Company Blog

What Are Those Ugly Stains On Your Chimney?

Staining on your chimney may be one home improvement project that can prove to be difficult to figure out by yourself. Discoloration on a What Are Those Ugly Stains On Your Chimney - Greenville SC - Blue Sky Chimneychimney doesn’t usually happen because of old age or use. It’s typically a warning that there is an underlying problem. The color of the staining on your chimney can give you a clue as to what the problem is.

So…what color are the stains?

Black, Brown or Green Stains

These stains are usually located closer to the top of the chimney or around “shoulders.” At times they may extend top to bottom over just part of the surface of the chimney. While it’s possible that some black or brownish stains at the very top can be from condensate dripping off a cap, it is more likely (especially where there is no cap) these stains are a sign that mold, mildew and/or algae is growing in the chimney. Mold, mildew, and moss growing on the chimney surface are caused by excess moisture in the chimney structure. It could be growing on the chimney because of a water entry problem due to a clogged gutter causing overflow to run down the chimney. Or it may also be growing on the chimney because of excessive water absorbing into the chimney due to soft brick or mortar or holes in the mortar joints. This along with slow evaporation will lead to vegetative growth that will eventually undermine the mortar of the brick structure. If you notice these dark stains, it is a smart idea to call on a trained professional to evaluate your chimney to identify the source of the problem and recommend

Reddish Rust-like Stains

Rusty reddish stains on the chimney are a sign that a metal chimney component, like a chimney cap or chase cover, is rusting. Rusting of these components will produce pitting and flaking of the metal and will eventually develop holes that will allow damaging water to get into your

White Stains (Efflorescence)

White powdery staining is called efflorescence. When water evaporates out of masonry, it leaves behind whitish salt deposits. The staining itself can sometimes be removed, but it is a sign of a more serious condensation or water absorption problem and will likely return if the
problems causing it are not corrected. Water absorption/intrusion of some kind is the root problem and eventually deteriorates bricks and mortar or causes other damage, if it is not stopped. Along with weakening the structure of your chimney, water damage can spread to
your home ruining walls, ceilings and floors.

Pretty much any of the stains can be traced back to a water problem of some kind. Regular inspections to determine necessary maintenance and replacement of deteriorating products will protect your investment and help avoid unexpected costly repairs. Let our trained professionals here at Blue Sky Chimney Sweeps|Bless Your Hearth help determine how water is getting into the chimney and solve the problems before things escalate.

3 Ways Water Ruins Your Chimney

Chimneys sure are high, but they are not necessarily dry. As one of Upstate South Carolina’s premier chimney service companies, those of us at Blue Sky Chimney Sweeps see water as your chimney’s biggest adversary.


You might be able to leave a leaky faucet alone for a while, but a leaky chimney is another story. Small chimney leaks can very quickly lead to big chimney leaks, and big, expensive problems.

Unfortunately, it’s not at all difficult for water to find its way into a chimney that has not been adequately protected from the elements.

While we can certainly find resolutions for your leaking chimney, your best bet will always be to prevent leaks from the beginning. Water intrusion left unmanaged, can cause significant damage to the chimney structure as well as areas adjacent to your chimney. This damage is often expensive to repair.

Here are just a few ways that water can harm your chimney:

  • Water weakens your chimney’s masonry. There are a number of ways that your chimney brick and mortar may react to rainwater.
    Crumbling, cracking, or bricks falling apart altogether.
    Spalling (when the face of the bricks appears to have popped off).
    Holes in header joints
    The more your masonry breaks down in this way the more easily water will be able
    to get into your chimney and, possibly, into your home.Water creates cracks and/or voids inside and out.
  • Water creates cracks and/or voids inside and out. Water can cause both on the inside and the outside of your chimney.
    The relentless freeze/thaw cycle can also cause the bond to break between the brick and the mortar.
    Water washing over the exterior surface of the brick can erode out thin mortar joints.
    Water washing over the inside of your chimney can cause gaps to develop between the flue tiles. This would allow toxic gases attack the brick and mortar of your chimney from the inside out. In some cases it could cause the gases to leak through into your living space instead of venting safely outside.
    In some cases the damage may permit water to get inside your home, where it can stain the walls, ceilings, and floors around the chimney.
  • Water can cause mold, mildew, and lichen to grow on the exterior of the chimney.

If you find yourself dealing with water issues with your chimney, call Blue Sky Chimney Sweeps|Bless Your Hearth at (864) 682-5422 or fill out our online form to make an appointment with us today. We can help!

We are proud members of the South Carolina Chimney Sweep Guild, the North Carolina Chimney Sweep Association, and the National Chimney Sweep Guild. We are certified by the Chimney Safety Institute of America and the National Fireplace Institute.