Does Mold Die When It Dries Out? And Is It Dangerous?

Mold is an unpleasant sight as it is, but many homeowners aren’t sure what to make of dry mold in particular. Are the mold spores still active now that the mold has dried out or has the mold died?

Mold does not die when it dries out but waits inactively for moisture to return. If any moisture does come back, the mold can continue to propagate. If it doesn’t, then the mold will remain inactive but still alive.

This guide will seek to answer all your most pertinent questions about dry mold, such as whether it’s dangerous and if you need to remove it. Make sure you keep reading!

Does mold die when it dries out

Will Mold Dry Up and Die?

Mold grows best in a moist, damp environment. Once you take those optimal conditions away, it reasons to assume that the mold would die.

That would make its removal convenient for homeowners, as you’d only have to dry out the mold and then scrape it away.

That’s simply not how it works, though. In the absence of moistness and dampness, mold will dry out, but it’s not dead.

The mold is inactive, as we touched on in the intro. You can think of the mold as being in a period of hibernation.

In those roughly eight months a bear hibernates, it’s still alive but will not awaken and get up.

It’s the same case for mold, but its span of hibernation can last a lot longer than eight months. We’ll talk later about the timeframe, which you won’t want to miss.

Can Mold Grow If It’s Dry?

Mold may be alive whether it’s moist or dry, but there is a difference between the two that goes beyond the feel of the mold.

Mold in humid, moist conditions can easily propagate. Dry mold cannot.

You’ll recall that the mold is inactive almost like it’s sleeping.

In this state, the mold cannot spread.

Thus, a small patch of dry mold on your attic ceiling will stay the same size from day to day and possibly even week to week.

If at any time the conditions become moister, the dry mold will be reinvigorated and begin regrowing.

The best time to remediate dry mold is right away before the problem becomes more severe.

Do Mold Spores Die Without Moisture?

If a lack of moisture prevents mold from growing, then surely starving the mold of moisture for long enough would kill it.

Well, not exactly. In the next section, we’ll go over the timeframe for mold survival without moisture, in which case this section will make more sense.

For now, we cannot stress enough the point that mold is only inactive when it lacks moisture. It’s not dead.

Starving the spores of moisture merely prolongs the inevitable growth that will begin anew when conditions change. If you want to ensure the mold is dead for good, you need to fully remove the spores from your home.

How Long Can Mold Spores Live Without Moisture?

So, how long mold spores can live without moisture?

The answer is practically indefinitely.

Some sources estimate that mold can survive for upwards of hundreds of years without a drop of moisture. The mold is sure to outlive any family currently in the house with a mold problem.

This is why we said in the last section that starving the mold of moisture only prevents the inevitable.

At What Humidity Does Mold Die?

As discussed, most molds will not die when moisture levels drop, they simply hibernate. However, you can reduce their spread and growth by decreasing the moisture levels in your property.

You’ll want to reduce the humidity in your home to between 35 and 50 percent. The level of humidity where mold can being to grow and spread is around 55 percent, therefore keeping your home under this level of humidity puts you in the best position to mitigate its ability to spread.

Then you can use a mold-removing product such as hydrogen peroxide, white vinegar, or even tea tree oil if you’re looking for a more natural remedy.

Are Dry Mold Spores Still Dangerous to Humans?

Keeping in mind that inactive mold spores are still alive, dry or not, the spores are indeed dangerous to human health.

Mold allergy sufferers can come down with symptoms such as sneezing, coughing, itchy eyes, runny nose, and skin rashes whether the mold they’re exposed to is dry or moist.

The mold spores may not spread with such fervency since the mold is dry, but the air is still not clear. That can leave an asthma sufferer contending with wheezing, a tight feeling in the chest, coughing, and shortness of breath.

Even those with healthy lungs are not immune to the health havoc that mold can wreak. Again, the spread of the spores is not as far as if the mold was moist and propagating, but even a little mold in the house is still dangerous.

After all, Healthline lists the short-term side effects of mold exposure as:

  • Headache
  • Hives, rash, or other skin irritation
  • Nosebleeds
  • Sneezing
  • Sore throat
  • Coughing
  • Breathing difficulties
  • Wheezing
  • Blurry vision
  • Red, itchy, and watery eyes
  • Congestion

None of these symptoms are particularly severe, but for an allergy or asthma sufferer, they would be.

Repeated mold exposure also worsens symptom severity, even among those with healthy lungs.

Healthline notes the symptoms may now include organ damage, fatigue, chronic sinusitis, and lower and upper respiratory symptoms.

Your risk of being diagnosed with a mold allergy and Legionnaire’s disease also goes up considerably.

Should You Remove Dry Mold?

For the benefit of your health and that of your family, it’s worth removing dry mold.

To reiterate our point from earlier, removing mold while it’s dry is a prime time to act. The mold cannot actively spread, so you only have to contend with as much mold as you can see.

If the mold removal process takes longer than an afternoon and you have to return to it the next day, you can rest mostly assured that the mold won’t spread.

We say mostly because that all depends on the conditions.

For example, if your attic was very moldy because it’s uninsulated and you had a hot summer, then in the autumn and through the winter, the mold might have dried.

All it takes is one unseasonably warm day and the moisture levels are high enough that the mold is back to growing again.

Does Dry Mold Smell?

Mold isn’t always easy to visually detect, especially if it’s growing under floorboards or behind the wall.

In situations like those, you might rely on your sense of smell above all else to discern mold.

What about dry mold? Does it have a noticeable smell? Yes, it does, but the smell is not necessarily all that different from how regular mold smells.

The odor can be musty and earthy. The scent is sometimes likened to dirty gym socks and can leave the air feeling stale.


Dry mold might not have active spores that can spread, but it’s still mold at the end of the day and thus should be removed. Considering that dry mold can affect your health and that of your family as well, don’t ignore dry mold if you see it!

Chris Walker

Chris Walker has struggled for several years with mold after buying his own property. After finding the solutions to several issues around his home, he decided to create this site in order to answer as many questions about mold and mildew as possible to help others dealing with the same problems.

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