Recently, someone reached out to me after searching online for a “mold-free Realtor in Colorado.”

That phrase caught my attention because, technically, there really isn't such a thing as a completely mold-free home. Mold spores exist naturally in our environment and make their way indoors all the time. The important distinction is whether conditions inside a home are allowing mold to actively grow.

But the interaction got me thinking.

I've written before about environmental factors I want buyers to consider when choosing a home. I've written about carbon monoxide and how to protect your family from something you can't see or smell. And I've realized there's a common thread here that matters deeply to me:

Of all the places in this world where we should feel safe, our homes should be IT!

It's where we sleep at night. It's where we raise our kids. It's where we cook dinner, celebrate birthdays and holidays, recover when we're sick, invite the people we love and spend an enormous portion of our lives.

It's also, for most of us, the largest financial investment we'll ever make.

I'm not a mold inspector, environmental hygienist, remediation contractor or physician. I'm a Realtor. But I believe part of representing someone well is knowing what questions to ask, recognizing when something deserves a closer look and knowing when it's time to bring in someone with expertise beyond mine.

So consider this a starting point—not a substitute for an inspection, professional environmental assessment, medical advice or your own research.

Because when it comes to mold, there's a lot more nuance than “black mold = run.”

First Things First: Mold Is Really a Moisture Story

If you remember only one thing from this entire article, make it this:

Mold is usually a moisture problem before it's a mold problem.

Mold spores exist naturally both outdoors and indoors. It's essentially impossible to eliminate every mold spore from a home.

But mold needs moisture to grow.

That moisture can come from an obvious source—a leaking roof, burst pipe or flooded basement—or something much less dramatic: condensation, a slow plumbing leak, an improperly ventilated bathroom, water intrusion around a window or chronically elevated humidity.

That's why simply removing visible mold isn't enough.

You have to figure out why it grew there in the first place.

If the moisture source remains, there's a good chance the mold will eventually return.

Another number worth remembering is 24–48 hours.

When building materials get wet, the EPA recommends drying them within approximately 24–48 hours whenever possible to help prevent mold growth.

And unfortunately, I learned that one firsthand.

I've Actually Had Two Very Different Mold Experiences in My Own Homes

Years ago, my husband and I were remodeling the primary bathroom in our townhome. When we removed some trim around the bathroom door, we discovered a tiny fuzzy patch of dark-colored mold on the wood underneath.

When I say tiny, I mean smaller than a quarter.

Naturally, my first reaction was:

BLACK MOLD. WE HAVE BLACK MOLD. DO WE NEED TO REMEDIATE THE ENTIRE HOUSE?!

Our contractor told us no. It was an extremely small, localized area, and he didn't believe professional remediation was warranted.

At the time, I simply trusted his judgment.

Knowing what I know now, there's an important lesson in that experience: you cannot identify a mold species—or determine how concerning it may be—simply because it's black, green, white, fuzzy or any other particular appearance.

And a quarter-sized spot is very different in scope from extensive mold growth or widespread water damage.

Fast-forward several years to a completely different house and a completely different situation.

Colorado had one of those bizarre stretches of weather where it rained every single day for weeks (summer 2024 - IYKYK). Everything outside was gloriously green.

My roof was considerably less enthusiastic about it.

A leak developed above my office and completely saturated one corner of the room. It took a couple of days to get someone out to investigate, and by then the water had soaked through the building materials. The insulation was saturated, the drywall was wet and we could actually see mold beginning to grow on the drywall.

That was not a quarter-sized spot behind a piece of trim.

We brought in a professional remediation company. The room was contained, equipment was brought in, affected materials were addressed and my office was essentially off-limits for an extended period while everything was remediated and dried.

Those two experiences are why I don't think the useful question is simply:

“Is there mold?”

The better questions are:

How much? Why is it there? What got wet? Is the moisture source resolved? What materials are affected? And who is the appropriate professional to evaluate what happens next?

Why Colorado Homes Aren't Immune Just Because We Live in a Dry Climate

Living in Colorado can give us a bit of a false sense of security when it comes to mold.

We're dry! We don't have Florida humidity! Surely this isn't our problem.

Not exactly.

Yes, Colorado generally has lower outdoor humidity than many parts of the country. But mold doesn't require a tropical climate.

It requires moisture in the wrong place for long enough.

And Colorado homes have plenty of opportunities to get wet.

