Do It Yourself and Other Educational Chimney and Fire Safety Articles

A poorly drafting fireplace is caused by improper air pressure in your chimney which draws air down instead of up the chimney and out.  As a result, when you start a fire, the smoke enters the room and makes a mess.  A drafting issue is usually caused by one of these problems: your chimney flue is poorly insulated (cold hearth syndrome), the chimney flue is too large for the opening, the chimney is too short, an obstruction in the chimney is interfering with drafting, you are missing a chimney cap, prevailing wind is overpowering the chimney’s natural draft, or maybe you simply forgot to open the damper or it is only partially opened.

The quickest solution and first thing you should check if you have smoke entering your house when you light a fire is if your damper is shut or only partially opened.  Sometimes, people shut the damper to retain heat in the room and forget to reopen it when starting a new fire.  If the damper assemblies are covered in creosote or corroded, then the door may not open far enough to allow smoke to exit in which case, the damper will need to be replaced.

If you have a drafting issue you can consider getting a top sealing damper that can be mounted at the top of the chimney. The top sealing damper opens and closes creating an air-tight seal, unlike a traditional chimney cap which does not close.  A lot of times, people want to know the difference between the top sealing damper and the chimney cap.  While they both keep critters and rain out, the extra benefit of the top sealing damper is that you can close it to retain heat and therefore, save money!

If your flue is too large for the fireplace opening, then you may have smoke absorbed into your house. The surface area of the fireplace opening must at least be ten times greater than the surface area of the chimney flue opening to handle smoke properly.

If your chimney is too short, you can fix this by adding an extension to the top of your chimney.  Your chimney should be at least ten to twelve feet tall to allow for proper drafting, especially if your chimney is located on the exterior of your house where cold air can keep the interior temperature of your chimney colder.  A natural draft requires the hot air to rise and works better in a well-insulated chimney flue.  This is known as cold hearth syndrome, when the cold condensed air inside the chimney prevents the hot air and smoke from the fire to rise.  If you have cold hearth syndrome, you need to find a way to isolate the cold outside air from the chimney airflow and the top sealing damper mentioned earlier is a great solution.

A tight-fitting fire screen can also work to prevent the vacuum effect causing smoke to direct back into the house.  Another piece of equipment we recommend is a smoke guard, which you can read more about in our DIY equipment section.

Because there are many reasons and solutions behind a drafting problem, it is best to start out with those solutions that are simpler such as checking the damper, fire screen, or inserting a smoke guard or chimney cap first.  If those are still unsuccessful, then consider construction such as extending your flue with the help of a professional chimney sweep.