What can we do to stir up controversy? Since a lot has been discussed about safety lets start there. This post will need poster participation. So you are planning to install an insert in your firebox. Has it ever occurred to you the 90% of most fireboxes do not pass code. I know, I know, here he goes again, Mine is 3 years old and passed inspections when I bought the home.
If one reads their installation manual, there will be code language requiring the fireplace and firebox to be code compliant, before the insert is installed. Additionally code requires a complete inspection report of your current firebox, chimney, and the liners. Plus cleaning if necessary.
So why do I claim 90% are not code compliant. Well behind the firebox 12” of solid masonry is required. That requirement is reduced, by allowing two courses of bricks and facing the firebox with fire clay bricks. The space behind the regular bricks and the facing firebrick is supposed to be solid filled with masonry. It seems that when most masons start the curvature of the fire box, they get lazy and fail to fill that void with cement or mortar. Remember what is required solid masonry, not leaving a void. Someone will say the air space itself is a form of insulation, They would be right but that applies to dead air space this is open. So what are the dangers? Without the solid backing the bricks over time and heat exposure crack mortar falls out and the top rows can actually fall out. The other concern is that cavity becomes a reservoir, where creosote fall into. I have seen animal nest, leaves, and sometimes left over 2/4 construction block left in there.
So how do you know if this condition exists in your current chimney? I use a simple tapping test. Either using my knuckles or a block of wood I tap the firebricks starting at the bottom you hear that solid sound. As you move up the firebricks to the top that solid sound should be consistent. If the sound changes to a more hollow sound guess what you just discovered the exact situation I outlined.. At that part of my final inspection out comes my telescoping dental type mirror with a flashlight. That is how I discovered all the unusual debris found in there. The inspection is over that new chimney fails. It’s pain in the A** to get mortar in their afterwards but it can be done. Most masons have learned not to short change this, as they know I check it .
In our state MA, we are required to attend x amount of training seminars to stay certified, called contact hours. Some of these seminars are videos examining causes of fires and actual filming or what transpires during fires. Some are a combination of what went wrong or what could go wrong. Out of these seminars, one learns a few things about containment and how to spot a situation before there is a fire. Containment. did you know you are safer to night with your bedroom door closed? That is part of the reasoning for smoke detectors located in your bedrooms. I cringe at the suggestions of cutting vents in your floors, knowing the floors and ceilings act as natural containment barriers. It buys time for
safe exit
Back to the original post subject. How dangerous is this void collection area? Inserts with approved full-length liners are safest. No way of rusting out and blowing hot sparks into the creosote reservoir. Direct connects situations the risks are elevated. One when cleaning the clay flues above, the creosote falls into this void, adding more fuel the combust later. When one thinks about it, most fire places are used only a few times a year and for short durations. This situation changes when one adds the insert now they are burned 24/7. They produce more creosote than the original few burns in the fireplace. Plus all that constant heat.
The reservoir may never ignite but these situations can be corrected. One, while normal cleaning shop vac out the accumulations there. Two, fill it in with mortar to prevent any future concerns.
There are ways to prevent chimney fires one hot initial burn helps using seasoned wood helps constant inspections helps and after inspections if you see cause for cleaning then clean it out. Today is near the mid point of the burning season It’s warm out and the roof has no ice and snow. Time for my mid winter cleaning. In 25plus years never a chimney fire burning 2 stoves. Luck has nothing to do with it. Knowing your current conditions and preventive measures is not luck. I guess what I want to know is how many actually hear that hollow sound near the top of the fire box. When tapping the firebricks Don’t want to actually get in there use a broom stick and tap? Maybe Mo heat can start a poll I would love to hear the feedback. Craig has voiced his concerns questioning masonry fire places
If one reads their installation manual, there will be code language requiring the fireplace and firebox to be code compliant, before the insert is installed. Additionally code requires a complete inspection report of your current firebox, chimney, and the liners. Plus cleaning if necessary.
So why do I claim 90% are not code compliant. Well behind the firebox 12” of solid masonry is required. That requirement is reduced, by allowing two courses of bricks and facing the firebox with fire clay bricks. The space behind the regular bricks and the facing firebrick is supposed to be solid filled with masonry. It seems that when most masons start the curvature of the fire box, they get lazy and fail to fill that void with cement or mortar. Remember what is required solid masonry, not leaving a void. Someone will say the air space itself is a form of insulation, They would be right but that applies to dead air space this is open. So what are the dangers? Without the solid backing the bricks over time and heat exposure crack mortar falls out and the top rows can actually fall out. The other concern is that cavity becomes a reservoir, where creosote fall into. I have seen animal nest, leaves, and sometimes left over 2/4 construction block left in there.
So how do you know if this condition exists in your current chimney? I use a simple tapping test. Either using my knuckles or a block of wood I tap the firebricks starting at the bottom you hear that solid sound. As you move up the firebricks to the top that solid sound should be consistent. If the sound changes to a more hollow sound guess what you just discovered the exact situation I outlined.. At that part of my final inspection out comes my telescoping dental type mirror with a flashlight. That is how I discovered all the unusual debris found in there. The inspection is over that new chimney fails. It’s pain in the A** to get mortar in their afterwards but it can be done. Most masons have learned not to short change this, as they know I check it .
In our state MA, we are required to attend x amount of training seminars to stay certified, called contact hours. Some of these seminars are videos examining causes of fires and actual filming or what transpires during fires. Some are a combination of what went wrong or what could go wrong. Out of these seminars, one learns a few things about containment and how to spot a situation before there is a fire. Containment. did you know you are safer to night with your bedroom door closed? That is part of the reasoning for smoke detectors located in your bedrooms. I cringe at the suggestions of cutting vents in your floors, knowing the floors and ceilings act as natural containment barriers. It buys time for
safe exit
Back to the original post subject. How dangerous is this void collection area? Inserts with approved full-length liners are safest. No way of rusting out and blowing hot sparks into the creosote reservoir. Direct connects situations the risks are elevated. One when cleaning the clay flues above, the creosote falls into this void, adding more fuel the combust later. When one thinks about it, most fire places are used only a few times a year and for short durations. This situation changes when one adds the insert now they are burned 24/7. They produce more creosote than the original few burns in the fireplace. Plus all that constant heat.
The reservoir may never ignite but these situations can be corrected. One, while normal cleaning shop vac out the accumulations there. Two, fill it in with mortar to prevent any future concerns.
There are ways to prevent chimney fires one hot initial burn helps using seasoned wood helps constant inspections helps and after inspections if you see cause for cleaning then clean it out. Today is near the mid point of the burning season It’s warm out and the roof has no ice and snow. Time for my mid winter cleaning. In 25plus years never a chimney fire burning 2 stoves. Luck has nothing to do with it. Knowing your current conditions and preventive measures is not luck. I guess what I want to know is how many actually hear that hollow sound near the top of the fire box. When tapping the firebricks Don’t want to actually get in there use a broom stick and tap? Maybe Mo heat can start a poll I would love to hear the feedback. Craig has voiced his concerns questioning masonry fire places
