A chimney liner in an a historic home is essential

A problem in aging homes

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Common Chimney Problems in Aging & Historic Homes in the Cincinnati/ Northern Kentucky Market

Since at least the 1940s, the absence of a chimney liner in a chimney has been recognized as an imminent danger. Historic homes that reflect the architecture and charm of designs from our history have tremendous appeal, but with an old home comes an old chimney. In aging and historic homes, chimney problems are inevitable. This is a list of some of the most common problems associated with the chimneys in old and historic homes.

Dangers of Having No Chimney Liner

Fire safety experts continue to share a quote from that time period in which it was said that not having a chimney liner is hazardous at a near-criminal level.

In the 1950’s Chimney liners became mandatory in the U.S. Historic homes from the 1940s and earlier were usually built with no chimney liner, just bricks and not even fire bricks. These bricks are substandard for fireplaces and can create a lot of issues in a chimney. The following are the primary dangers associated with using any chimney that is not protected with a liner.

The Threat of a House Fire Due to Pyrolysis

A chimney liner protects against fire getting to combustibles which are not fuel (Like your house) When a fireplace is used without a flue liner or with a damaged liner, the exposed combustion materials go through a gradual process known as pyrolysis. As a result of pyrolysis, the structures are altered so that they combust at a much lower temperature. With no warning, a house fire will ignite and spread rapidly throughout the home.


Highly Combustible Creosote

Wood fires produce creosote, a highly flammable tar-like substance that is deposited into a chimney every time a fire is lit. If a burning ember floats up the chimney, it can cause the creosote to ignite. Chimney fires are always dangerous but especially when a chimney is not lined because virtually any chimney fire could easily spread throughout the home.

Masonry Damage

Bricks are durable, lasting a century or more if undamaged. Mortar, on the other hand, lasts only about 25 years at best. The mortar should be replaced whenever it begins to deteriorate because one of its primary functions is to protect the masonry system from moisture. If moisture intrusion occurs, winter cycles of freezing and thawing create movement in the bricks that break them down. A chimney will begin to lean and could even collapse when this occurs, though moisture can get in through other avenues besides damaged mortar as well.

Spalling is evidence of masonry damage. Spalling is when the front face of the brick pops off, and piles of debris around the chimney on the roof or the ground below provide evidence that the destructive process is occurring.

Exposure to Carbon Monoxide

Carbon monoxide is one of the byproducts of fires. Chimney liners keep this toxic combustible gases from fires contained in the chimney until they escape to the outdoors. In the absence of a chimney liner or with a broken one, these gases enter the residence. Carbon Monoxide is known as a silent killer because it is odorless, tasteless, invisible, and symptomless and escape from the deadly fumes is often impossible.


Normal settling of a house doesn’t necessarily cause foundation damage, but in older homes, there is a greater chance of damage caused by a shifting foundation due to the additional time. Cracks in the masonry is one of the symptoms of settling. When the cracks form, they begin to absorb water and then the water freezes and expands the cracks even larger.