This post may contain affiliate links so I earn a commission.
If you want to learn how to build a chimney, there are several things you need to take into consideration before getting started.
Building a masonry chimney doesn’t require a professional, which can save you a lot of money, but knowing how a chimney works and the importance of building it correctly, can save you from experiencing a dangerous and potentially deadly house fire.
Before building any chimney you should check your local building code requirements to make sure you adhere to your local rules and regulations.
After all, these rules and regulations are put in place for a reason......your safety.
Also, keep in mind that everyone wants to save money.
If you don't feel comfortable with the project, sometimes it pays to just hire a professional who builds chimneys for a living.
However, if you have some masonry experience and you're confident with do-it-yourself type projects, building a chimney yourself is not only rewarding, it's a lot cheaper.
For starters, visit the National Fire Protection Association to view many local codes and regulations.
Before you learn how to build a chimney, you should first understand how a chimney works.
Chimneys have two main functions.
First, they create a draft which pulls in the required oxygen for creating combustion.
Second, they release the combustion products outside the home’s living area keeping the air inside your home clean and safe to breathe.
The draft is created when warm air (or smoke) naturally rises up through the chimney.
Generally speaking taller chimneys create more draft than shorter ones.
Outdoor air currents can sometimes affect draft if they have to blow around obstructions such as areas of the roof or nearby trees.
These obstructions cause the air to blow down the chimney instead of across its outlet.
These air currents affecting draft are called eddy currents.
Therefore, chimney height needs to be a minimum of 3 feet above flat roofs and at least 2 feet above the roof ridge or any raised portion of the roof within 10 feet.
At times, it may be impossible to get enough vertical clearance to prevent eddy currents from affecting the draft.
This is when a chimney cap or chimney hood is installed to minimize the effect eddies have on the draft.
The use of caps and hoods on the chimney also help in the prevention of rain entering into the chimney when it’s not being used.
When learning how to build a chimney, you should first understand the purpose of a chimney flue.
A chimney flue is the opening where smoke passes.
Flues for masonry chimneys are typically rectangular or square, whereas metal chimneys are usually round.
Multiple flues can be used to discharge byproducts if meeting certain conditions:
Chimneys made out of masonry are generally the heaviest part of the house and are made out of noncombustible materials such as brick, stones or concrete blocks.
Therefore, footings require enough strength to hold the chimney’s weight without settling and they need to be placed on well-compacted soil.
Before you jump up and start building the chimney, make sure you have all your basic supplies on hand so you don’t have to stop in the middle of the project and run to the store.
Masonry Chimney Supplies:
Tip: If you are building the chimney to vent a fireplace, use the same or similar type of brick that matches the fireplace’s hearth.
When building the chimney you should always work from the ground upward, which usually means you will start the project on top of the fireplace, if the chimney’s purpose is venting a fireplace.
Make sure you are building the chimney on a reinforced concrete pad.
If not, you will have to lay a pad of concrete 8 to 12 inches thick before you build the chimney, depending on how many stories the house has.
Learning how to build a chimney is a task many homeowners can accomplish on their own.
However, if you have any concerns or you're not comfortable working with masonry equipment, error on the side of caution and hire a professional.