How To Prevent Attic Mold + Attic Mold Tips

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When was the last time you ventured into your attic? Probably been a while hasn’t it? Attics typically remain empty spaces that are often forgotten about until a roof leak occurs.

Since attics are often “out of sight, out of mind” they easily become a hotbed for mold. Believe it or not, attics are one of the most common places for mold growth in a home.

This is because attics have the perfect conditions for mold growth. Moisture, heat, and humidity are attic mold’s best friends.

Let’s dive into attic mold and learn what causes it, how to prevent it, what to do if you find mold, and some other attic mold tips.

A cluttered attic illustrating what not to do to prevent mold

What Causes Attic Mold?

Mold grows in attics due to four main reasons.

  1. Warmer temperatures
  2. High humidity, condensation, or major water intrusion from a roof leak
  3. Improper ventilation, no ventilation, or blocked vents
  4. Lots of food (insulation, wood, dust, stored household items)

Signs You Have Mold In The Attic

In no particular order, here are 8 common signs of attic mold.

  1. Water stains on your ceiling. This could be from a new or old leak but any water staining should be investigated.
  2. Water dripping from smoke detectors, light fixtures, bathroom exhaust fans, and ceiling fans. This is a sure sign that the attic has a level of moisture that needs to be addressed. Mold growth is highly likely.
  3. GFI outlets tripping regularly for no apparent reason. If your plumbing is in the attic and begins to leak or you have a roof leak, often times it will come through the attic, down the wall, and begin to trip the GFI outlets.
  4. Wet insulation in the attic. Attic mold loves wet insulation. In fact, it often times take only 12 hours for certain types of insulation to start growing mold. This is why mold resistant insulation is so important in an attic.
  5. Dark black staining on wood surfaces in the attic. A lot of remediation companies write off darkened wood on beams in the attic as “aging.” Sure, wood can change color a bit as it ages but aging wood in the attic doesn’t develop dark patches here and there. If you see dark brown or black areas on the wood, chances are you have mold in the attic.  
  6. Attic feels very hot or stuffy. When attics are properly ventilated, they should have the feel of a gentle (but warmish) breeze. When an attic is stuffy, that indicates you have a ventilation problem, which often results in mold problems.
  7. A musty smell in the attic. Sure, mold can smell like a lot of things but an attic with mold will always have a pretty musty type odor.
  8. Frost buildup on the underside of the roof sheathing in winter. When it’s cold enough outside, water vapor in an attic with improper ventilation can freeze on the underside of your roof. While this is easy to spot, by the time you see it mold may have already begun to grow.
Attic mold and mold in an attic

Is Attic Mold Dangerous?

Yes. In fact, attic mold can be more dangerous that other molds because it goes unnoticed for so long. This allows it to penetrate into walls, the HVAC system, ductwork, and more. By the time most people realize they have a mold problem in the attic, their entire house is compromised with high levels of air born mold.

How Do You Prevent Attic Mold?

Inspect your attic four times per year. This is the best way to ensure that a leak doesn’t go unnoticed for too long and that everything else is copacetic in attic land. Things to look for include:

  • Discoloration of insulation and wood (e.g. rafters, sheathing, joists, attic side of fascia boards, etc.).
  • Wet areas in roof valleys (where two roofs join at an angle), which are highly susceptible to roof leaks.
  • Raised shingles. When shingles become brittle and dry they are subject to nails pushing the shingles upward and exposing the interior joists and other structures of the interior roof. High winds can also push old and damaged shingles upward allowing rain into your attic.
  • Skylights, chimneys, attic windows and any portion of the attic/roof where dissimilar materials join each other (including flashings). These places are hotbeds for potential moisture intrusion.
  • Condensation underneath a vapor barrier if one is installed.
  • Leaks coming from and around attic plumbing stacks.
  • Soffit vents.  Make sure they are free of insulation, bird nests, and other debris that could be blocking them and preventing proper air flow.
  • Discolored insulation. This is a sign of leaking air as insulation acts as a filter, becoming discolored in areas of air infiltration.  Leaking areas can typically be caulked from within the attic to prevent warm, moist interior air from entering the (cold) attic where it may condense and create elevated moisture conditions conducive to mold growth.

Spray your attic with Endurance BioBarrier. This is the holy grail of mold prevention in places like attics and crawl spaces. When conditions promote mold growth in the attic, a polymer film “opens”, exposing the active ingredients to kill off fungus and bacteria. As moisture decreases, the surface film then reseals, locking the mold eliminating ingredients back in. Endurance BioBarrier is guaranteed to prevent mold for up to 25 years in spaces like the attic. You can learn more about Endurance BioBarrier here.

