Roof Mold: What I’ve Learned in 30 Years on the Job
We’ve been roofing in Metro Detroit for over 30 years, and let me tell you – mold on a roof is never just a cosmetic issue. We’ve seen it repeatedly: homeowners call us because they notice black streaks or patches of green fuzz on their shingles, thinking it’s just some harmless discoloration. But by the time they see it, the damage has already started. Roof mold, algae growth, and mildew don’t just make a roof look bad – they can shorten its lifespan, cause leaks, and even create health problems for your family.
How Mold Grows on Roofs
We’ve spent much time on ladders, and we can tell you firsthand that mold and algae thrive where moisture lingers. In Detroit, we get plenty of humidity in the summer, and our long winters don’t help either. Snow piles up, melts, and then refreezes, creating the perfect breeding ground for mold spores.
Shady areas of your roof, especially under overhanging trees, are the worst spots for mold growth. Those clogged gutters you’ve been meaning to clean? They trap water and keep your shingles damp. And here’s something many homeowners don’t realize: many asphalt shingles contain limestone filler, which algae and mold feed on. That’s why black streaks form over time – mold or algae literally eating away at your roof.
Once mold starts spreading, it doesn’t stop at the roof. Those airborne spores can enter your attic, leading to even more significant problems inside your home. We’ve been called in to fix roof leaks, only to find out the real culprit was a mold problem that had been ignored for too long.
The Damage I’ve Seen Mold Cause
I’ve replaced more mold-damaged roofs than I can count. Trust me – if you ignore mold, it will come back to haunt you. Here’s what we’ve seen firsthand:
Roof Leaks
Mold and algae break down roofing materials over time. Sheldon and I often peel back shingles on moldy roofs and find rotting plywood underneath. Once mold weakens your shingles, water seeps in, leading to leaks in your attic and ceilings.
Structural Damage
Over our three decades as roofers in Metro Detroit, We’ve witnessed firsthand how unchecked mold can severely compromise a home’s structural integrity. A particularly memorable case involved a residence in Ann Arbor. What began as a minor repair revealed mold infiltration extending from the roof to the foundation, necessitating an extensive and costly remediation process.
The Path of Destruction: From Roof to Foundation
Mold thrives in moist environments; a leaky roof provides the perfect breeding ground. When water infiltrates roofing materials, it doesn’t remain confined to that area. The moisture can seep into the attic, compromising insulation and wooden structures. Over time, this dampness can descend into wall cavities, reaching the foundation. The Federal Emergency Management Agency (FEMA) highlights that molds digest organic material, eventually destroying the material they grow on, and then spread to destroy adjacent organic material.
Real-World Case Studies
This scenario isn’t unique to our experience. A notable example is the “leaky condo crisis” in British Columbia, Canada. Between the late 1980s and early 2000s, over 900 buildings and 31,000 housing units suffered extensive water infiltration issues, leading to widespread mold growth and structural deterioration. The crisis resulted in an estimated $4 billion in damages, underscoring the severe consequences of unchecked moisture and mold problems. en.wikipedia.org
The Prevalence of Mold in U.S. Homes
Mold issues are more widespread than many realize. The National Institute for Occupational Safety and Health estimates that approximately 47% of U.S. homes have visible mold or a moldy odor. Water damage, often from roof leaks, is a leading cause of such infestations.
Preventive Measures
To safeguard your home from similar fates:
- Regular Roof Inspections: Identify and repair leaks promptly to prevent water intrusion.
- Maintain Gutters and Downspouts: Ensure they are straightforward to facilitate proper water drainage away from the structure.
- Control Indoor Humidity: Use dehumidifiers and ensure adequate ventilation, especially in attics and basements.
Homeowners can prevent mold from causing significant structural damage by staying vigilant and addressing moisture issues promptly.
Health Issues
Over the years, many of our customers have shared stories of persistent coughing and sneezing, unaware that mold in their homes was the culprit. While we’re not doctors, We’ve seen firsthand how removing mold can lead to noticeable health improvements.
Health Issues Linked to Mold Exposure
Mold spores are microscopic particles that can become airborne, making them easy to inhale. According to the World Health Organization, mold exposure can lead to various health problems, especially in individuals with existing respiratory conditions or weakened immune systems. Symptoms can range from mild to severe and may include:
Respiratory Problems: Inhaling mold spores can cause nasal congestion, throat irritation, coughing, wheezing, and chest tightness. These symptoms are particularly pronounced in individuals with asthma or chronic lung diseases. (WHO Guidelines for Indoor Air Quality: Dampness and Mould)
Allergic Reactions: Mold exposure can trigger allergic responses such as sneezing, runny or blocked nose, red or itchy eyes, and skin rashes. People with mold allergies may experience more severe reactions. (Health effects associated with dampness and mold)
Asthma Development: Evidence suggests that early mold exposure can increase the risk of developing asthma in children, mainly if they are genetically susceptible. (Mold exposure during infancy as a predictor of potential asthma development)
Infections: Individuals with compromised immune systems are at a higher risk of fungal infections, such as aspergillosis, caused by inhaling certain mold spores. (Aspergillus fumigatus: contours of an opportunistic human pathogen).
