For Those of You That Have Built a Masonry Chimney ..

Carbon12 wrote:Not sure what you plan to burn but have you considered a metal chimney?

Ouch! OK, I deserved that! Yes, masonry chimney best, however, cutting through concrete floor and excavating beneath? Sounds,......unpleasant. Was just throwing out an option.

I'm in the process of doing a block chimney inside my shop. I went down 48", and poured a 3-1/2' x 4' footer, 12" thick. Figured it would be supporting around 4800 pounds. I now have a solid base, below frost. I'll never need to be concerned about things moving around. That being said; My floor is still dirt. I surly wouldn't want to undermine a nice new concrete floor. Frost would be my only concern also. If I were you, and had concern, you could buy one of them round cardboard tubes. Dig a hole strait down. Drop the tube in the hole, and fill with concrete.

waldo lemieux wrote: we guarantee all our erections

I always guarantee my erections too.

Crap, I wish I could still guarantee MY erections--anymore it's kind of a crap shoot--

Check your aim,......

freetown fred wrote:Crap, I wish I could still guarantee MY erections--anymore it's kind of a crap shoot--

So is that while yer sitting or standing?

Oh sure, laugh it up now you younger woodpeckers!

Well Stecks,whaddya go with ?

I read this earlier today didn't comment while I gave my brain a minute to comment. Nope, not about you old farts erection problems....I'm talking about the chimney/floor.

I put my chimney up 4 or 5 years ago. It's inside, on a floating slab. Now it's a heavy slab, 10-12" footings around the perimeter and about 5-6" in the rest. All of this sits on a hundred yards of shale, compacted over sand. Water table is usually around 5' down.

The OP is in the same spot I was except my slab may be a little more sturdy just because the concrete guy was my brother-in-law.
What I mean is my slab was done long before I thought about a chimney or made provisions for it.

Having said that I'd risk throwing a chimney up on the existing floor before chipping out the floor, digging much deeper to put a deeper base in and here's why. A slab is meant to float, and usually float it will. I would think if you make a chimney "hold still" while the floor around it moves, something is gonna go awry.

See my signature for the legal disclaimer

cabinover wrote:I read this earlier today didn't comment while I gave my brain a minute to comment. Nope, not about you old farts erection problems....I'm talking about the chimney/floor.

I put my chimney up 4 or 5 years ago. It's inside, on a floating slab. Now it's a heavy slab, 10-12" footings around the perimeter and about 5-6" in the rest. All of this sits on a hundred yards of shale, compacted over sand. Water table is usually around 5' down.

The OP is in the same spot I was except my slab may be a little more sturdy just because the concrete guy was my brother-in-law.
What I mean is my slab was done long before I thought about a chimney or made provisions for it.

Having said that I'd risk throwing a chimney up on the existing floor before chipping out the floor, digging much deeper to put a deeper base in and here's why. A slab is meant to float, and usually float it will. I would think if you make a chimney "hold still" while the floor around it moves, something is gonna go awry.

See my signature for the legal disclaimer

Yes, what I'm doing is bending aluminum trim coil around my chimney BEFORE pouring the floor. This way no chance of the two bonding together. I know a guy who dug 42" deep holes for pole style car port. Then poured the holes, and slab all in one pour. I told him that wouldn't work, and he'd have problems. His footer holes, and slab needed to be separated. Too late though. It was already done. WOW!, Come the following spring, it looked like bomb was dropped on his slab. The whole slab was busted apart. Heaved & cracked all over the place. It looked more like a 10 wheeler just dumped a load of demolition concrete. Then pushed it around with a dozer. It was way worse than I imagined it would be. He had to start over.

30 years ago I dug holes around the perimeter for a two story building, filled the holes with concrete level with the
ground. Then I formed for a 8" continuous lintel on top of the holes. I put 3/4" foam on the bottom where there was dirt, not on the concrete poured holes.
Poured the lintel, layed 6" block on the lintel then built the two story building on top. People said it would crack, the building would blow over.
Well still not a crack and it's still standing.
The end of the house has a walkout basement, the footer for the 24' chimney is 1 foot deep (top level with the ground) and about 2 foot square,
not a crack.

LoschStoker wrote:30 years ago I dug holes around the perimeter for a two story building, filled the holes with concrete level with the
ground. Then I formed for a 8" continuous lintel on top of the holes. I put 3/4" foam on the bottom where there was dirt, not on the concrete poured holes.
Poured the lintel, layed 6" block on the lintel then built the two story building on top. People said it would crack, the building would blow over.
Well still not a crack and it's still standing.
The end of the house has a walkout basement, the footer for the 24' chimney is 1 foot deep (top level with the ground) and about 2 foot square,
not a crack.

You poured holes, and lintels at two different times, not together. I shouldn't have any problems with my future concrete floor bonding to the chimney. For the cost of a piece of aluminum, tar, etc. (anything to separate the two), I'm not going to take any chances. You also used 3/4" foam between hard concrete, and hard ground. An ex-neighbor did the same thing. Never any cracks in his floor. The problem with cutting corners is; although you may have had good results, too many others haven't.

lots of good info here .. this thread came alive With the temps dropping, this year I have put together some SS double wall pipe sourced off of craigslist to get things started (hopefully). I can always sell the stuff and go masonry later. By the time I get to it, temps will be too cold for mortar. Currently I am still working on the building interior .. insulation and ceiling are my tasks now. This one man show only moves so fast. My guess is that I wasted money on the SS as it will never be done this winter .. probably should have waited till spring and worked on the masonry. You are on your own with the erection problems.

bsteckel wrote:lots of good info here .. this thread came alive With the temps dropping, this year I have put together some SS double wall pipe sourced off of craigslist to get things started (hopefully). I can always sell the stuff and go masonry later. By the time I get to it, temps will be too cold for mortar. Currently I am still working on the building interior .. insulation and ceiling are my tasks now. This one man show only moves so fast. My guess is that I wasted money on the SS as it will never be done this winter .. probably should have waited till spring and worked on the masonry. You are on your own with the erection problems.

Hi bsteckel, I know a masonry chimney is best. That's why I'm putting one in the shop. The house has a metal chimney up through the inside. It's been there about 12 - 13 years now. I rinse it down every spring with baking soda & water. When the time comes, I'll replace it with another metal chimney . Reason is; In my case, the metal chimney goes from the basement, clean up through, and out the roof. I never had to touch ANY framing lumber. I have exactly 2" clearance all around the metal chimney, as if it was planned that way. A concrete chimney would involve lots of framing, and bull work in tight quarters (Notice I like interior chimneys). I got to thinking recently, when the time comes to replace the metal chimney, all I really need to replace is the one top section. The rest of the chimney is like new. All chimneys condensate down about 12 inches from the top. That's where my metal chimney is going to fail. Moisture & fly-ash has it rusted at the top. Oliver