Dryer exhaust vents, kitchen exhaust fans and bathroom exhaust fans are designed to pump moisture out of your home. Make sure that they are vented to the outside of your home and not in the attic. Also plumbing stacks in the attic can be a source of condensation, which can lead to attic mold growth. Each appliance and vent should have it’s own dedicated port to transport the hot air outside. However, because dryer vents require periodic cleaning, you’ll want to easily access the inside of the pipe to remove any lint build up, therefore, your dryer vent should have a removable section of pipe in the attic area.

Don’t over-insulate. Sound weird but attics are weird. Adding too much insulation will make mold growth more likely. Why? Your roof needs a certain amount of heat to reach it so it can dry out moisture in the air. Over insulated cold attic + wet winter air = mold growth.

Make sure insulation is properly installed. Insulation should prevent warmer air from penetrating into the colder attic, which will cause condensation and moisture build up. But like I mentioned above, don’t over insulate either. Check that there is insulation:

  • On and surrounding your access panel (the pull-down stairs or utility hole you use to enter the attic)
  • Surrounding your skylight chases
  • On the attic floor or if you have finished attic floors, between your attic floor and living quarter’s ceiling.
  • In any empty wall spaces between the attic and other parts of the house (crawl space, open chases, etc.)
  • Heating ducts – insulate their surface to help your heating and air conditioning system perform more efficiently. Besides wasting expensive energy, heat released from the air ducts surface might condensate on the roof decking surface and cause mold growth.

Furnaces and water heaters installed in attic areas should be contained inside a separate and insulated room – code requirement in some jurisdictions. Have both these items inspected twice a year and serviced if there is an issue.

Install an attic vent fan.  This is extra insurance against potential future elevated moisture conditions because the fan will turn on when/if elevated moisture conditions present. This is a popular solar powered attic fan.

Do not install a vapor barrier on top of insulation. Moisture in the attic cannot pass through the insulation and out the vents. Instead it gets trapped by the vapor barrier allowing mold to grow in the insulation.

Use externally baffled ridge venting. Externally baffled ventilation relies on barriers on the outside to prevent water intrusion.  This allows for much larger openings in the actual ventilation portion of the ridge vent.  These ridge vents also sit significantly taller than a typical internally baffled model.  This also allows for great air flow. If you have a choice, choose externally baffled ridge venting over the internally baffled model.

Prevent ice dams. Ice Dams occur when water can’t drain properly from the roof, freezes, and backs up into the home through the attic. The stagnant water causes attic mold growth. Clean your gutters regularly. As you’re cleaning the gutters, look for leaks and misaligned pipes and make sure the downspouts carry water at least 10 feet away from the house’s foundation.

Don’t used your attic as storage. The less there is in your attic, the better.

An attic being used as storage which promotes mold growth

Help! I Have Mold In My Attic? How Do I Remove Attic Mold?

YOU don’t. Attics are dangerous and structurally difficult to deal with. You are working in a small space with very little ventilation which makes breathing quite difficult when you are wearing a respirator.

I had a pipe burst in my attic and it resulted in a small mold issue. However, there was a lot of attic that had to be removed and repaired. This is NOT a DIY job. Professional mold remediation is prudent when it comes to attic mold.

One piece of advice I will give you is to remove as much of the attic insulation as possible. Mold spores root deep in the stuff and spread everywhere. The more insulation you can remove and replace, the better.

But What If I Have Just A Small Amount Of Attic Mold?

You certainly can do what you want but remember – insulation is the perfect vehicle to hide and spread mold spores. Mold growth on wood = mold spores in your insulation.

If you do want to try a DIY approach to removing attic mold, please do so carefully and safely. You will need to properly contain the area so when you remove the moldy material you don’t send more spores flying.

As you can see, attic mold is not only difficult to deal with once you have it but it also requires a lot of special preventative measures. However, it is 100% worth the effort as attic mold can have devastating consequences both on a building structure as well as the inhabitants health.

Mold in an attic

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  1. Rick Davis says:

    It’s good to learn that a fan in your attic can help protect mold from growing in it. My wife and I are renovating our house and we were wondering what we could add to it to help protect against possible mold growth. I’ll be sure to talk to my wife about possibly getting an attic fan to protect against mold.

  2. Loft and Insulation says:

    Thanks for posting. Keep on sharing your brilliant ideas.

  3. Tacoma Mold Removal Co. says:

    Thank you for this valuable information! If mold is a problem in your home, you should clean up the mold promptly and fix the problem. If you are unsure about how to clean it consult a professional.

  4. Tulsa Mold Removal says:

    Thank you for this valuable information! Attic mold is very common and very dangerous to try to fix on your own. So it’s best to call trusted attic mold removal experts for your peace of mind and for your family.