Do I Have Mold in My Attic?

Jun 23, 2023

I often get asked, “Do I have mold in my attic?” The answer: Yes, everyone has some level of it in their attic! This is normal. In fact, I’ve seen it in virtually every attic I have inspected in the past decade since I became president of Chicago Green Insulation.  But unless you have unexplained medical conditions like migraine or nose bleeds it is very unlikely you have a health issue due to the mold.

So, let’s talk about the steps to follow if you find that you do have unhealthy mold or worry that you have a mold issue – or worse you had mold, you paid someone to “fix” it, and you have the same issues again.

If you have a mold issue, you really have a moisture issue.  For mold to propagate and create issues with the structural integrity of the roof or shorten the life of your shingles, you are not properly venting the attic and removing the moisture from inside of your home.  Some of the causes of moisture in your home include: showers, cooking, humidifiers, and more.

The first step is to understand the humidity levels in your home and in your attic. They should not exceed 30 to 40% in the winter and not be above 50% in the summer.  To gauge the levels, get two or more old school humidity sensors. (Yes, fancy thermostats are pretty and fun when they connect with your devices, but they are not always accurate when measuring humidity.)


So, what could be leading to the excess humidity?

In the winter, it is typically a problem when you have your whole house humidifier running too much. Simply turn it off to see if your home drops to the normal range.

Then, if so, just have your HVAC company service the equipment and you’ve solved the “source” of the issue and things should eventually dry out, although you might need remediation if it has been happening for a long time and/or the damage is severe.

If you are having humidity issues in the summer, it is often your air conditioner’s lack of proper dehumidification. To solve it, set the fan to circulate the air all the time which should equalize the humidity around your home.

Again, you must confirm that all sources of moisture in the home are properly being vented to the outside, through the roof, with good quality fans.


What about roof vents? 

Do I need more or a different type of vent? This is a tricky question, but here is the formula: One square foot of ventilation is required for every 300 square feet of enclosed attic space, with half of it being exhaust and half being intake (this is the most common failure in roof ventilation). In other words, for a home with 1500 square feet of attic floor space, you’ll need five square feet of attic ventilation. If you do not follow this rule regarding intake and exhaust, you can cause the moisture in your attic to be trapped and not vented properly.

(If you need to talk to a roofer to correct this situation, call us and we can share the names and numbers of qualified contractors in your area – or look on Jackie’s List for Jackie Mack & More’s trusted vendor list.)

The number one issue leading to moisture issues in attics is improperly vented bath fans where the vents terminate in that attic flooding the attic with humidity. Good news is there is a simple fix: simply extend the duct to a “roof jack” and allow the moisture to pass through the attic and out of the home.

If moisture issues are occurring in the winter, it’s very likely that you also have an issue with the whole-house humidifier or the steam shower. To determine if it is the whole-house humidifier, simply turn it off and see if the issue goes away.

If it is the whole-house humidifier, contact your HVAC service provider for servicing or ask us or ask the team at Jackie Mack & More for a referral to an organization that can properly maintain your whole-house humidifier.


Other issues causing moisture

Additional issues that can lead to the attic being too humid is the lack of an air seal at the floor of the attic. Can lights can also be a source of excess humidity in the attic.  If you have can lights, we strongly suggest swapping out the existing bulbs for Air Sealed, LED Retrofit lights, which can help reduce humidity moving from the home into the attic.

If there are isolated areas in your home where moisture is condensing in the winter, it could be caused by a lack of air circulation. To fix it, ensure you have good air movement by keeping your HVAC system fan on, and then use ceiling fans in the areas with condensation issues to further circulate air.

If you see small areas of condensation on windows, open the window coverings, when possible, to allow for air circulation. Since windows are the coldest surface in your home, these areas will be the first places most people see condensation. Use it as a warning sign to seek to lower the overall humidity levels in your home.


Mold for the first, second, or third time.

Now let’s talk about what to do with the “problem” once you have isolated the source and then let’s talk about what to do if mold is coming back for a second or third time.

In any newly found case of mold in the attic, the first key question is: “Do you have an ongoing problem that needs a solution or is the mold something that will go away on its own now that we have stopped providing moisture into it?” After all, a few black spots, or issues with the far corner of your attic that the home inspector identified during the home inspection are unlikely to need much after we have diverted the source of the moisture.

For mold that is larger than a few black spots, you will need to make good choices about who would be the right person to determine how the cleanup should go. The person you should be talking with is a licensed hygienist, someone who’ll determine what is going on and what needs to be done and will provide you with a certificate that all mold has been successfully removed, per testing at the end of the process.

Please note that there are many options for mold treatment that will not provide you with the path to a mold-free future in your home, so be very cautious about whom you trust. Look for the license as well as a signed certificate at the end that certifies your home is now “mold free.”

For those of you who have been through this more than once, the mold is returning either due to moisture still being introduced into the attic space and/or the original mold was not properly removed.

A foam solution

For those of you dealing with mold in the attic, spray foam insulation is a fantastic solution after the existing problem has been successfully resolved.

When we are looking at potential jobs, we strongly suggest that you have the proper ventilation of moisture and by foaming the attic, you do not need to modify the ventilation in the attic. And for homes without easy ways to vent the attic, foam may be the only workable solution. Pardon the pun, but “comfort is only a Foam Call away!”

Give us a call if you’d like to discuss. After all, we aren’t here to sell you a product. Rather, we’re here to use our expertise and years of experience in construction and design to find the solution right for you and your home.

By: Tom Decker, Owner & Founder of Chicago Green Insulation, can be reached at (847) 987-3626.

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