The measurements of a chimney are a minimum of four inches bigger in all directions than the flue.
Building a chimney.
For a masonry chimney this usually means that you will be building your chimney right off the top of a fireplace if the chimney is designed to vent a fireplace using a brick that is similar to that used to build the hearth.
If you want to learn how to build a chimney there are several things you need to take into consideration before getting started.
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.
Wood kindling and other materials that may travel up the chimney must be at a minimum of two inches away from the outer part of the chimney.
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.
Fire blocking perhaps 3 4 thick plywood or osb fire rated is intended to slow or even prevent the movement of a chimney chase fire between building floors and to prevent the increase of fire intensity and spread by the chimney effects that would occur inside the chimney chase without fires topping.
Outside chimneys can be only one inch from the outer wall of the home.
Build the smoke chamber.
You will need to start building your chimney from the ground up.
Many locales require permits before a chimney can be built and demand meticulous inspections during the construction to make sure that the chimney conforms to area building codes.