Chimneys are a vital part of any house and they should be built and secured properly if you don’t want to have any problems with them in the future. The chimney’s primary function is to connect with furnaces, heating stoves and other burning installations such as fireplaces which we’ve also shown how you can install, here.
Figuring out how to build a chimney can be even more daunting, however, regardless of whether you want to use brick, masonry or metal, so let’s go over the step-by-step process here:
Consult with your local construction codes before you do anything
For starters, you can visit the NFPA website for some insight as most states’ codes are based on the National Fire Protection Agencies 211 standard but there are also differences between different states. The basic things to remember are that chimneys should be at least 3 feet tall and at least 2 feet taller than anything around them. There should also be at least a 2-inch clearance between the chimney and any combustible materials.
Choose the material
Masonry, brick blocks, concrete blocks, and metal are all viable options. With brick and masonry chimneys you’re going to need to figure out and plan how much material you’re going to need and with metal chimneys, you’ll need to calculate the distance between the stove or fireplace and the end of the chimney so you can order the exact sizes of metal sheets you’ll need.
If you’re wondering how much does it cost to build a chimney, the materials used to play a part in this. The overall cost depends on too many additional factors but the short of it is that masonry and brick chimneys cost more over time and are less efficient but are typically more durable than metal chimneys.
Figure out what you’re going to use the chimney for
Different chimney designs and materials are suitable for different venting needs. A gas range chimney may work for a gas furnace as well but not for a wood-burning fireplace, for example.
Now, onto the building itself. The process for how to build a block chimney, how to build a concrete block chimney or a masonry chimney is pretty similar so we’ll just describe them all in general below. Metal chimneys are even easier to construct and follow the same template.
Build the smoke chamber
Chimney building starts from the ground so, first, you’ll need to build the smoke chamber over whatever burning device you’re going to use. If you’re building a chimney for a fireplace, for example, the smoke chamber is what large opening of the chimney that’s right above the fireplace. It should fit the venting needs and dimensions of the fireplace or stove and gather all the smoke easily. With metal chimneys, the smoke chamber looks almost exactly like the rest of the chimney but with masonry or brick chimneys it’s significantly wider. Make sure that the sides are straight and stable, and that the base is properly secured.
Build up the walls of the chimney
Just continue building the chimney up from the smoke chamber with whichever material you’ve chosen and at whatever width is suitable for your home and needs. Make sure the sides are level and every part of the chimney is 100% secure.
Build the flue and the outside of the chimney
This can be either a brick or a metal pipe that connects the chimney with the roof. You can line it with clay or ceramic tiles and use concrete liners to cast them into place.
Add chimney flashing
This is one of the important last steps to protect your chimney from water, snow, and other environmental factors. Here’s a quick article with some of our Chimney Flashing Installation Tips.
Add a cap to your chimney
Last, simply add a cap on top of the brick or metal flue housing. The cap should be placed at least 2 inches above the chimney’s opening and have a drip edge to protect it from water and debris. Aside from that, it can be whatever design you want.
