10 Common Chimney Issues

Old Flashing On A Chimney


January 10, 2020

Here are the top 10 common chimney issues we see.

Creosote Buildup

Creosote is a natural by-product of burning fuel. However, when you are burning improper fuel such as wet or unseasoned wood, you may find yourself with more than a normal amount of creosote build-up. This build-up can actually create an issue whereby we may suspect a cracked liner but are not actually able to verify it without a more thorough cleaning. This tends to happen when the creosote is glazed.

Shiny Glazed Crosote
Glazed Creosote on a chimney flue.

Bad Flashing

By bad flashing, we don’t just mean older flashing that is very old and due for a replacement. We mean flashing that has either pulled away from the chimney structure or was flat out improperly installed to begin with. This generally happens when you have a green roofing crew who takes a swing at chimney flashing.

Old Flashing On A Chimney
This chimney has flashing that is pulling away. We can either fix or replace this flashing.

Cracked Flue Tiles

It never surprises us when we find a cracked flue tile. This can happen when you have a chimney fire, or when the heat causes the tiles to expand unevenly, placing pressure on one side of the tile and cracking it.

Cracked Flue Tile
This flue tile is cracked from thermal shock.

Chimney Crown Cracks

This very common problem is caused mostly by improper installation and by natural aging. Generally, we find that there is no expansion joint on the top flue tile, or that the crown was made improperly or out of the wrong material.

Cracked Chimney Crown
The crack in this crown is wide enough to let water enter and cause further damage. Attempts to fix with caulk are more of a band-aid than a permanent fix.


When a brick face begins breaking off, this is called spalling. This can happen from water penetrating the bricks which are naturally porous. Once this water freezes it expands and it has nowhere to go and so it breaks your bricks.

Spalling Bricks On A Chimney
This chimney has several bricks where the face is breaking off. This is called spalling and is typically caused by water penetrating the bricks and freezing.

Damper Issues

Dampers are not complicated devices but they do have issues. Often we find that the dampers are just off track and just need to be reset.

Chimney Damper
Another view of a Damper.

Deteriorated Mortar Joints

In many of the chimneys that we inspect we find that the mortar joints have deteriorated or are missing. This happens because of water and the freeze/ thaw cycle.

Missing Mortar Joints in a Chimney Flue
This chimney’s flue has missing mortar joints which fails NFPA 211 14.9

Smelly Chimney

Many of the customers call us not because of safety concerns but because their chimney produces a pretty pungent smell. This is creosote buildup in the chimney and it gets worse in the summer. It’s really bad when you have negative air pressure to boot.

Negative Air Pressure

We find that a bunch of our customers make comments about smoke when starting fires or feeling like there is a cold downdraft all of the time. This can be caused by negative air pressure, whereby your home wants to “suck air” in. It will usually take the easiest path, which is your chimney.

Water Damage

 A chimney’s natural enemy is water. Unfortunately, once water gets in and wreaks havoc, your only option is repair or rebuild. The best thing to do here is to ensure your chimney has the proper water repellent professionally applied on a regular basis.

Written By Steve May

Steve May founded Chimney Works And Rocky Mountain Stoves in October of 2001. Steve is an entrepreneur at heart, and avid outdoorsman, and a proud father of 5.

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