Fireplace construction help

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New Member
Dec 5, 2005
When lying on my back, and looking up into the fireplace (Damper closed), at the section where the throat of the chimney meets the brick facade inside the room ( I think its called the Lintel) there is no mortar along the whole length of the lintel area. I do feel cold air coming down, but my question is, should this area be closed up with mortar, or should it be mortar-less. I am hoping this is the answer to my smoke problem.
Any information would greatly be appreciated.

Thanks in advance


Minister of Fire
Nov 19, 2005
Poughkeepsie, NY
If that crack is the answer to your smoke problem, then you have a much bigger problem inside the chimney. I think you should have the chimney inspected for cracks. I'd bet Elk might agree here.


Were the original masons named Moe Larry and Curly. Lucky you started posting here. Where do you live?
Do not use that fireplace till it is repaired Fire bug is correct strips of fiber glass will work to prevent drafts.
I still say one should also cement the crack. If the original we talked about is over !" do this examine the area again
What I am thinking stuff the area with fiberglass insulation then cut some 1/2" slate 2" wide strips and push then up into place using the stuffed fiberglass as friction downward Maybe 3" wide Then mortar the crap out of the area You could use Hydraulic cement it sticks better and dries fast ,Brand name Drylock, comes in paint can like containers. If you have another crack or void like crack as you found and cold air is streaming down got to seal that as well.

Think yours is bad? Right after you’re past post and my reply. I was doing a final inspection, on a new home, looked up into the fire box what a mess. No solid fill behind the firebrick I could look up same situation as yours and see the wood header. Got so pissed I am Making them remove the entire firebrick and rebuild the firebox. Paying for 3 additional inspections as I witness what they are doing. As the first time they were clueless.. Come to find out when I asked to speak to the mason, ( I used mason term only for identification not in reverence to a skill). He does not speak any English and I do not speak Brazilian. I find out he been in the country 2 months, so much for being a licensed mason. Now I am wondering what else could be wrong with the chimney. I can’t pass it, as was not done by a licensed mason. Yes I did a throat inspection there. Nobody was at the job. I did not know the mason was not licensed. The throat was ok but the firebox had not been built yet nor the damper set or the brick facing. I cannot watch every chimney 8 hours a day to make sure all is well, while it is constructed. Oh! Btw the house is scheduled to pass Thursday. Here what is going to happen?

#1 Hire a licensed Mechanical Engineer to inspect the chimney and certify it adheres to code. Then submit a mechanical permit for the chimney listing a licensed mason to sign and take responsibility for the work
#2 Take it down and hire a licensed mason to re-construct it

#3 Take it down, power vent the oil burner and box and roof the existing jog where the former chimney was.

This is what is known as a burner. At some point it will cause a fire in it current condition. Even the flue liner had huge chunks of mortar
Protruding out between the flues. Called Snots. Great to catch and enhance creosote build up.


Seasoned Moderator
Nov 17, 2005
Western Mass.
elkimmeg said:
Were the original masons named Moe Larry and Curly.
This is what is known as a burner. At some point it will cause a fire in it current condition.
The problem here is that real masonry is becoming a lost art because a couple generations went by without people using their fireplaces heavily. So now, any Moe, Larry or Curly thinks as long as you have 1" of masonry you aren't gonna catch the wood behind it on fire.

The masonry industry (different than our "hearth" industry" desperately needs education and being more important because as Elk mentioned, no inspector can watch every move.


Craig I could not agree more. For the most part the regular masons are decent in my town. Every now and then I climb the pipe staging to look down to see what is going on. Most invite me up. The regulars are glad I'm around even point out things they see
on other jobs not up to code. Nobody like to loose a contract or bid to a guy that under cuts them and then cuts corners. They all know I use the angle mirror to examine all around the firebox and behind it. I call it leveling the playing field. They applaud when I make others tear them down because they were not built right. By making a poorly constructed one torn down sends a clear message to others I will not tollerate burners


Staff member
Ok, I'll open the can of worms. If masonary chimneys are so dangerous and prone to poor construction (not to mention costing a fortune) why aren't they just outright outlawed in new construction?

They are obviously only good for "mood fires". Their most popular use for two decades has been for wood burning inserts. I seriously doubt that any code addresses the fact that a fireplace is going to have an extra six or seven hundred pounds of weight added to it. I have always had the unpleasant thought that some day or night a 1000 degee burning mass of wood and steel was going to plument into my basement.


Good question: Most hearth pads are formed and poured sloping which shifts the weight to the supporting members and the foundation creating a wedge effect. Most foundations are 10" so part of the hearth pad in poured over the supporting foundation.
In my area the masons drill re-rod into the wood headers and support them with the foundation then add a criss cross in the middle. Support comes from the foundation on the back and 2' on each side wedged by the slope and re-rodded that should work.
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