Health Improvements After Mold Removal
While individual experiences may vary, many people report significant health improvements after addressing mold issues in their homes:
Reduction in Respiratory Symptoms: Clearing mold can decrease coughing, wheezing, and other respiratory issues. A study published in Environmental Health Perspectives found that remediation of mold and dampness resulted in reduced respiratory symptoms among occupants. (Respiratory and allergic health effects of dampness, mold, and dampness-related agents: a review of the epidemiologic evidence)
Decrease in Allergic Reactions: Removing mold sources can alleviate allergy symptoms, improving overall well-being. The same study noted a significant reduction in allergic symptoms post-remediation. (Respiratory and allergic health effects of dampness, mold, and dampness-related agents: a review of the epidemiologic evidence)
Improved Asthma Control: For asthma sufferers, eliminating mold can result in fewer asthma attacks and better disease management. Research indicates that addressing indoor mold can lead to improved asthma outcomes. (Housing interventions and control of asthma-related indoor biologic agents: a review of the evidence)
Addressing mold problems promptly can lead to significant health benefits. If you suspect mold in your home, consider consulting professionals for proper assessment and remediation to protect your health and well-being.
Black Streaks and Roof Discoloration
Have you ever noticed black streaks running down a roof? That’s not just dirt – usually Gloeocapsa magma, an algae that thrives in Michigan’s humid summers. We’ve seen it all over Metro Detroit, from older homes in Royal Oak to newer subdivisions in Macomb. If left untreated, it can shorten your roof’s lifespan by retaining heat and degrading your shingles.
How to Get Rid of Roof Mold (The Right Way)
If you’ve got mold or algae on your roof, don’t just grab a power washer. We’ve had customers call me in a panic after blasting their shingles with high pressure, only to strip off the protective granules. Here’s what you should do instead:
- Wear Protective Gear
Mold spores are dangerous to breathe in. If you’re resolving this yourself, wear gloves, goggles, and a mask. - Use a Bleach Solution
A mix of one-part chlorine bleach and three-part water works well. Spray it on the moldy areas, let it sit for 15-20 minutes, and rinse it off with fresh water. If the mold is stubborn, adding a little trisodium phosphate (TSP) can boost cleaning power. - Keep Your Roof Dry
Since mold thrives in moisture, preventing water buildup is key. We always tell homeowners to clean their gutters regularly so rainwater drains correctly. If your attic feels damp, you might need to improve ventilation or install plastic sheeting to prevent moisture from seeping in. - Trim Overhanging Trees
We love trees as much as anyone, but if they’re shading your roof and dropping leaves into your gutters, they’re part of the problem. Cutting back branches lets sunlight dry out your shingles faster, keeping mold at bay. - Call a Pro If It’s Bad
If mold has already caused damage or keeps coming back, don’t mess around – call in a roofer who knows what they’re doing. We’ve had to do full roof replacements because homeowners ignored mold for too long. Getting professional mold remediation early is much less expensive than replacing your entire roof.
Why Removing Roof Mold is Worth It
Fixing a moldy roof isn’t just about looks—it’s about protecting your home and family. Here’s why getting rid of mold is a smart move:
✔ Saves money on repairs – A little roof cleaning today can prevent a costly roof replacement.
✔ Keeps family healthy – No more breathing in mold spores.
✔ Boosts home’s value – Curb appeal matters, and black streaks aren’t a good look when trying to sell.
✔ Extends your roof’s lifespan – Keeping mold and algae off your shingles helps them last longer.
Final Thoughts from a Roofer Who’s Seen It All
Mold on your roof isn’t just an eyesore-it’s a warning sign. We’ve seen minor mold problems become big headaches, and our team has seen homeowners save themselves thousands by dealing with it early. Regular maintenance, proper ventilation, and keeping your roof dry are your best defenses against mold.
If you’re in the Detroit area and think your roof might have mold, don’t wait until it’s too late. Take a look, call a pro if needed, and keep your home in shape. And if you ever want to talk roofing or hockey, we’re always happy to chat.
