Ask a Contractor - Average read time: 2 minutes

My roof has developed dark stains on along the edge and up around my chimney. Neighbor says it is mold? I would like to know what it is and how I can clean it off of the roof?

Tom – Livonia, MI


Chimney stains are a common problem for homeowners. Stains can form both on the interior and exterior of the chimney. While you are seeing dark brown or black stains around your chimney, other homeowners may also notice white or light colored stains as well. These stains can be the sign of normal wear and tear on a home but it can also be a warning sign for a more significant issue.

Your neighbor may very well be correct when he or she said that the stains could be linked to mold. Dark stains along a chimney are often a sign of water intrusion and water damage. It’s important that both the interior and exterior of the chimney is thoroughly inspected. A professional inspector will pay particular attention to any cracks or leaks along the chimney. In addition, the overall safety and condition of the structure will be assessed.

Mold thrives in damp, dark environments with poor ventilation. Therefore, your chimney is the perfect place for mold to call home if you do not have the best ventilation in place. If it is determined that you have a water or mold issue on or within your chimney, it will need to be removed and thoroughly washed with specific tools and cleaners. It’s not something we recommend doing yourself since it’s possible to overlook areas which can lead to more serious damage to your home or health issues. If you need extensive mold removal, please seek a mold removal specialist.

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Now, it is possible that the dark stains you see aren’t due to water damage or mold at all. Sometimes, black stains can appear on the chimney as soot washes off the chimney cap. There could be a build-up of soot if your chimney is not cleaned regularly. We recommend having your chimney cleaned and inspected regularly to look for any structural issues or damage, improve your chimney’s overall efficiency, and reduce the risk of fire or carbon monoxide entering the home.

The dark stains on your chimney could very well be a sign of age, but it can also be a result of poor ventilation or structural damage. At Pro Home Improvement, we help Michigan homeowners stay safe with roofing and chimney inspections year round. Give us a call at 248.556.5839 or contact us online to schedule an appointment today for a no-obligation inspection and estimate.

If you have any other questions about future home projects or anything general repair advice, feel free to drop us a message on our ask a contractor page.

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