Components of a Masonry Chimney

This brick chimney has a concrete crown and two terra cotta flues and stainless steel caps.

Few people take the time to do more than glance at their chimney, and see it as only a feature of their house. In reality, the chimney is an engineered structure that plays an important part in the safe and proper operation of your heating appliances.

A chimney consists of an outer wall, usually made of brick, stone, or concrete. In some modern construction, a chimney chase is constructed as a structure attached to the building. In this article, we are discussing masonry chimneys. To read about chimney chases, please go here.

Inside the outer wall is a liner generally made of terra cotta.  The liner can be square, rectangular or round.  Some chimneys may have multiple liners, usually two but even as many as three or four.

At the top of the chimney is the crown.  This is usually a slab of stone or concrete.  Fitted over this may be a chase cover.   This covers the entire top of the chimney and has cutouts for the chimney liners.

At the top of the chimney is the chimney cap.  This is designed to fit over the flue liner, and may encompass a large portion of the crown.  It is to keep out water and snow.  It also may have a mesh material covering the side openings to prevent debris, birds, and animals from getting inside the chimney.

It’s important to understand a chimney is engineered and designed to function with your heating appliances whether they are a furnace, stove, water heater or fireplace.  Besides venting, a properly designed and constructed chimney provides draft which causes smoke and gases to be drawn up and out of your home.  Therefore, it’s imperative to keep your chimney clean and in good repair to prevent damage to your home, leakage of toxic gasses into your living quarters, and your heating appliances working safely and efficiently.