How Water Affects Your Chimney

In a word or two, rather poorly.  Keep in mind that your chimney’s exterior is likely made from brick or other masonry, held together by mortar.  Inside is the flue, commonly made from terra-cotta clay or metal.  The damper, to control the draft, is also metal, usually cast iron.  Your chimney has been designed to withstand high temperatures and to safely exhaust the smoke and combustion gases (including carbon monoxide).  Let’s look more closely at how water can negatively impact your chimney.

Brick, mortar, concrete, even stone facing are all porous materials that will absorb water.  When temperatures fall below freezing, that water expands as it turns to ice.  Rising temps melt the ice, which contracts.  These cycles of freezing and thawing, expansion, and contraction, cause cracks to form in masonry materials.  Over time, mortar can chip and crumble.  Bricks and concrete can show the effects of spalling, the chipping, and flaking away of outer surfaces.  It is important to be aware of this as cracked and damaged masonry is perhaps the most expensive chimney repair.

Water can cause problems inside a chimney, too.  A good chimney cap will keep water from entering your chimney.  It also keeps burning embers and sparks from exiting the chimney and perhaps landing on your roof or the roof of a neighbor and prevents birds and small animals from nesting in the chimney. A good chimney cap also acts as a windbreak, reducing utility expenses by minimizing drafts around the fireplace. Without one, water can seep into clay or tile, slowly eroding them away.  Water could also pool inside your stove or fireplace.

It is worth knowing, with certainty, that our chimney cap is doing it’s job.  After all, it’s way up there on top of the chimney, subject to whatever Mother Nature chooses to throw at it.  High winds and stormy weather can take a toll on this critical part of the chimney, eventually reducing its effectiveness.  If your home is old enough, the chimney may have been built without a cap of any kind, or the original may have deteriorated to the point where it no longer provides the protection that it once did.  After all, without a full assessment, it can be tough to decide how best to proceed.

We hope you have found this information helpful, particularly if you suspect that your chimney is not quite performing as well as it once did, or if you have recently moved into a “new-to-me” home and want to be sure that your chimney is working both safely and efficiently.

Burlington Fireplace
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262-763-3522