water intrusion into your home.
Mold can also grow inside the housings and pipes, especially when unable to air out and dry.
Condensation is created when air is rapidly cooled.
Condensation in an air conditioning inut goes into a drain, which can become moldy due to the moisture. Cold evaporator coils will get moldy, too, if not cleaned yearly — and protected with UV lights.
Get to know your HVAC system. Compare it to how other buildings’ systems are. Look inside the unit if possible. Observe the filters and the coils. Smell the air that comes from vents. Open floor vents and look inside. Notice thermostat settings.
Become aware of its health status.
A humidity meter (cheap on Amazon) can be a valuable insight into how much moisture your HVAC system is being exposed to.
Explore every room at close proximity.
Look in corners, where walls meet the floor and ceiling, and inside closets and cabinets.
As you walk through the building, imagine how water might arrive at any location inside the house.
Don’t forget that humidity above 60% represents enough moisture to substantially feed mold.
Nooks & Crannies
These complete inspections should be routine — performed at least monthly.
Use Your Nose
A moldy smell often tells the whole story.
When determining how healthy a building is, your nose can often identify how big a problem is.
In other words, if you smell a problem — there is one.
Your nose can also help you find mold in a room: explore cabinets, corners, closets, air conditioners and appliances.
After all, if there’s a musty smell, there’s almost certainly mold growth somewhere.
Remember that mold isn’t always visible — it’s often tucked away inside walls and ducts, or under flooring.
But if you can smell it, it’s there.
Hibernating, mold can still release toxic fumes and spores long after the leak has been fixed and the mold has dried up.
It’s possible and even common to smell mold that hasn’t been actively growing in some time — yet still affects the health of the home.
Trust your nose. It could be your most reliable tool.
Anosmia is the scientific name for a weakened sense of smell.
Losing a sense of smell is often related to weakened health.
What causes anosmia?
- Diseases involving organ injury and energy deficiency
Mold affects the body in terms of allergies and infection.
Losing your sense of smell is one sign of mold exposure.
Use Your Eyes
Mold is often unseen — hiding inside appliances, walls, attics, closets, flooring, & cabinets.
On the other hand, water moves — it soaks through materials. If. a leak gets bad enough, its chances of becoming visible rise.
When mold is often not easily seen, it can escape our attention and grow exponentially into a massive problem.
Therefore, to successfully stop mold, the location and extent of moisture intrusion must always be identified.
Humidity enables mold growth — especially in crawl spaces and garages — usually made worse by poor airflow (trapped air). In trapped spaces, humidity enters a space, moisture in the air rises, and then can’t leave.
Too, summer climates often have humidity in the 70%-90% range. Air doesn’t even need to be trapped to encourage mold growth when humidity is this high.
Observe all of these spaces. Look with your eyes for any sign of fungal growth. Feel the air and measure it with a hygrometer. Search for musty smells.
Mold rarely stays in one place — it spreads.
Keep looking, everywhere.
Infrared cameras can see surface temperature — and therefore can see where moisture lies.
If water is present inside a wall, the wall will be cooler, and an infrared camera will show less heat radiating off a wall.
(Water always soaks up heat — it’s a heat sink — meaning, water traps heat, so the heat never reaches the IR camera).
Purchase an Infrared Camera
Cheaper models run from $75-$350.
Higher-end models are in the thousands.
The cheaper models are sufficient to keep track of your home and other buildings. A Building Biologist will have a top-shelf instrument.
Moisture meters are cheap and simple to use.
Simply hold the meter up to a wall and check the moisture content of this area of the wall.
Readings above 12% suggest potential moisture issues, and above 17% confirm moisture problems.
General Tools MMD4E Digital Moisture Meter
Certified Building Biologists
Your best guide for home inspection?
A certified Building Biologist will have rigorous training, high-quality instruments (including an infrared camera), and will be able to help guide you through the process of determining causes, solutions and severity of issues.
Professional-grade air quality tests can be performed (of much higher value than store-bought tests and can include other contaminants besides mold), non-visible moisture and leaks can be detected, and even EMF testing (which can be incredibly important).
Ultimately, however, your best guide is you — you live in your home on a daily basis, and you’ll need to be in charge of any remediation work done on the house.
If you don’t make sure the job is done right, it probably won’t be.
Building Biologists Don’t Do The Remediation
While a Building Biologist may be highly adept at solving moisture issues, it will be construction crews who do the work on your house.
You’ll need to find a contractor who understands how to remediate and remove harmful mycotoxins and spores without spreading them.
A remediation job can be a difficult, complex, and expensive process. Trust yourself, how you feel, and stay on top of the process.
Micro-manage it, even — do not feel like you’re bothering the contractor. Be upfront about what you need, get a signed contract for the work, and monitor the work yourself. Be selective about who you hire.
