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Is Mold In An Attic A Big Deal?

Mold in a residential attic

The answer is that it all depends.  Let me try to explain.  Mold needs moisture in order to grow.  No moisture; no mold.  In attics, moisture can occur from a leak in the roof or from condensation due to elevated levels of humidity (typically from improper ducting from a bathroom exhaust fan).  Mold has the possibility of growing on attic sheathing, which is typically a wood product (something mold likes to eat).  A surface sample can help determine if these stains are mold growth.  

Many times, even if a surface sample does show mold growth, it may not be an indication that it is resulting in excessive levels of mold spores in the living spaces below.  Why is that?  It’s something called “stack effect”.  This means that warm air is more buoyant and rises. Air generally moves from the lower levels of a house up through the top.  If mold growth originates in the attic, it is hard for spores to fight against this pressurization.  Attics can also (although not always) have a higher level of ventilation which can help remove the spores.    

Does that mean that it’s not a big deal to find mold growing in an attic?  Healthwise, issues can still occur if an occupant has a hypersensitivity and there is an HVAC system or ductwork in the attic space.  Mold spores can be sucked up into the return ductwork and spread throughout the home.  Even if the spores are more or less contained in the attic, the very presence of mold indicates a moisture issue which can lead to rot and destroy sections of the roof.  Although not a huge health issue, removing rotting wood can be a very expensive project.

We have seen attic mold discovered during a real estate transaction kill the deal.  Therefore we recommend people remediate attic mold if for no other reason than to avoid concerns from a nervous purchaser in the future.

So to answer the question about how big a deal it is to have mold in the attic, one needs to contemplate how moisture is entering into this space and how much damage is occurring because of it.  Occupants also need to ascertain if there is any possible way that the spores can access the living areas of the house from the attic.  Although attic mold is typically not a huge health issue, it does represent possible dangers and excessive costs if not dealt with immediately.    

If you would like to perform a mold inspection in your Chicagoland attic, give us a call at 312.920.9393.  For additional information, check out our website at Indoor Science  – Mold Testing

Ian Cull

Ian Cull is a nationally recognized expert in the field of indoor air quality. He is the Chief Science Officer of Indoor Science, a company he started in 2004. He speaks around the world on air quality topics and is a training provider of the Indoor Air Quality Association. Mr. Cull is a Licensed Professional Engineer (PE) and Certified Industrial Hygienist (CIH). His degree is in Environmental Engineering from the University of Illinois - Urbana Champaign. Mr. Cull has developed 50 air quality related courses for the IAQA University and is the author of the book, “Fundamentals of Mold Remediation”. In his words… “Besides being passionate about indoor air quality, I enjoy cycling, music, the Chicago Bulls, and having fun with my three kids.”

One thought on “Is Mold In An Attic A Big Deal?

    Thank you for informing me how mold, no matter where it is found or how small it is, can kill a house deal. We plan to leverage our previous house’s value in order to give us a bigger capital to buy our next house with, but I do recall seeing some mold formations in the attic before. I’ll get a mold removal expert to take care of that before we put it up for sale for sure.