How to Build a Fireplace Chimney

Adding a fireplace to your home can help you reduce heating costs. Fireplaces, like other heating appliances, need chimneys so the smoke from the burning wood leaves your house. It's best to hire a professional to do the job for you, but if you're determined to build your own chimney, here are some basic things to consider:

  • Calculate the flue dimensions and minimum height The sizes needed for your flue and the height of your chimney are relative to the open area of your fireplace. Review your fireplace manual or check with the Brick Industry Association for dimension charts and formulas [source: BIA].
  • Support the masonry Chimneys are incredibly heavy, often the heaviest part of a house. They need to be constructed on an 8- to 12-inch (20- to 30.5-centimeter) concrete footing at or below the foundation of the house and should extend at least 6 inches (15 centimeters) in all directions around the edges of the chimney [source: Phillips].
  • Keep away from combustible materials Masonry chimneys must be at least 2 inches (5 centimeters) away from combustible materials on all sides [source: Phillips].
  • Chimney lining You should line your chimney with vitrified fire clay tile, to withstand rapid temperature fluctuations [source: Phillips].
  • Chimney wall thickness Chimneys must have walls at least 4 inches (10 centimeters) thick, not including the flue. Exterior chimneys need walls 8 inches (20 centimeters) thick to withstand weather elements [source: Phillips].
  • Chimney top clearance The chimney should extend 2 feet (60 centimeters) above anything within 10 feet (3 meters) horizontally of its peak. Cap the chimney to keep birds and other animals out [source: Walker].