Many older homes were built before modern building codes required chimney liners. Peeking inside an unlined flue of an early 1900’s home and you will probably notice burn marks, cracks and other damages indicative of one or more chimney fires. Today, most building codes require chimney liners. But they don’t last forever, and the liner will eventually need to be repaired or the chimney relined.
Why You Need a Chimney Liner
An unlined chimney is an extreme fire hazard. It exposes the masonry to extremely high temperatures and increases the risk of a chimney fire. The high heat can also damage the masonry surface allowing carbon monoxide fumes to enter your living space. Testing conducted by the National Bureau of Standards more than thirty years ago revealed that unlined chimneys pose a significant fire and safety risk to the structure and its occupants.
The chimney liner serves four purposes: to keep flames away from combustible materials; to direct smoke and fumes through the vent; to protect the structural integrity of the chimney and increase the heating efficiency of your fireplace or heating stove.
Clay tiles are the most common type of chimney liner. Clay is an inexpensive, durable, and fire-resistant material which are the reasons for its popularity. They are available in rectangular, square and circular shapes and a range of sizes. The tiles need to be correctly sized for the chimney to minimize creosote accumulation. The size and shape of the flue will determine the number of tiles required.
The chemicals produced during combustion can cause clay tiles to corrode, mainly from gas heating appliances. And a water leak can also erode the socket joints causing tiles to crack or fall off. Also, its effectiveness is reduced when tiles are not installed perfectly straight and flush against each socket joint. Although clay tiles are relatively inexpensive, it is very labor-intensive to install. So, if more than a few tiles need repairs, it will be more cost-effective to reline the chimney.
Concrete flue liners share many of the same advantages and fire-resistant properties of clay tiles but don’t corrode when using gas fuels. There is also less creosote accumulation when heating with wood-burning appliances. They are also referred to as cast-in-place liners because the cement is poured directly into the chimney. When the cement cures, it hardens into a smooth surface without any seams. It also increases the structural integrity of the chimney, making it an excellent choice for relining older flues. Like clay, cement is porous, and cracks can develop in the surface, especially during settling or if low-quality cement was used. Also, water leaking into the flue can lead to deterioration of the liner.
U.L. listed stainless steel liners are considered among the highest quality materials for relining chimneys regardless of fuel source. Steel liners have superior fire resistance qualities and unlike clay or cement, are also resistant to water, pests, and mold. Like other chimney liners, they require professional installation and must be correctly sized for the chimney. High thermal insulation is usually installed with the liner to increase performance and safety. They are also easy to clean and maintain, making them well worth the investment.
A chimney liner insulates the chimney protecting the integrity of the structure while maximizing heat from your fireplace to keep your family safe and your living space warm and cozy. Annual chimney inspections and cleaning can also help extend the life of your chimney liner.