In what situation is a flexible chimney liner preferred?

A flexible chimney liner is preferred when retrofitting an existing chimney primarily due to its ability to adapt to the existing structure. Retrofit projects often involve older chimneys that may not have the straightest or most uniform flue configuration. A flexible liner can be easily maneuvered into these irregular shapes, providing an efficient and effective solution for venting exhaust gases safely.

Additionally, flexible liners are typically lighter and easier to install than rigid liners, making them a practical choice for homeowners looking to upgrade or repair their existing chimney systems without extensive renovations. This adaptability also helps to tackle issues such as moisture intrusion and creosote buildup, improving overall chimney function and safety.

In contrast, building new chimneys generally allows for the installation of rigid liners, making flexibility unnecessary. Gas appliances often have specific venting requirements that can be met with various options, and increasing chimney diameter would typically require a different approach, such as using a rigid liner or building a new masonry structure.