Mold testing can be a legitimate way to identify species of mold in your home.
It can also be an unreliable, expensive endeavor.
Get a cheaper HERTSMI test right away — if you want.
- Only tests for 5 molds.
- Cost: ~$190
More extensive and expensive.
- Tests for 36 molds.
- Cost: ~$290
Woe-fully incomplete test.
- This only gives you a tiny snapshot of what’s happening in your building.
- Likely to seriously underestimate any mold issues.
You can buy these cheap kits at Home Depot.
- These tell you very little.
- If mold grows incredibly fast, this might indicate a severe problem.
- Otherwise, this test is of little scientific value.
Order a HERTSMI or ERMI test –> here.
Mold Tests Are Hardly Perfect
No test — even the best ones (ERMI, HERTSMI) is conclusive of anything.
There will always be room for error with any scientific test. What’s more, tests only show a snapshot in time rather than an entire picture.
Testing surfaces only shows what was on a specific surface on the day of the test.
Too, it’s possible for some spores to be airborne, or follow airflow patterns to a different surface in a room.
It’s also possible for cleaning to interfere with surface tests.
Testing the air only reveals the contents of the air during the test period. Varying humidity levels can skew air test results. Air tests won’t reveal what is on surfaces.
The Limits Of Testing
- No test is can find spores resting behind the toilet or inside walls.
- Tests don’t identify the location or size of mold growth. Tests likely won’t reveal problems that are only beginning, in their infancy.
- Mold’s toxic odors often seep through the walls while the spores remain behind walls, hidden from mold tests.
Mike Schrantz, Expert
Mike Schrantz owns and operates Environmental Analytics, an environmental consulting firm. Here’s a quote of his from an interview with Chris Kresser.
Schrantz is a knowledgeable, data-driven expert. He is performing a service for a fee, and he doesn’t want to depend on guesswork — so he uses testing, reports and data. “I think, maybe…” doesn’t work so well when you’re charging people lots of money and guaranteeing results.
That said, even a super data-driven expert like Schrantz says that focused, motivated, curious observation is (to some extent) more important than testing.
Do tests have a place? Sure. Absolutely. More information is always good, as long as we understand that mold testing results are simply a limited snapshot of one place at one point in time.
But the best information comes from you.
Walking around, poking around, looking with your eyes, smelling with your nose — using your awareness.
The Chris Kresser Mold Story
The internet-famous acupuncturist and health blogger, Chris Kresser, bought a 1920’s house in the (very-humid) Bay Area a few years ago.
They suspected mold and decided to test for it.
Chris hired Mike Schrantz, who flew in (multiple times) from Arizona. He did extensive testing, but the tests didn’t show much mold, only slightly elevated spore counts. They wanted to explore more — to make sure the house was safe — so they cut holes into walls and removed some sections of walls. Testing still didn’t show much.
It was only a few rainy days later that Chris noticed one of his walls was wet to the touch (and bulging a little) next to a window. That’s a MAJOR sign! So they tore out the wall and found the window had been leaking.
Inside the wall, they noticed mold growing above the window — which indicated moisture above the window. Looking higher up, they found a failed gutter system that was pouring water into the walls — and mold was everywhere.
Finally — after all moldy materials had been removed and the area scrubbed clean, they retested… and failed the ERMI test.
On a blind hunch, they guessed the cleaning crew had not cleaned very well — simply because the ERMI test employee saw more dust on the floors than he’d expect after a thorough cleaning.
So they cleaned more thoroughly and tested again, and their new ERMI score “passed.” (Now, even this latest ERMI score doesn’t show what spore counts look like after, say, 12 months. It’s possible they didn’t fix the problem and more water intrusion will happen soon. It’s also possible the mold VOC’s permeated the house to an unhealthy level, even if mold growth has been entirely stopped).
Said Kresser: “In all of the testing that we did, the testing just pointed to a problem, but the place that ended up being the most significant issue was something that was not identified with any of the previous testing and that we actually found by good old fashioned visual observation.”
Don’t Obsess Over Tests
It’s easy to become obsessed with testing mold counts.
Don’t. Instead, trust your nose and how you feel and use tests as an adjunct. If the air doesn’t smell fresh, that’s 50% of what you need to know. If you feel poorly, that’s almost the other 50%. Tests aren’t always reliable, and no two people will react identically to the same result, anyway.
If you have the money to perform tests, yes. Do multiple. If you’re remediating, yes — do many rounds of tests.
But don’t trust them implicitly. Don’t wait around for months wondering, waiting — thinking someone is going to swoop in and tell you what to do. Instead, be vigilant. Be curious. Get to know your building. Inspect it frequently. Understand it. Take steps to improve and protect your health now.
