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5 Common Causes Of Attic Mold

5 Common Causes of Attic Mold

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The thought of mold appearing in your home can be quite scary. Mold can be harmful to your health and that of your family. It can trigger mold symptoms and allergies, worsen asthma, and cause various health problems. What’s even scarier is that many homeowners might not even realize they have mold until it becomes a real threat to their health and property.

Mold loves moisture, and attics are often damp places. Mold often grows in attics because they’re hot and humid, and have plenty of wood for mold to feed on. Since most homeowners don’t check their attics often, mold can grow undisturbed for years, which is a big issue!

Our experts at Reagan Environmental have come up with 5 common causes for mold in your attic, and methods to test and remove mold from your property. Schedule a free consultation with us, we can answer any unanswered questions that was not answered about attic mold in this blog.

What Does Attic Mold Look Like?

This is mold growth on insulation in the attic of a home in Houston, texas
Mold On Insulation
This is mold growing on plywood in a home
Mold On Plywood
This is mold found on an air duct in the attic in houston texas
Mold Growth On Air Ducts In The Attic
This is mold growing on roof decking, from moisture build-up in the attic
Mold On Roof Decking

Houston, Texas is a very humid place, and in any humid environment mold will thrive. For homeowners who found that they have mold but neglect getting a mold test and removing the mold, there can be some consequences. Below are some of the common consequences of neglecting mold:

Mold Spreading To Other Areas

If you don’t take care of mold in your attic, it can easily spread to other parts of your home. Mold spores can move around in the air or stick to things like clothes or pets, spreading to new areas and making the problem worse. Mold spores can also spread through vents and potentially infest a large part of your home.

Decrease In Property Value

Having mold in the attic can significantly reduce the value of your property. When potential buyers discover mold, it often raises concerns about the overall condition of the home and potential health risks. Mold can be a deal-breaker for many buyers, causing them to either walk away from the sale or negotiate a lower price. Even if the mold issue is addressed before listing the property, its previous presence can still affect the perceived value.

Structural Damage

Mold grows in attics where there’s moisture and organic materials like wood. When mold spreads on wood, it breaks down its structure, weakening it. This process, called decay, can damage the attic’s structure over time.

If left untreated, mold can lead to costly repairs and make the attic unusable. To prevent this, control moisture, improve ventilation, and fix leaks as soon as you can.

What Happens If You Don’t Treat Attic Mold?

5 Common Causes Of Mold In Your Attic

Cause #1: Roof Leaks

Many issues can occur near the flashing or where the roof meets vertical surfaces like vents or chimneys. Roof leaks often happen because of missing, deteriorated, or improperly installed flashing, as well as other spots where water can get in. When the roof gets old, it’s more likely to leak. Homeowners usually can’t see these leaks, they can linger for a long time, and in that time, mold is likely to grow in your attic from the moisture.

Cause #2: Poor Roof Ventilation In Your Attic

Insufficient ventilation in the attic can lead to excess moisture, especially around the roof framing and sheathing. Blocked soffit vents are also a common reason for poor ventilation. Debris like leaves, bird nests, or blown-in insulation can clog these vents, disrupting airflow. Soffit vents are essential for air circulation in the attic.

When ventilations is blocked, warmer damp air will have no where to exist out from your attic and that moisture is the catalyst for mold growth.

Get peace of mind knowing your space is mold free.
Schedule your mold inspection today!
Get peace of mind knowing your space is mold free.

Cause #3: Exhaust Fans Vented In The Attic

Exhaust fans should be vented outside the home, but it’s not uncommon to find them improperly installed. If an exhaust fan lacks a duct or if the duct becomes disconnected, warm, humid air is released directly into the attic. This creates the perfect conditions for mold growth. It’s crucial to fix this problem by redirecting the vents outside.

Cause #4: Attic Insulation

Attic insulation has two important roles: saving energy and preventing mold. It slows airflow, which reduces heat loss in the attic. Without enough insulation, airflow increases, leading to condensation on cold surfaces like the roof.

This moisture buildup creates ideal conditions for mold growth. So, maintaining proper insulation levels is crucial for a mold-free attic.

Cause #5: Gaps Of Ceiling Openings In The Attic

Unsealed openings in ceilings, like those around exhaust fans and lights, can let warm air escape into the attic. It’s important to seal these gaps to prevent mold growth in the attic. Although attics aren’t usually living spaces, mold in the attic can still be a problem. Mold spores from the attic can enter inhabited areas if there’s negative pressure in the property. 

Attic mold can also indicate other issues like water damage or mold in living areas, which could lead to expensive repairs later on. Regular inspections can help catch these problems early. If you suspect issues in your attic, it’s best to consult with a licensed mold professional like Reagan Environmental for a thorough assessment.

