Painting a Chimney Can Do More Harm Than Good

Painting the exterior of a home is not easy work. Whether you’ve hired a professional painter or are taking the DIY route, it’s important to have a plan in place, and that plan should include what parts of the home are to be painted. Here at Doctor Flue, some of our customers have asked us if it’s okay for them to paint their chimney. Usually, our answer is no, painting a chimney is never a good idea. Here’s why:

A Lesson from James Bond

If you’ve ever seen the James Bond film, “Goldfinger,” you may remember that the woman who was painted gold died because her body could not breathe through her skin. While this isn’t necessarily scientifically accurate, it’s still a good analogy of what happens when a chimney is painted. The chimney cannot breathe or let moisture escape through the barrier of the paint on the surface. This trapped moisture will freeze and thaw and cause internal damage to the chimney, which ultimately causes leaking.

So where does the moisture come from? Consider this: The exhaust from a gas appliance, such as a furnace or water heater, is 19% moisture. The moisture-filled exhaust rises up the chimney and reaches the dew point near the top. This condensation is merely a byproduct of normal day-to-day activities inside the household. In a painted chimney, that moisture cannot leave through the walls of the chimney, as it should be able it. Because the moisture is trapped, it freezes in the winter, and then breaks apart the chimney.

Importance of Flue Liners

As mentioned before, the byproducts of all combustion contain water in the exhaust. This fact mandates the proper condition of your chimney liner. Chimney liners prevent moisture from entering the structure of your chimney. If your liner is intact, the moisture should exit out of the top of the chimney, and not get trapped in the structure. To verify the integrity of the chimney lining, call Dr. Flue and ask for your free VideoScan upon your Level 2 inspection. Also be aware that moisture can penetrate the top of the chimney where the flue tile has separated from the crown or wash. If you don’t have a rain cap, moisture will enter the chimney from the outside.

So Painting a Chimney isn’t a Good Idea?

In all cases, we here at Doctor Flue will suggest not painting a chimney, but rather choosing an alternative method for preserving the structure. Consider a solvent-based vapor permeable water repellent. The selection of solvent-based over water-based repellent makes all the difference. Also, never install a water repellent that is not vapor permeable. Vapor permeability means that it will allow the moisture to come from within the structure and exit through the surface or exposed faces of the brickwork. Never install a “brick sealer”. By definition, it implies that it is not vapor permeable. Remember, you get what you pay for, so be sure to check all warranties and guarantees!

Painting a chimney prevents moisture from escaping the chimney structure properly, ultimately doing serious damage to your chimney and causing it to leak water. To learn more about what Doctor Flue can do for you, or to set up an appointment, give us a call at 800-438-3583 or send us an email at office@drflue.com. We look forward to hearing from you!

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