Greg Muske’s Experience
Greg Muske of biotoxinjourney.com is a wonderful resource for the mold community, and he is very pro-testing. He is like many mold advocates, experts, and doctors — focusing a large majority of their energy on mold avoidance.
“My house is a perfect case in point. We’ve now spent over 2 years and $8,000 doing all of the above mentioned tests numerous times (7 ERMI, 40+ spore traps, a couple dozen Petri dishes, 2 VOC tests, and one mold-dog) in an effort to find out if the new home I built has mold issues. We’d do a round of tests. I’d tear into the house even more. Nothing would be found. I’d then go back and re-evaluate the test method before testing in another way. Round and round and round we went. None of the tests seemed definitive. Talking with four different professional inspectors often left me with more questions than answers.”Greg Muske
“You’d think that with this arsenal of tests along with the expertise of a mold inspector that you could tell if a building is moldy or not. Unfortunately, sometimes it’s not always so straight forward.”
If you need to take action — even major action — mold testing can help confirm what you’ve already realized via your own inspection and intuition.
This website is designed to help you get there: fully aware, equipped, and ready to act.
Stop All Water Intrusion
A mold test won’t show a water leak. Moisture intrusion must be discovered by you.
This means homeowners and renters alike need to be aware of all potential sources of water intrusion — whether from pipe leaks, rain fall, flooding, or humidity.
Active Leaks Must Be Stopped
Identify all areas of excess moisture. Get all leaks fixed immediately!
Do not wait another day to get a leak fixed. If you have to turn off water to a pipe, do so right away.
Use fans and dehumidifiers to dry the area as quickly as possible.
Heat lamps can help dry materials without blowing mold spores around (but be careful, they’re super hot).
Consider whether the leak soaked deep into the flooring. If so, will it be able to dry out?
Look For High Humidity
High humidity is a form of water intrusion.
Identify any areas with high humidity. Trapped air — in closed-off spaces — often allows humidity to rise.
If you pay attention, you can feel how humid air is.
Put a hygrometer in various places around the house. You want indoor humidity to be lower than 60%. Under 50% is even better.
Humidity above 55-60% increases the chance that mold will be growing in the area.
Look For Any Sign Of Mold Growth
It only takes a tiny drip — or high humidity — for mold to grow.
Don’t just look for visible mold — it’s often difficult to see — rather, look for signs that water is, or has been, present : bubbling, warping, smells, and other signs of mold growth.
Find and stop leaks and moisture intrusion immediately — either by yourself or with professional help.
It only takes 24 hours for mold to sprout.
You’ve explored your home and are aware any problems.
Now, take stock of your current situation — what’s going on, and how bad is it?
You likely fit into one of three scenarios:
Now, you need to stay vigilant — and prevent mold growth in your space.
Can you handle this yourself?
Mold has spread onto porous building surfaces that must be removed professionally.
You have some mold growth, but it’s contained.
A small leak — or one appliance — appears to have caused some mold growth.
Being a small problem, you may be able to handle this, yourself.
Have a plan before you start.
Consider the following:
Tread gently and carefully as you fact-find. Limit touching surfaces as you explore contaminated items. Wash your hands immediately after and shower, if necessary.
When you’re ready to clean, do so precisely and quickly — all at once.
First, Remove Exposed Items
Quickly pull out all questionable objects that were exposed to mold.
This includes plastic, wood, and cloth materials.
Mold can attach to plastic. Get rid of any plastic that’s been exposed to mold.
The only items that should be saved are expensive or meaningful items that have non-porous surfaces.
Have a trash bag handy that you can quickly tie-up and remove from the home.
Then, Clean Up The Area
Wipe mold up very carefully and slowly, so it isn’t disturbed and releases fewer spores.
Go over the area multiple times, and saturate with a disinfectant cleaner (suggestions here) extremely well. To greater reduce the odds of mold returning, wipe down the area with disinfectant every day for a week, and then weekly going forward.
Look to see if there’s a chance the mold has spread inside walls, cracks between finishes, or mechanisms. If so, the materials need to be removed.
Have a trash bag on hand to immediately put dirty and contaminated wipes in.
Be mindful of getting mold spores on your hands. Close the trash bag immediately when done, wash hands, and remove the bag from the house.
Finally, wipe down everything in the room with microfiber and a great disinfectant cleaner. Clean sheets if in a bedroom. Change clothes and shower off, then get outside for some restorative fresh air.
Be mindful that disturbing mold will release invisible spores in all directions.
The Best Disinfectant Products
Benefect Decon 30
The Best Product To Prevent More Mold
Cleaning Vinegar — add Essential Oils
Mix in a spray bottle. Vinegar doesn’t have to be diluted. Put as many drops of Tea Tree oil (or other oil) as you like — the only concern is the cost of the oil.
