Jack Pixley's Homeowner's Guide

To have a chimney fire can be scary, but it is nothing in comparison to a structural fire in one’s home. Unfortunately, some existing fireplaces do not conform to current building codes. For this reason, we recommend people use their fireplace for fun only. Do not try to turn it into a furnace unless you know for certain that it meets the fire and building codes. The National Bureau of Standards provided some valuable fire safety information in 1980. They built a masonry fireplace to minimal building code requirements and then conducted heat transfer tests. They found that if one left the glass doors open and closed the screen, a great amount of room air would enter the fireplace opening and go up through the flue. This would result in a much lower flue gas temperature and therefore reduce the heat transfer through the chimney walls and to the surrounding combustibles. They also recommended limiting the length of fire to five hours.

Our CSIA-certified technicians can advise you of methods to help avoid heat transfer from your chimney components to the surrounding combustible walls. For example, we can rebuild the back wall of the firebox and add an insulating concrete material called “Thermix.” The smoke chamber can also be made much safer by applying a 1 ½” thickness of “Chamber Tech 2000.”

Please note: It is difficult to know if an existing fireplace is safe. In order to determine if a fireplace/chimney meets code, one would need to do a level 3 inspection as outlined in the National Fire Protection Association (NFPA) Standard 211. This would require one open up the wood structural walls surrounding the chimney to check for proper clearance to combustibles. In addition, holes would need to be made in the chimney walls to check for the type and thickness of materials used during construction.