Think about:

• Roof leaks from heavy rain, snow, hail damage or aging roofing materials
• Snow and ice followed by melting
• Poor drainage around foundations
• Water entering basements or window wells
• Plumbing leaks
• Failed appliance supply lines
• Leaking showers or tubs
• Condensation around windows or other surfaces
• Crawlspace moisture
• Improperly vented bathrooms
• Whole-home humidifiers that aren't operating properly
• The occasional Colorado summer when apparently Mother Nature forgets we live in a semi-arid climate and it rains for two months straight

In other words, the outdoor air may be dry, but one leaking pipe behind a wall can create its own little climate.

And newer doesn't necessarily mean immune, either.

This is something I've had home inspectors point out over the years, and the building science behind it is interesting.

Today's homes are generally built much tighter and more energy-efficiently than older, draftier houses.

That's largely a very good thing.

A well-designed tight home can be more comfortable, more energy-efficient and give us much better control over the air we're breathing.

But it also means we shouldn't depend on random cracks and drafts to exchange indoor and outdoor air. Modern homes increasingly rely on intentional ventilation and good moisture management.

So if moisture is introduced—from a plumbing leak, condensation, a shower that isn't venting properly or another source—it still needs to be addressed and the affected materials need an opportunity to dry.

That doesn't mean newer homes are inherently more likely to have mold.

It means ventilation matters.

Bathroom and kitchen exhaust fans, properly designed HVAC systems, whole-home ventilation where applicable and good moisture control all become part of keeping a tight modern home healthy.

It's also one more useful question to ask when you're buying newer construction:

How is this home designed to exchange fresh air and manage indoor moisture?

A home's moisture history, drainage, roof condition, ventilation, plumbing and maintenance ultimately matter far more than whether the house is old or new—or whether our Colorado air feels dry.

Buying a Home? Start Looking for Moisture Before You Look for Mold

When I'm showing a house, I don't expect my buyers to crawl through an attic, pull up carpet or start dismantling somebody else's bathroom.

In fact, please don't do that. The sellers would get real mad!

That's what the inspection period—and trained professionals—are for.

But you absolutely can, and should, use your eyes, your nose, and some common sense during a showing.

Sometimes what you notice is enough to tell us we need to investigate further.

What I Want Buyers to Notice During a Showing

Use your nose.

A persistent musty, earthy or damp smell deserves attention, particularly in:

• Basements
• Bathrooms
• Laundry rooms
• Closets
• Lower-level bedrooms
• Rooms below bathrooms
• Areas near crawlspaces

A smell doesn't diagnose a mold problem. But it can give us a reason to ask more questions.

And if the house smells overwhelmingly like air freshener?

I'm not saying something nefarious is happening.

I'm just saying my nose is going to be curious about what we're not smelling.

Look up.

Ceilings can tell stories.

Watch for:

• Brown or yellow water stains
• Bubbling or peeling paint
• Sagging drywall
• Areas that appear recently patched
• A strangely fresh patch of paint on an otherwise older ceiling

A water stain doesn't necessarily mean there's an active leak. It could be evidence of an old leak that was properly repaired.

But we're going to ask.

Look around windows and exterior doors.

Pay attention to:

• Water staining
• Swollen trim
• Peeling paint
• Condensation
• Soft or deteriorated wood
• Visible growth around frames

Windows are one of the places where water intrusion and condensation can leave clues.

Open the cabinets under sinks.

This takes approximately five seconds and can tell you quite a bit.

Look for staining, warped cabinetry, deteriorated materials, active dripping or that unmistakable damp smell.

Do the same around toilets, tubs, showers, refrigerators with water lines, dishwashers and washing machines when they're accessible.

Pay attention downstairs.

Basements and crawlspaces deserve special attention because moisture can enter through foundations, drainage problems, plumbing failures and groundwater.

Look for:

• Water staining
• Evidence of past moisture on foundation walls
• Musty odors
• Damp carpet
• Warped baseboards
• Signs of previous flooding
• A dehumidifier that's working overtime
• Evidence of water intrusion near window wells

None of those things automatically means “don't buy this house.”

They mean:

“Let's understand what's happening before you buy this house.”

And there's an important flip side:

A house can look perfectly clean and still have a moisture problem.

Mold can grow behind drywall, underneath flooring, behind cabinets, inside wall cavities and in other places we can't see during a showing.

That's precisely why a showing is not an inspection.

We're Under Contract. Now What?

Once you're under contract on a home in Colorado, the inspection period gives us the opportunity to look much more closely at what you're buying.