Other essential oils are quite antiseptic — Thieves oil, clove oil, etc.
Tea Tree Oil
You can substitute Borax (in water) for the vinegar, too — it’s highly killing and safe.
Hydrogen peroxide kills mold — but be careful not to get it in your eyes.
Bleach and other harsh chemicals may agitate mold and cause them to release more mycotoxins — while releasing noxious fumes. The water in bleach can also soak into porous materials and cause more mold to grown. Bleach is not a high-caliber option for mold.
Be Mentally Ready
Cleaning mold can be a bit disturbing to the mind.
It’s hard not to feel violated — your home or workspace needs rescuing from a potential threat to your health.
If you’re not quite ready to tackle the problem — that’s okay. Take some time, gather your thoughts, and proceed when ready.
For many folks, mold exposure causes mental or emotional instability.
If this applies to you, let yourself mentally prepare for the challenge — and be sure to get some fresh air afterward.
Follow smart steps to keep spores contained, discover the extent of the water intrusion, and remove all compromised materials.
Ozone & UV
Ozone & UV light are hostile to mold, and can be used to discourage further mold growth after moisture has been removed.
Both are best suited for prevention — and once a moldy area has been cleaned, that’s precisely what’s needed.
Ozone the area frequently over the next several weeks, and continue treatments 1-2x/month indefinitely.
Was Cleaning Enough?
Maybe you thought this was a small, manageable problem.
But after cleaning, you’re wondering if you fully eliminated the problem.
Sometimes, we think we’ve got a small problem — only to realize it’s bigger.
A Medium-Sized Problem That Probably Should Have Been Remediated
Workplaces are notorious for skimping on building health.
The problem is severe when mold has grown onto porous construction materials.
Here, you will likely need professional help.
Too Bad To Remediate?
With large problems, you’ll need to make a decision, up-front.
If the mold growth is severe enough your best bet may be moving to a new home.
This is because remediation is widely known to be unreliable and extremely costly.
Your health matters most, here. Can all mold materials and all spores be removed from the house?
Factors To Consider
- How long has this house been moldy?
- Was this contained?
- Did it spread to the whole house?
- Was there traffic through the contaminated area(s)?
- Did mold spread to the HVAC system?
- Did tests show high spore counts?
- Did tests show particularly dangerous mold species?
- How do you feel being in the house?
Trust Yourself First
(&, if needed, a Highly-Skilled Building Biologist)
The internet abounds with information about mold illness.
Do your research. The person to fix the situation might be you — if you educate yourself well.
You might be needed by your family — to learn about mold, to diagnose the problem, and to fix it. You might be needed to lead them, to guide their thinking about how serious and manageable the problem is.
Some family members may need to be talked off the ledge, while others need to hear the importance of action.
Of course, if you feel a Building Biologist would be helpful, hire one.
Will Remediation Work?
Remediation very often falls short of its goal of making a home healthy.
It’s common that remediators fail to remove all moldy materials from a house. Many companies fail to prevent the spread of mold spores around the house while work is done.
It’s also possible uou may be too sick — too sensitive to mold — to tolerate all but the best, most-thorough remediation work.
Beware Low-Ball Quotes
Conventional mold remediator employees may say: “you don’t have a very big problem.”
This conclusion is often reached after only a superficial visual examination.
You may be quoted a price you’ll be more likely to agree to pay — rather than the amount of work and price that will thoroughly remedy the problem.
Remediation & Lawsuits = Stress
As hard as it sounds, leaving a home and belongings behind is often the safest, easiest, and most productive solution available.
Leaving is also often more cost-effective.
Rather than remodel and remediate — which could be spending tens of thousands on improvements that will never be recouped upon resale of the house — you might consider selling your house “as is.”
The remarkable reality is that most buyers will not care about mold, even when explicitly told what’s happening in the home. After all, mold is extremely common.
The unfortunate result of remediation is that families spend tens of thousands in multiple failed remediations, only to finally realize they need to leave the house.
By law, mold issues must be disclosed to potential buyers. That said, many simply won’t care that there’s a problem.
If You Remediate
Remediation is common, because indoor mold is common.
Mold remediation companies do exist in most areas.
However, remediation work is no simple endeavour.
Remediation Is Risky
Sadly, there are more bad remediation stories than happy endings.
This is for several reasons: big money is involved, the variables are complex, companies are not trustworthy, and your sensitivity may leave you with exacting needs that can’t be met by most businesses.
Mold “experts” in your area usually aren’t experts in mold illness — their primary interest is to sell you on their service, not your long-term health.
Awareness, Your Superpower
Explore buildings. The more you learn about the “built environment” and how water interacts with it, the better off your family’s health will become.
If you suspect “something isn’t quite right” — you have the capability to poke around and discover the facts.
This completes Awareness.
To continue, select Clean.
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