Although, mold is common in attics, it can be harder to see under the insulations and smaller crawl spaces within the attic. As a result, there are several methods we use to do a mold test;

Air Sampling:

This method involves collecting air samples from the attic and analyzing them to detect the presence of mold spores. Air sampling can help determine the concentration and types of mold spores present in the air in the home and in the attic. Samples are usually collected using specialized equipment such as air pumps and filters, and then analyzed in a laboratory to identify and quantify mold spores.

Surface Sampling:

Surface sampling involves taking samples from various surfaces in the attic, such as walls, ceilings, or insulation. Samples are collected using swabs, tape lifts, or other sampling devices and then analyzed in a laboratory to detect the presence of mold growth. Surface sampling can help identify specific areas of mold contamination and determine the extent of the problem in your attic.

Bulk Sampling:

 Bulk sampling involves collecting samples of materials such as wood, drywall, or insulation from the attic. These samples are then analyzed in a laboratory to detect the presence of mold growth and identify the types of mold present. Bulk sampling can provide valuable information about the severity of mold contamination and help guide remediation efforts.

These mold testing methods are commonly used to assess mold levels in attics and determine the appropriate course of action for remediation. Each method we use has its advantages and limitations, and the choice of testing method may depend on factors such as the suspected extent of mold contamination and the specific goals of the testing process.

Learn more from our mold testing through out page here.

How Do We Test Mold In Attics?

Finding The Source:

During a mold inspection and testing, Reagan Environmental uses several tools to find the source that is causing the mold; tools such as:

  1. Moisture meters: They measure moisture levels in materials.
  2. Thermal imaging cameras: They detect temperature changes that may indicate moisture or hidden mold.
  3. Borescopes: These cameras can see into small spaces like walls.


This involves inspecting the affected areas thoroughly to pinpoint the underlying cause, such as water leaks, poor ventilation, or high humidity levels. Finding the source can really help use create the best protocol and steps for remediating the mold and making it safe to live in your own home.

Removing Mold From Your Attic:

Once the source is identified, mold remediation specialists use a combination of tools and techniques for an attic mold removal. This may include:

  • Scrubbing: Physical removal of mold from surfaces using brushes, scrubbers, or other cleaning tools.
  • HEPA Vacuums: High-efficiency particulate air vacuums are utilized to capture mold spores and prevent their dispersal during cleanup.
  • Antimicrobial Treatments: Application of specialized solutions to eliminate mold and inhibit its regrowth.
  • Removal of Contaminated Materials: When necessary, mold-infested materials such as drywall or carpeting may be safely removed and disposed of to prevent further spread of mold.


The best attic mold treatment is to get it remove as soon as possible by skilled professionals who can detect the source of the mold problem. Understanding what’s causing mold growth is very important, because mold can come back if the source, whether it’s roof leaks, poor ventilations or gaps in your sealing is not dealt with.

Doing A Post-Remediation Inspection:

After the mold removal process is complete, a thorough inspection is conducted by Reagan Environmental to ensure that all mold has been successfully removed. This final inspection, called the “post-remediation inspection,” is essential for verifying the effectiveness of the remediation efforts and ensuring the health and safety of occupants.

Reagan Environmental is a trusted environmental company in Houston, Texas. We have 15+ years of experience dealing with mold. Contact for questions related on mold and indoor air quality issues you might have.

How To Remove Mold In Your Attic?

How Much Does Mold In Attic Removal Cost?

What Are The Common Mold Species Found In Attics?

The cost of mold removal in an attic can vary depending on factors such as the extent of the mold infestation, the size of the attic, and the methods used for remediation. On average, professional mold remediation services for attic mold removal can range from a few hundred to several thousand dollars.


Some common mold species found in attics include:

  • Aspergillus
  • Penicillium
  • Cladosporium
  • Stachybotrys (which is black mold in your attic)
  • Alternaria

Is Mold In Attic Dangerous?

Mold in the attic poses significant risks for various reasons. Firstly, exposure to mold spores can result in allergic reactions, respiratory problems, and worsen existing health issues, especially for those with allergies or weakened immune systems.

Secondly, mold can weaken and damage attic materials like wood sheathing, rafters, and insulation, potentially undermining the structural stability of the attic and the entire house. Additionally, mold growth can cause unsightly discoloration, unpleasant odors, and harm to items stored in the attic, necessitating expensive repairs and replacements.

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When you book an inspection with Reagan Environmental, you’re not just putting your trust in our service; you’re reclaiming peace of mind.

Our highly trained and experienced team of mold experts will conduct a detailed inspection of your property, identifying any potential environmental risks that may be lurking beneath the surface.

Whether it’s mold, lead, asbestos, or any other environmental concerns, Reagan’s got you covered.

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