Guide to Building a Chimney

Please note: My boyfriend, Jon, who is a professional mason, has provided this information to me to share with all of you. I hope that it provides valuable information to you as well.

This “how-to” article is for experienced masons who already know the basics of laying brick. This article will just provide the details of chimney building. If you are a beginner, and do not know how to lay brick or block, please consider hiring a professional for your chimney project.

Materials needed for this job include: brick and block of choice, firebrick, damper, mortar, sand, flues, 4 foot level, 2 foot level, square, trowel, striker, brush, and scaffolding

Once you’ve gathered your materials, start by laying out the firebox by using the standard measurements, 36 x 36, with a depth of 18 inches. You must use fire brick in the fire box. Do not use regular brick in firebox, this is not safe. Once the firebox is finished, start to build the outside walls with brick or block .After you build the outside wall as high as the firebox, which is about three feet high, fill in between the wall and the firebox with fill brick and mortar.

The next step is setting the damper and filling around it. Make sure it’s air tight so no smoke can get out. The damper is the most important part of building a chimney because that’s what controls the smoke draft up the chimney.

As you continue building the chimney, the next step is to build the smoke chamber. The smoke chamber closes the damper from 36 inches to an 8 x 8 opening so the flue can be set on.

After the smoke chamber is finished, set the first flue, then level and plum. It’s is important to do so because that’s the base. From here on out, the steps are pretty simple. Keep building the chimney up. Once the chimney is close to the peak of the roof start designing the chimney the way the owner wants it. Make sure the top of the chimney is 2 feet past the peak of the roof, because that’s the code. Finish filling up to the top, and then cap it off so the only thing open is the top of the flue.

The hearth is the next step of the chimney. Begin making the design that is wanted by owner, lay brick up to the top off the mantle, or in some cases to the ceiling. The hearth is the last step to do after finishing the brick work. You began cleaning the damper from extra mortar that has fallen down as you were building the chimney top. Always make sure the damper opens and closes before starting a fire.