Mold in Attic: How to Detect, Prevent & Remove It


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Mold in attics is a common problem that can cause serious damage to your home. Many factors, including humidity levels and lack of ventilation, can cause mold growth in an attic. If left untreated, mold will spread quickly throughout the space.

By understanding what causes mold growth and taking proactive measures against it, you can protect yourself from costly repairs due to water damage or black mold growth caused by unattended moisture issues within your attic spaces.

Causes of Mold in Attics

Mold growth in attics is a common problem for homeowners. It can cause health risks, property damage, and an unpleasant smell. Knowing the causes of mold in attics can help you take steps to prevent it from happening in your home.

Mold feeds on organic matter, including the lumber that is the structure that supports your entire roof system. It will not end well unless you take action if your attic is infested with mold. Mold is most literally eating your house and home.

Let's talk more about humidity, leaks, ventilation, and how each affects the health of your roof and roof structure.

High Humidity in the Attic

High humidity levels are among the most common causes of attic mold growth. As we all know, heat rises, and no matter what time of year it is, heat goes straight into the attic. To reduce humidity levels, ensure that your attic is properly ventilated and insulated by consulting with a professional roofing contractor.

To get rid of moist air in your attic, make sure you have adequate baffles and turbine roof vents on your roof, or power vents installed.

Roof Leaks and Bad Ventilation

Leaky roofs or inadequate ventilation can also lead to mold growth in attics as moisture builds up over time without being able to escape through proper ventilation systems or roof repairs.

Suppose you suspect leaks from your roof into your attic. Have a professional roofing contractor inspect it immediately so they can identify any potential leaks and get them repaired immediately. It will only get worse until the leaks are corrected and sealed up.

Increasing ventilation in the attic, when it doesn't need it, can increase moisture issues and decrease the effectiveness of whatever insulation you have installed. Your local roofer can help ensure you have the proper ventilation. The cost of proper ventilation is much cheaper than the repairs and processes necessary to correct mold and moisture issues in the long term.

How to Prevent Mold Growth in Attics

Mold growth in attics can be a serious problem for homeowners, and it's most typically due to high humidity, roof leaks, or improper ventilation.

Here are a few tips on preventing mold growth in your attic:

  • Keep humidity between 30 and 50%; higher than 50%, and you're asking for mold
  • Check for damage or blockages in the ventilation and repair them as soon as discovered
  • Check the insulation to make sure it isn't getting wet from leaks or condensation
  • Use closed-cell insulation or Rockwool insulation instead of fiberglass batting, denim, or other insulation materials friendly to mold growth.
  • Exhaust fans should vent to the outside, not into your attic
  • Seal gaps and cracks that let moisture in
  • Repair roof leaks immediately



How to Detect Mold in Attics

Visual Inspection

One way to detect attic mold is by visually inspecting the area for discoloration or musty odors. If you notice any dark spots or patches on walls, ceilings, or other surfaces, this could indicate the presence of mold. These spots are typically dark brown or black but could also be green or other colors. Any discoloration on the surfaces in your attic is suspect.

If you see over ten sq ft of mold growth, stop what you're doing and call a professional for mold testing.

Testing for Air Quality and Moisture Content

Testing air quality and moisture content levels in your attic can help determine whether there are elevated levels of mold spores. A professional inspector will use specialized equipment to measure these levels accurately and provide recommendations based on their findings.

Suppose you suspect there may be hidden areas where mold has grown undetected due to poor visibility or inaccessible spaces, such as behind walls. Hiring a professional mold inspector with experience dealing with indoor air quality issues is recommended.

They will have access to advanced testing equipment and labs, which they can use to identify even small amounts of airborne spores which would otherwise go unnoticed without specialized tools and expertise.

Note: Air quality testing is not to see if mold spores are present. Mold spores are always present in the air anywhere on Earth. They are looking for specific types of mold that far exceed normal parts per million in any given air sample. Basically, it's the concentration levels of specific mold spores in the air they are interested in. There are known safe, or “normal” ranges.

Removing Mold from Attics

How mold is removed depends on how much mold there is and where it's located. If it's on or in the insulation, the best solution is to replace the affected insulation. But, if it's on the inside of the roof structure on the plywood, you will need a professional mold remediation company to take care of it.

Dry Ice Blasting

Dry ice blasting is one of the most recent technologies for removing mold from surfaces like plywood in the attic. This is the process of taking pelletized dry ice that is near -110°F and used to blast the mold away. This requires specialized equipment and protective gear to do safely.

Mold Encapsulation

Mold can be encapsulated with special paint when it can't be removed from the building's structure. Only when the mold can't be removed should it be encapsulated. Surfaces like drywall, flooring, etc can be easily removed and replaced. It's difficult to replace your roof plywood, trusses, etc.

This doesn't actually remove the mold; it simply stops it from being able to get into or out of the treated surface, and shuts off access to moisture and food sources.

You Shouldn't Try To Remove Attic Mold Yourself

Removing mold from the attic can be dangerous because attics are dangerous places to work due to the possibility of misstepping and falling through the drywall into the room below. Homeowners shouldn't attempt it in most situations because even professionals still have accidents.

We don't recommend DIY mold removal from your attic; a professional mold remediation company should be called due to the danger of falling through the ceiling and the lack of proper equipment to do the job.


Mold in attics can be a serious problem, but with the right knowledge and precautions, it doesn't have to be. Taking steps to prevent mold growth in your attic is key, as well as being able to detect any signs of mold early on.

If you do find yourself dealing with a mold infestation in your attic, make sure you call a professional water damage restoration and mold remediation contractor who can help safely remove the mold from your home instead of trying to remove it yourself. As long as you stay proactive and regularly inspect your attic space, you'll be ready when mold eventually strikes.


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