A standard home inspection isn't necessarily the same thing as a specialized mold assessment, so if mold or moisture is a concern for you, ask questions before choosing your inspector.

Here are some I would ask:

Questions to Ask Your Inspector About Mold and Moisture

Do you routinely look for evidence of moisture intrusion and mold during your inspections?

What training or certifications do you have specifically related to mold and moisture?

Do you use moisture meters or infrared imaging when appropriate?

Will you inspect the attic and crawlspace if they're safely accessible?

Will you look for evidence of both current and previous water intrusion?

Are there areas of this particular home that you consider especially vulnerable to moisture?

If you see something suspicious, are you qualified to evaluate it or would you recommend a specialist?

Do you offer mold sampling?

If so, what kind?

Who analyzes the samples?

If you perform air sampling, do you collect an outdoor comparison sample?

How many indoor samples would you recommend for this particular house, and why?

How will you help me interpret the laboratory report?

What findings would cause you to recommend an independent mold assessor or remediation professional?

One other thing worth knowing: the EPA itself does not certify mold inspectors or mold remediation companies. Credentials, training, experience, references and the scope of someone's expertise matter.

And in Colorado, the Colorado Department of Public Health and Environment does not regulate mold as an indoor-air contaminant.

Translation?

Do your homework on the person you're hiring.

So What Exactly Is a “Mold Test”?

This is another area where there's a surprising amount of confusion.

There isn't one universal mold test.

Depending on the circumstances, a professional might use:

Air sampling

This is the method my clients encounter most frequently.

A measured amount of air is collected and sent to a laboratory, which identifies and counts fungal spores captured in the sample.

An outdoor sample may also be collected for comparison.

Why?

Because here's something that surprises a lot of people:

Finding mold spores in an air sample does not automatically mean the house has a mold problem.

There are mold spores outside.

There are mold spores inside.

There are mold spores in strawberries - I was surprised too!

There is no EPA-established federal number of airborne mold spores that universally means:

BELOW THIS NUMBER = SAFE.

ABOVE THIS NUMBER = UNSAFE.

Instead, results need to be interpreted in context—including the types and concentrations of spores found, outdoor conditions, observations within the house and whether the overall picture suggests an indoor source.

Air sampling is also a snapshot of conditions at a particular time. It isn't a magical all-clear certificate for every square inch of a building.

Surface sampling

A professional can collect a sample directly from a suspicious surface, often using tape or a swab, and send it to a laboratory for analysis.

Bulk sampling

Sometimes a piece of affected building material itself is collected and analyzed.

Different circumstances call for different approaches, which is another reason I prefer:

“What are we trying to learn?”

over:

“Can we just test the house for mold?”

And sometimes testing isn't necessary at all.

If there's clearly visible mold and an obvious moisture problem, we already know something needs to be addressed. Spending money proving that the visible mold is, in fact, mold may not be the most useful next step.

Let's Talk About “Toxic Black Mold”

Few phrases in homeownership inspire panic quite like:

BLACK MOLD.

But here's where we need to separate color from science.

Molds can be black, green, white, brown, orange and other colors. You cannot reliably identify the species—or its potential health effects—just by looking at its color.

Stachybotrys chartarum is the species commonly associated with the phrase “black mold.” It can grow on certain damp, cellulose-containing building materials.

But discovering something dark-colored on your bathroom trim doesn't automatically mean you've discovered Stachybotrys.

More importantly, if you've discovered mold growing inside your house, the practical questions remain the same:

Where is the moisture coming from?

How extensive is the growth?

What materials are affected?

How should it safely be removed?

And how do we keep it from coming back?

The EPA offers a useful rule of thumb: if a moldy area is smaller than approximately 10 square feet—or roughly a 3-by-3-foot area—homeowners can often handle cleanup themselves.

That is a guideline, not permission to ignore context.

Significant water damage, contaminated water, HVAC involvement, recurring mold, inaccessible areas, medically vulnerable occupants or other complications are good reasons to seek professional guidance regardless of square footage.

Can Mold Make You Sick?

It can affect people's health, but this is an area where I think it's especially important not to overstate what we know.

People do not all react to mold exposure in the same way.

Mold exposure can cause allergic reactions and irritation. People may experience symptoms such as sneezing, runny nose, red or irritated eyes and skin irritation. Mold can also trigger asthma attacks in people with asthma who are sensitive to mold, and exposure can irritate the eyes, skin, nose, throat and lungs.

Certain people may be more susceptible than others.

And this is where my professional lane ends.

I've worked with clients for whom mold exposure and indoor environmental quality are significant concerns. If you believe your home may be affecting your health, that's something to discuss with an appropriate medical professional alongside qualified professionals who can evaluate the building.

Your Realtor should take your concerns seriously.

Your Realtor should not diagnose you.

What If You're Not Buying a House at All?

This may actually be the most important part of this article.

Because my two experiences with mold didn't happen while I was buying either home.

They happened while I was living in them.

A house that was dry when you purchased it can develop a roof leak five years later.

A dishwasher line can fail.

A shower can start leaking behind a wall.

A window can begin allowing water intrusion.

A basement can take on water after an unusually wet season.

A tiny plumbing leak can go unnoticed beneath a sink.

Owning a healthy home isn't something you accomplish at closing and never think about again.

So here's what I want homeowners to know.

How to Make Your Home Less Hospitable to Mold

Deal with water quickly.

If something leaks, floods or becomes saturated, don't put it on next week's list.

The EPA recommends drying wet materials within approximately 24–48 hours whenever possible.

My office experience is a pretty good illustration of why.

Control humidity.

The EPA recommends keeping indoor relative humidity below 60 percent and ideally somewhere around 30–50 percent.

A small hygrometer is inexpensive and can tell you what's actually happening inside your home rather than relying on how the air feels.

Actually use the bathroom fan.

Yes, I'm talking to everyone who turns it off the second they step out of the shower.

Moisture generated by showers needs somewhere to go. Make sure bathroom exhaust fans are functioning properly and, ideally, venting to the exterior rather than dumping humid air into an attic.

Don't ignore condensation.

If you're regularly seeing moisture collect on windows, pipes or walls, figure out why.

Condensation can be a clue that humidity or ventilation needs attention.

Look underneath things occasionally.

Every so often, open the cabinet beneath the sink.

Look behind the washing machine.

Check around the water heater.

Look at the ceiling below an upstairs bathroom.

Check the basement after an unusually heavy rain or rapid snowmelt.

You don't have to become obsessive about your house.

You just have to notice when it starts telling you something.

Maintain the exterior too.

Roofing, flashing, gutters, downspouts, grading and drainage all play a role in keeping water where it belongs:

outside your house.

And please don't just paint over a water stain.

Find out where the water came from first.

Pretty paint does not fix physics.

When Do I Call a Professional?

There's no perfect universal formula, but I would be much quicker to seek professional guidance when you're dealing with:

• Extensive visible mold
• Significant water damage
• Repeated mold growth after cleaning
• An unknown or unresolved moisture source
• Suspected mold inside walls, ceilings or other inaccessible areas
• Saturated porous building materials
• HVAC contamination
• Floodwater or sewage
• A persistent musty odor with no visible explanation
• Occupants with significant mold sensitivities, respiratory conditions or other medical concerns

My roof leak checked several of those boxes.

My quarter-sized bathroom surprise did not.

And that's an important distinction.

The Goal Isn't a “Mold-Free” House

Which brings me back to the phrase that prompted this article in the first place:

“Mold-free Realtor.”

I wouldn't describe myself that way, because I can't promise anyone a mold-free house—and I wouldn't trust anyone who did.

What I can do is help my clients become better observers and better question-askers.

I can notice the water stain.

I can ask what happened.

I can encourage you not to dismiss the musty basement.

I can help you find qualified professionals when something deserves further investigation.

I can make sure that if indoor environmental quality is particularly important to you, I understand that before we start looking at homes.

And perhaps most importantly, I can remind you that gorgeous countertops or a wine cellar don't tell us what's happening behind the drywall.

A home can have the perfect kitchen, the perfect backyard and the perfect neighborhood.

But none of that matters very much if you don't feel comfortable letting your family sleep there at night.

Of all the places in the world where we deserve to feel safe, our homes should be one of them.

And while I'm certainly not the expert on everything that can affect the health of a home, I care deeply about knowing enough to ask the right questions—and knowing when it's time to bring in someone who knows more than I do.

That's the kind of Realtor I want to be.

A Note About This Guide

This article is intended as general educational information and a starting point for your own research. Mold and moisture issues vary significantly from home to home, and individual health concerns vary from person to person. Nothing here should be considered a substitute for advice from a qualified home inspector, mold or indoor-environmental professional, remediation contractor, physician or other appropriate specialist.

If you're buying or selling a home in Colorado and indoor environmental quality is important to you, let me know. It's a conversation I'd much rather have before we walk into the first house.